Dubai Building Code (2021)

Dubai Building Code

Part F: Structure

F 29

F.6.5

Structural steel

F.6.5.1

Design basis

The design of structural steel shall be in accordance with AISC 360 including codes

and standards referenced therein. Seismic design shall follow AISC 341.

Compatible materials shall be specified in accordance with standards set by the

ASTM International (ASTM). Welding shall be specified in accordance with standards

set by the American Welding Society (AWS).

F.6.5.2

Steel grades

Table F.5 and Table F.6 summarize the steel grade that shall be adopted in the

design. Steel sections can be selected in accordance with either American or British

specifications. The Engineer is responsible for ensuring compatibility of the material

specification with the design basis, including detailing requirements and ductility in

general.

In particular, the following requirements shall be included during the design of the

permanent and temporary conditions.
a) Connections shall have adequate strength to transfer the forces to which they are

subjected during their lifetime.

b) The stresses across connections caused by restraint of creep, shrinkage and

temperature change (volume change) shall be included in the design.

Connections shall meet the durability and fire resistance requirements of the

connecting elements.

d) Connections shall be checked for all load scenarios including horizontal forces

arising from earthquake and wind events.

e) Precast members shall have positive connections (ties) to the supporting

structures unless seating lengths are greater than maximum expected

movements.

F.6.4.7

Precast staircase

Precast staircases may be included in buildings if they are not part of the lateral load

resisting structural frame.
The design of precast stairs shall be in accordance with ACI 318-19 and the

PCI handbook

[Ref. F.12]

. They shall be designed in such a way that they can be

safely incorporated into the structure. Additional design recommendations are

provided in F.12.

Dubai Building Code

Part F: Structure

F 30

Table F.5 Steel grades based on American specifications

Type of section

Material specification

N/mm

Wide flange

ASTM A992M

345

Channels

ASTM A36M

250

Angles

ASTM A36M

250

Plates

ASTM A36M

250

Built-up sections

ASTM A36M

345

Hollow structural section (HSS)

rectangular or square

ASTM A500
Grade B

240

HSS round

ASTM A500
Grade B

240

Pipe

ASTM A501

240

Pipe (alternate)

ASTM A53M, Grade B
Type E or S

240

Anchor rods

ASTM F1554

380, with supplemental

requirement for weldability f

= 517

Headed shear stud

AWS D1.1, Type B

345

Table F.6 Steel grades based on British specifications

Type of section

Material specification

N/mm

Beam

BS EN 10025-1 Grade 355J0 or
Grade 275J0

295 to 355 (based on thickness)
225 to 275 (based on thickness)

Universal column

BS EN 10025-1 Grade 355J0 or
Grade 275J0

295 to 355 (based on thickness)
225 to 275 (based on thickness)

Angles

BS EB 10056-2
Grade S275

275

Bars and plates

BS EN 10025-1 Grade S275 or
Grade S355

295 to 355 (based on thickness)
225 to 275 (based on thickness)

Hot-finished square, rectangular

and circular hollow sections

(SHS, RHS and CHS)

BS EN 10210 Grade S355J2H

240

Cold-formed SHS, RHS and

CHS

BS EN 10219 Grade S355J2H

240

In addition to the steel grades listed above, high strength steel grades with minimum

yield strength of 460 N/mm

can be adopted in accordance with the requirements of

BS EN 10025-4:2019.

F.6.5.3

Plate thickness

Steel plate for built-up sections shall have a minimum thickness of 6 mm.

Dubai Building Code

Part F: Structure

F 31

F.6.5.4

Structural connections

F.6.5.4.1 Bolted connections

Bolted connections shall be designed and constructed

in accordance with AISC manual of steel construction

[Ref. F.15]

including AISC specification for structural

joints using ASTM A325 or A490 bolts

[Ref. F.16]

For higher strength applications (> 60,000 psi),

ASTM A307 shall be followed.

F.6.5.4.2 Welded connections

Welding design and procedures shall be in accordance

with AWS D1.1 or BS EN ISO 15614.
Welding should not be undertaken on-site. If

unavoidable, the detailed method of work with the

necessary certificates and tests shall be submitted

for approval. In addition, welding procedures shall be

implemented by accredited welders in accordance with

relevant AWS requirements.
Connections shall not be detailed to rely on the

combined strength of welding and bolting at the same

time under any circumstances.

F.6.5.4.3 Post-installed anchors

Post-installed anchors into reinforced concrete

elements may be used for the purpose of supporting

steelwork where it is impractical to install cast-in

anchors.
Post-installed anchors shall be designed based on the

provisions of ACI 318-19, with consideration for all

conceivable failure mechanisms (see Figure F.14).

Figure F.14 Failure modes for anchors (© ACI. Modified figure based on Figure R17.5.1.2, ACI 318-19, pg. 238)

Key

01: Steel failure

02: Pullout

03: Concrete breakout

04: Concrete splitting

05: Side-face blowout

06: Bond failure – Single

07: Bond failure – Group

08: Steel failure preceded by concrete spall

09: Concrete pryout for anchors far from a free edge

10: Concrete breakout

(a) Tensile loading

(b) Shear loading

Dubai Building Code

Part F: Structure

F 32

F.6.6

Masonry

F.6.6.1

Design basis

The design of load-bearing masonry walls shall be in accordance with TMS 402/602

including codes and standards referenced therein.
The design of non-load-bearing masonry walls which are not part of the main

structural frame, shall be in accordance with either TMS 402/602 or BS EN 1996-1,

BS EN 1996-2 and BS EN 1996-3.

F.6.6.2

Wall panels

Wall panels shall be constructed with suitable strength bricks or concrete blocks,

arranged in an interconnected manner, typically using cement mortar.
Wall panel dimensions between movement joints and/or lateral supporting structures

shall not exceed the capacity of the wall panel. Wall panels shall be tied to all vertical

and horizontal supporting structures. Supporting structures shall have sufficient

strength and stiffness to provide the support required by the wall panel without

incurring movement that would cause distress.
Any cuts/chases into wall panels shall be included in the calculations by the Engineer.

F.6.6.3

Brick and block strengths

Solid bricks and blocks for load-bearing wall panels shall have a compressive strength

of not less than 9 N/mm

. Bricks and blocks (including hollow blocks) in non-load

bearing walls shall have a compressive strength of not less than 6 N/mm

Dubai Building Code

Part F: Structure

F 33

F.7.1

General

Loads shall be defined in accordance with ASCE/SEI 7-16 and this section.

F.7.2

Load combinations

Loads shall be factored and combined in accordance with Ch. 2 of ASCE/SEI 7-16.

The results from compatible linear analyses of load cases acting individually may be

combined and summed algebraically.

F.7.3

Dead loads

Dead loads shall be calculated using the densities and volumes of the materials

making up the construction. Default densities of common materials are scheduled in

Table F.7.

NOTE: More refined densities and the densities of other materials can be sourced

from the referenced codes and standards, material data sheets, or obtained via

testing. The Engineer is responsible for ensuring the densities assumed in design

align with those of the specified construction materials.

F.7

Loads

Table F.7

Default material densities

Description

Load (kN/m

)

Concrete (normal weight, including allowance for reinforcement)

Concrete (lightweight, including allowance for reinforcement)

Concrete blockwork (normal weight)

Concrete blockwork (autoclave aerated block)

Steel

Screed and blinding

Float glass

F.7.4

Superimposed dead loads

The Engineer is responsible for determining the superimposed dead loads for

components not included as either live or dead loads (including the anticipated

internal partitions, floor and ceiling finishes, facades and external cladding). Loads

shall be defined as concentrated point loads, uniform loads on plan, and/or uniform

loads on elevation, as appropriate.

The following minimum load allowances (defined as average uniform loads on plan)

shall be adopted for the purpose of evaluating the maximum load effect:
a) internal drywall partitions: 0.75 kN/m

;

suspended services with ceiling finishes: 0.50 kN/m

; and

suspended services without ceiling finishes: 0.30 kN/m

When minimum load effect is critical (e.g. buoyancy check), an appropriate minimum

load criterion shall be assumed. The minimum load for features that are easy or likely

to be removed should be zero (0.0 kN/m

The Engineer shall provide detailed calculations supporting the superimposed dead

load assumptions. If supporting calculations are not provided, the vertical load listed

in Table F.8 shall be included for the partition assumptions.

Where appropriate, dead loads shall make provision for additional weight

concentrated at structural connections.

Table F.8

Minimum superimposed dead load

Type of wall

Superimposed dead load applied vertically, including finishes (kN/m

)

Lightweight block wall

4.5

Normal weight block wall

5.5

Drywall

4.0

Loading plan drawings showing the load provision should be submitted for approval.

The design assumptions shall be validated against the systems installed. Any late

amendments and/or retrospective changes shall not be made without new approval.

Dubai Building Code

Part F: Structure

F 34

F.7.5

Live loads

Minimum uniform live loads shall not be less than those listed in Ch. 4

of ASCE/SEI 7-16. The following requirements shall also be applied.
a)

Concentrated live load shall be evaluated for objects creating significant point

loads, including machinery, vehicles and storage racks.

b) The minimum live load for garage and car parking is 3.5 kN/m

which should

be validated based on the type of vehicles accessing the facility. The Engineer

shall also take into account the load imposed by emergency vehicles along the

designated route.

The live load for drained areas of floor surrounding a swimming pool is 2 kN/m

Pool tanks and other areas susceptible to flooding are to be designed for a load

not less than the maximum retained head of water.

d) The Engineer shall design the supporting structure to withstand the loading

imposed by the mechanical, electrical and plumbing (MEP) equipment in the

designated areas and along the proposed equipment access route.

F.7.6

Soil loads and hydrostatic pressure

Minimum soil and hydrostatic pressure loads shall not be less than those listed in

Table F.9. Lower values shall not be used without project-specific justification.

Table F.9

Material densities

Description

Minimum load (kN/m

)

Soil for planters (saturated)

Compacted soil for trafficable areas

Water

Brackish water

10.3

In addition to the geotechnical requirements specified in F.9, the Engineer shall

include the following in the design of permanent structures.
a) All foundation elements and retaining walls shall be designed following the

recommendations given in the geotechnical interpretive report (GIR).

The design water table shall be established in the GIR considering the fluctuation

of the water table level during the design life of the structure. In particular, the

effect of dewatering in the neighbouring areas, the seasonal variation of the water

table, future developments (such as canal, water bodies, landscaping and similar)

and potential impact of climate change shall be included in the definition of the

design groundwater level. The design groundwater level and its fluctuations shall

be stated by the Engineer in the design drawings and agreed with the Authorities.

c) In any case, the minimum water table level shall be assumed as follows.

In proximity to bodies of water: ±0.00 m Dubai Municipality datum (DMD)

plus 1.0 m for seasonal and tidal variations.

2) Away from bodies of water: actual water table level with dewatering taken into

account, as defined in the GIR, plus 1.0 m for seasonal and tidal variations.

For structures below the water table, hydrostatic uplift and lateral pressures

shall be checked in accordance with Section 10 of BS EN 1997-1:2004 and the

associated United Kingdom National Annex (UK NA). Any dewatering system,

whether used for construction or throughout the design life, is temporary unless

the system can be demonstrated to be reliable throughout the design life.

e) Where construction of the project is staged, or in case of construction on an

adjacent plot, any possibility of unbalanced lateral soil load shall be included.

f) Any retaining wall assumed to be subjected to lateral pressure during

construction shall be designed according to possible surcharge and hydrostatic

loading. The lateral soil pressure arising from compacted soil placement shall be

included where this exceeds the at rest or passive pressure (as relevant).

Dubai Building Code

Part F: Structure

F 35

g) Bracing conditions of the retaining structure and construction sequence shall be

carefully captured in the analysis and design.

h) Uplift due to heave shall also be included for both permanent and temporary

conditions whenever applicable.

F.7.7

Construction load

Minimum design load requirements during construction of buildings shall be defined

in accordance with ASCE 37.
Construction-stage loads, including locked in stresses arising from the construction

sequence and affecting the overall behaviour of the structure, shall be included by the

Engineer.
The Engineer shall clearly state the construction load assumptions on the detailed

design drawings and verify that the structural system can withstand these loads

during all stages of construction.
Any departure from the Engineer’s assumptions by the Contractor’s construction

sequence shall be assessed.

F.7.8

Accidental impact load

Structural elements shall be designed to resist accidental impact loading conditions

specified under Section 4.6 of ASCE/SEI 7-16. A secondary protection system should

be provided to all primary structural members to avoid accidental impact load.

F.7.9

Helipad and heliport loads

The minimum live load allowance for helipad and heliports shall be in accordance with

Section 4.11 of ASCE/SEI 7-16.

F.7.10

Self-straining forces

Structures shall be designed to resist any self-straining forces arising from the

contraction or expansion of structural elements.
Such volume changes can result from shrinkage, creep and/or moisture change in

component materials, including the soil. It might occur at any stage in the structure’s

lifecycle.
The use of details to alleviate self-straining forces may be used when practical and

when not in violation of any assumed load paths. Such details, where permanent,

shall be durable and have provision for maintenance.

F.7.11

Thermally induced forces

Thermally induced forces shall be derived considering the structural restraints, and

the changes in temperature of structural members arising across the construction/

operational phases, seasonal and daily variations.

For effects on covered concrete structural members, mean monthly temperatures

should be used to establish an appropriate temperature range. A default thermal

range of ±20 °C may be used for exposed elements above ground level and ±15 °C

for non-exposed elements (i.e. basement). Gradient thermal analysis (non-uniform)

shall be applied for permanently exposed slabs like roofs and exposed last podium

floors.
For steel structural members and structural members exposed to solar radiation,

a range equivalent to the maximum temperature swing is appropriate. A default

thermal range of ±25 °C may be used for protected steel elements. For exposed

steelwork, this can arise from hourly maxima and minima. The Engineer shall assess

the thermal range and assess the thermally induced forces on a case by case basis

considering the construction stages, exposure and when the steel structure is locked

in the final configuration.

Dubai Building Code

Part F: Structure

F 36

NOTE: For further guidance, the mean monthly

temperatures and relative humidity values for specific

sites are available from the National Centre for

Meteorology and Seismology website

(

www.ncms.ae/

)

[Ref. F.4]

. Figure F.15 and Figure F.16

show air temperature data and relative humidity data,

respectively, from the National Centre for Meteorology

and Seismology.

Temper

atur

e (˚C)

Jan

Mar

Apr

Jun

Jul

Sep

Oct

Dec

Humidity (%)

Jan

Mar

Apr

Jun

Jul

Sep

Oct

Dec

Dubai Building Code

Part F: Structure

F 37

F.7.12

Design for wind loading effects

F.7.12.1

Design basis

The Engineer shall calculate the effects of wind loading on buildings. The calculation

shall take into account strength for life safety, and serviceability for buildings

movements affecting cladding or building occupant comfort. Calculations for wind

design shall be based on ASCE/SEI 7-16. The Engineer shall also use supporting

information and additional rules for application in Dubai from the DBC.

NOTE: The rules are intended to fully cover buildings of the kind envisaged in the

writing of a code of practice. For unusual constructions, additional studies are

expected, such as wind tunnel testing, and might result in a need for an appropriate

variation of the rules.

F.7.12.2

Wind pressures

This clause provides the basis for calculation of wind pressures to be used with

ASCE/SEI 7-16. The wind speeds of Table F.10 shall be used instead of the wind

maps in Section 26.5 of ASCE/SEI 7 16.

The 50 MRI wind speed stated in Table F.10 shall only be used in accordance with

Clause 5.3.5 of ACI 318-19.

Table F.10 Reference wind speeds per risk category as defined in Clause 1.5 of ASCE/SEI 7-16 and mean

recurrence interval (MRI) as defined in the RWDI report

[Ref. F.5]

ASCE/SEI

7-16 MRI

(years)

Reference wind speed

for 3 s gust at

10 m height on open

terrain, V = V

ref

(m/s)

Application

Serviceability – occupancy comfort (refer to F.7.12.4.2)

Serviceability – displacement (refer to F.7.12.4.1)

Strength in accordance with Clause 5.3.5 of ACI 318 19

300

Strength – category I

700

Strength – category II

1,700

Strength – category III

3,000

Strength – category IV

Where wind tunnel testing is used together with up-crossing or storm-passage

methods to account for directionality, the wind directionality factor (K

) shall be

taken as 1.0.
In all cases, the design wind pressure shall be not less than 1 kN/m

Dubai Building Code

Part F: Structure

F 38

F.7.12.3

Wind tunnel testing

F.7.12.3.1 Requirements for testing

The wind behaviour of buildings meeting any of the following criteria shall be wind

tunnel tested:
a) taller than 120 m;
b)

the height of the building is greater than five times its average width normal to

the wind direction over the top of the building (i.e. an aspect ratio, H/B

> 5);

c) of unusual shape or surroundings not covered by the wind loading provisions of

ASCE/SEI 7-16 or other reliable published data, and which cannot be designed

safely with conservative wind loads; or

d) any other building where the designer wishes to better establish the wind

behaviour.

Wind tunnel testing shall follow the wind tunnel procedure described in Ch. 31 of

ASCE/SEI 7-16.

F.7.12.3.2 Wind direction factors

Wind climate information used for directional evaluation of wind strengths shall be

provided in any wind tunnel reports where these are used.

F.7.12.3.3 Peer review of wind tunnel testing

The Authority might require a peer review for wind tunnel testing of unusual

buildings or where testing provides results which are not readily comparable to

codified values.
Suitable reviewers shall have a recognized engineering qualification and at least

15 years of full-time experience in relevant wind engineering education and practical

application.

F.7.12.4

Allowable building movements for wind

F.7.12.4.1 Allowable displacement

Building overall displacements shall be calculated using 10-year return (MRI) wind

pressures and total building height (H).

Building inter-storey shear shall be calculated using 10-year return (MRI) wind

pressures and floor to floor height (H

These two calculations shall meet the limits given in Table F.11.

Table F.11

Displacement limits

Description

Deflection limit

Overall displacement

H/500

Inter-storey drift

between H

/400 and H

/600

The purpose of the overall displacement calculation is to control displacements of the

building which might cause overstress or fatigue damage or loss of effectiveness to

cladding, internal partitions or other non-structural components of buildings.
Inter-storey displacement may be estimated from inter-storey drift or calculated to

include other deformations of the structure.

Dubai Building Code

Part F: Structure

F 39

F.7.12.4.2 Motions affecting occupant comfort

Accelerations of the uppermost occupied floor shall be assessed for return periods of

1 year and 10 year return with the structural damping described in F.7.12.5.

The motions shall be compared with internationally recognized criteria such as those

of ISO 10137 (see Figure F.17) or as described in ASCE guide wind-induced motion

of tall buildings: designing for habitability

[Ref. F.6]

Motions of a building due to the wind might affect occupants directly or cause

motion of contents such as hanging objects and water, which can also cause concern

to some individuals. Motions should be kept within an appropriate limit, noting

that acceptability of motions is subjective and that other factors, including noises

resulting from building movement, can also trigger concerns.

F.7.12.5

Structural damping for assessment of wind responses

Unless design measures or special construction provide additional damping, the

estimates of structural damping of Table F.12 shall be used to assess motions under

serviceability conditions and for strength design. Values are given for buildings

with main lateral load resisting structure of steel or concrete. For composite steel/

concrete constructions, intermediate values should be used.

0.06

0.1

0.2

0.3

0.5

eler

ation (milli-g)

Natural frequency (Hz)

Oﬃce

Residential

Figure F.17 Horizontal motion limits from ISO 10137 (Modified figure based on ISO 10137:2007, Bases

for design of structures - Serviceability of buildings and walkways against vibration. Reproduced with the

permission of the International Organization for Standardization, ISO.

Table F.12

Percentage of critical damping for normal buildings

Design condition

Percent of critical damping
Concrete structures

Steel structures

Serviceability

1% to 2%

0.75% to 1%

Strength design

1.5% to 2.5%

1% to 1.5%

Dubai Building Code

Part F: Structure

F 40

The final damping values chosen shall be based on studies carried out by the

Engineer and wind specialist.
Where additional damping is provided by moving mass dampers, strength shall be

verified taking account of the risk of non-operation. The motions of the damper at

beyond service design limits shall be limited in order to maintain safety in extreme

events.

F.7.13

Design for earthquake effects

F.7.13.1

Scope

Every structure, and portion thereof (including non-structural components that are

permanently attached to structures, and their supports and attachments) shall resist

the effects of earthquake motion in accordance with ASCE/SEI 7-16.

Where any building is modified and there is change to the stiffness or mass of

more than 10%, the seismic behaviour shall be reconfirmed and ASCE/SEI 7-16

requirements shall not be followed (refer to F.7.13.13).

F.7.13.2

Seismic performance criteria

Following the requirements of ASCE/SEI 7-16 would meet the life safety structural

performance level for a probabilistic ground motion, with a 2% probability of

exceedance within a 50-year period. The enhanced ground motion parameters given

in Table F.13 shall be used for design of building structures (refer also to F.10).
Where the Owner requires a specific level of seismic performance (such as the

immediate occupancy structural performance objective), the structural and non-

structural components shall be explicitly analysed and evaluated in line with the

requirements of Section 1.3.1.3 of ASCE/SEI 7-16. Both the proposed target

performance level and ground motion parameters shall be accepted by the Authority.

The performance of the building is dependent on the adequate performance of

both the structure and the non-structural components (e.g. MEP system, façade

and vertical transportation systems, etc.). All the structure and the non-structural

components shall be included in the seismic design process, in line with the

requirements of ASCE/SEI 7-16.

F.7.13.3

Seismic ground motion values

F.7.13.3.1 Near-fault sites

There are no known active faults mapped within 15 km of Dubai, so near-fault effects

do not need to be assessed. It is assumed that the West Coast Fault is not an active

seismotectonic structure

[Ref. F.7]

F.7.13.3.2 Dubai acceleration parameters

In line with F.7.13.2, the seismic design criteria shall be modified as given in Table

F.13. These are hazard values and shall be used in ASCE/SEI 7-16 directly. No

corrections to adjust for risk-targeted ground motion shall be carried out.

Table F.13

Enhanced performance seismic ground motion parameters for Dubai (site class B)

Location

(s)

Dubai

0.51

0.18

Dubai Building Code

Part F: Structure

F 41

F.7.13.4

Site class

Based on the site soil properties, assessed in accordance with F.9, the site shall

be classified as either site class A, B, C, D, E or F in accordance with Ch. 20 and

Table 20.3-1 of ASCE/SEI 7-16. If the soil properties are not known in enough

detail to determine the site class, site class D shall be used unless the Authority or

geotechnical data determines that site class E or F soil is likely to be present at the

site.

F.7.13.5

Site coefficients and risk-targeted maximum considered earthquake

(MCE

) spectral response acceleration parameters

The MCE

spectral response acceleration parameters for short periods (S

) and at

1 s (S

), adjusted for site class effects, shall be determined by Eq. F.1 and Eq. F.2

respectively.

Table F.14 Short- and long-period site coefficients for building design in Dubai

Site class

Short-period F

Long-period F

0.80

0.90

0.80

1.296

1.50

1.392

2.24

1.684

See F.7.13.9

=2/3 S

Eq. F.3

=2/3 S

Eq. F.4

Eq. F.1

Eq. F.2

where:
S

is the MCE

spectral response acceleration parameter at short periods as taken

from Table F.13;

is the MCE

spectral response acceleration parameter at a period of 1 s as taken

from Table F.13; and site coefficients F

and F

are defined in Table F.14.

F.7.13.6

Design spectral acceleration parameters

Design earthquake spectral response acceleration parameters at short periods, S

and at 1 s periods, S

, shall be determined from Eq. F.3 and Eq. F.4, respectively.

Where the alternate simplified design procedure of Section 12.14 of ASCE/SEI 7-16

is used, the value of S

shall be determined in accordance with Section 12.14.8.1 of

ASCE/SEI 7-16, and the value for S

need not be determined.

F.7.13.7

Design response spectrum

Where a design response spectrum is required by this Part and site-specific ground

motion procedures are not used, the design response spectrum curve shall be

developed as indicated in Figure 11.4-1 of ASCE/SEI 7-16 and Section 11.4.6 of

ASCE/SEI 7-16.

F.7.13.8

Risk-targeted maximum considered earthquake (MCE

) response

spectrum

Where an MCE

response spectrum is required, it shall be determined by multiplying

the design response spectrum by 1.5.

Dubai Building Code

Part F: Structure

F 42

F.7.13.9

Site-specific ground motion procedures

A site response analysis shall be performed in accordance with Section 21.1 of

ASCE/SEI 7-16 for structures on-site class F sites.

A site response study or a ground motion hazard analysis is not required in any other

circumstances unless specifically requested by the Authority.

F.7.13.10 Seismic design category

Structures shall be assigned a seismic design category in accordance with Section

11.6 of ASCE/SEI 7-16 and Table F.15. Each building and structure shall be assigned

to the more severe seismic design category in accordance with Table F.15, irrespective

of the fundamental period of vibration of the structure, T. The provisions in Ch. 19

of ASCE/SEI 7-16 shall not be used to modify the spectral response acceleration

parameters for determining seismic design category.

Table F.15

Seismic design category based on short- and long-period response acceleration parameters

Short period value S

Risk level

Long-period value S

Risk level

I, II & III

< 0.167

< 0.067

0.167 ≤ S

< 0.33

0.067 ≤ S

< 0.133

0.33 ≤S

< 0.50

0.133 ≤ S

< 0.20

0.50 ≤ S

0.20 ≤ S

F.7.13.11 Geological hazards and geotechnical investigation

Liquefaction shall be assessed in accordance with F.9.4.5.

F.7.13.12 Damping

Damping shall be adjusted for the analysis of structures where non-linear or soil

structure interaction analysis methods are required. A damping value of 0.5% shall

be used for the convective (sloshing) component of tanks or pools. The coefficients

in Table F.16 shall be used together with Eq. F.5 and Eq. F.6 to generate design

parameters for damping other than within 5% of critical.

Table F.16

Damping adjustment factors for short- and long-period values in Dubai

Damping coefficient (

)

0.5

0.47

0.54

2.0

0.72

0.78

5.0

1.00

10.0

1.40

1.30

20.0

1.90

1.70

Eq. F.5

Eq. F.6

where:
S

is the adjusted damping parameter at a period of 1 s;

is the adjusted damping parameter at short-period;

is the damping adjustment factor for long-period; and

is the damping adjustment factor for short-period.

Dubai Building Code

Part F: Structure

F 44

F.8

Performance and serviceability requirements

F.8.1

Design basis

The basis of design shall include these aspects as a minimum:
a) strength;
b)

deflection control in concrete and steel structures;

c)  crack control in concrete structures;
d)  building movement and motions due to wind;
e)  building movement due to seismic;
f)  movement joint and building separation;
g)  vibration;
h)  lateral acceleration;
i)  fatigue; and
j)  additional requirements for transfer elements.

F.8.2

Strength

Buildings, other structures, and parts thereof, shall be designed and constructed to

support safely the factored loads in load combinations defined in this Part without

exceeding the appropriate strength limits states for the construction material.

F.8.3

Deflection control

F.8.3.1

General

Deflection limits shall be adopted that enable functional requirements to be

maintained. Limits may be governed by the requirements of internal and/or external

furniture, finishes, fixtures and fittings.
Vertical and horizontal deflections shall be within the limits specified in the

referenced design standards, as applicable, and the project-specific requirements

dictated by features such as the cladding, crane girders, members supporting

sensitive machinery, etc.

When checking for deflections the most adverse realistic combination and

arrangement of serviceability loads shall be included.

The Engineer shall verify that the adopted deflection limits will enable the functional

performance of the building to be maintained.

F.8.3.2

Concrete beam and slab deflection

Deflection limits for concrete slabs and beams shall be in accordance with Section

24.2.2 of ACI 318-19. The value of the incremental deflection (

INC

) shall not exceed

20 mm after the installation of partitions and finishes and shall be calculated in

accordance with ACI 435R and ACI 318-19.

The incremental deflection limits do not consider pre-cambering which may be used

to reduce the effect of total deflection as deemed necessary.
When evaluating the deflection of concrete structures, the detrimental effects

of cracking shall be included by modifying the stiffness (EI) for areas which have

exceeded the allowable tensile stresses. The modified EI shall be chosen based on the

extent of cracking under the design load. Default stiffness modifiers given in

ACI 318-19 may be followed for regular structures subject to approximately uniform

loads.

Dubai Building Code

Part F: Structure

F 45

F.8.3.3

Steelwork deflection limits

Deflection limits for steel structures shall conform to the requirements stipulated in

the AISC 360 and AISC design guide 3

[Ref. F.17]

The following points should also be taken into account.
a)

For cantilever elements the span length can be equal to double the cantilever

length.

The deflection limits do not take into account pre-cambering, which may be used

to reduce the effect total deflection as deemed necessary.

F.8.3.4

Post-tensioned concrete deflection control

Design for strength and serviceability requirements of members shall conform to

ACI 318-19.

Structural calculations shall verify that short- and long-term deflections, camber,

vibration frequency and amplitude are within permissible limits.
Effects of cracking should be included by modifying the stiffness EI properties

as detailed in ACI 318-19.
Most PT concrete structures combine non-prestressed reinforced concrete,

un-cracked PT and cracked PT sections. The design method shall capture the real

behaviour of the structural system by taking into consideration the stiffnesses of the

cracked and un-cracked sections.

F.8.4

Crack control in concrete structure

The significance of cracking is contained within three categories.

a) Cracks that lead to durability problems and consequently a reduction in

structural capacity.

b) Cracks that lead to a loss of serviceability of the structure

(e.g. the leakage of water or damage to finishes).

c) Cracks that are aesthetically unacceptable.

Crack widths shall be controlled in accordance with maximum crack widths defined

in the referenced codes and standards. The Engineer shall perform crack width

calculation checks in accordance with ACI 224R.

It is also recommended that basements and liquid retaining structures be classified in

relation to the degree of protection against leakage. An appropriate limit to cracking

depending on the classification should be selected by the Engineer and Owner’s

representative, paying due regard to the required function of the structure, the

intrinsic durability requirements, and soil and water properties.

CIRIA C766

[Ref. F.10]

provides guidance on aesthetically acceptable crack widths.

In the absence of more specific requirements, the following maximum crack width

limits shall be adopted.

1) For sections of the structure in contact with groundwater, the crack width

limits (w

) are defined as a function of the ratio of the hydrostatic pressure, h

to the wall thickness of the containing structure, h

i) For h

<5, w

= 0.2 mm.

ii) For h

>35, w

= 0.05 mm.

2) For intermediate values of h

, linear interpolation between 0.2 mm and

0.05 mm shall be used.

3) Section of the structure not in contact with water, w

= 0.3 mm.

4) Structural elements (such as piles) under permanent tension loads,

= 0.1 mm.

The above listed limits may be adopted providing that they do not contradict the

requirements of ACI 224R and that a proprietary waterproofing system is provided

for structural elements in contact with water in accordance with BS 8102.

Dubai Building Code

Part F: Structure

F 46

F.8.5

Crack control in restrained members

Where structural walls, columns and piles provide significant restraint to shrinkage

and temperature movements, the reinforcement provisions should be verified against

the requirements stated under either ACI 89-S15 (as in R24.4.2 of ACI 318-19)

or CIRIA C766

[Ref. F.10]

F.8.6

Drift and deformation of buildings

F.8.6.1

General

The Engineer shall assess the drift and deformation of the building considering

the whole life of the structure, including the construction stages.

F.8.6.2

Drift due to permanent gravity load

The Engineer and Contractor shall verify that any deviation from plumbs for the

building and cores, under permanent gravity loads only, conforms to the limits stated

in Section 7 of ACI 117-10.
If necessary, the Engineer shall specify any correction in the setting out of the

building. This should be validated by the Contractor, taking into account the sequence

and method of construction.

F.8.6.3

Drift and deformation due to differential vertical shortening

A non-linear static construction sequence analysis should be performed to assess

deflection and drift due to differential vertical shortening. At a minimum, the analysis

shall be performed by the Engineer and/or Contractor for the following structures:
a) multi-storey buildings with different stresses between the core and perimeter

columns;

b) structures with an asymmetrical structural plan layout and/or asymmetrical

massing;

c) buildings with stepped setbacks;
d) buildings with outriggers.

The Engineer shall assess the impact of the following design aspects:
1) elastic shortening;
2) creep and shrinkage of concrete structures where the Engineer shall refer to

ACI 209.2R and the environmental conditions of Dubai as discussed in F.7.11;

3) foundation settlements;

4) transfer elements, as discussed in F.8.10; and

5) construction stages.
The analysis methodology and parameters adopted shall be discussed and agreed

with the Authority. The Contractor shall review and validate the differential vertical

shortening analysis as it is strongly dependent on the construction stages sequence.
The Contractor shall submit the type of corrections to be implemented on-site to the

Engineer and Authority, for review and approval.

F.8.6.4

Drift and deformation due to wind

Drift and deformation due to wind shall be assessed in accordance with F.7.12.4.

F.8.6.5

Drift and deformation due to seismic

Movements of buildings due to earthquake effects shall conform to the requirements

stipulated under Section 12.12 of ASCE/SEI 7-16.

Dubai Building Code

Part F: Structure

F 47

F.8.7

Movement joints and building separation

Movement joints shall be provided, where necessary, to address the requirements of

expansion and/or deflection under load for above-ground structures. The minimum

separations between a structure and any surrounding obstructions shall not be less

than the total maximum displacement (

)

as specified in Section 12.12 of

ASCE/SEI 7-16:

F.8.8

Vibration

F.8.8.1

Steelwork

The natural frequency of steelwork floor systems for normal occupancy shall be

evaluated in accordance with AISC design guide 11

[Ref. F.18]

SCI P354

[Ref. F.19]

F.8.8.2

Concrete

Cast-in-place floor systems designed in accordance with the minimum thickness

and deflection requirements of ACI 318-19, have generally been found to provide

vibration performance suitable for human comfort under typical service conditions.

However, there might be situations where serviceability conditions are not satisfied.

For example:

long spans and open floor plans;

floors with strict vibration performance requirements such as precision

manufacturing and laboratory spaces; and

c) facilities subject to rhythmic loadings or vibrating mechanical equipment.

Further guidance can be sought in the ATC Design Guide 1

[Ref. F.13]

The performance of PT concrete floors may follow the recommendation of

TR43, Table 1

[Ref. F.11]

. For those PT concrete floors that do not follow these

recommendations, their performance should be assessed in accordance with the

dynamic assessment method defined in TR43, Appendix G

[Ref. F.11]

Precast concrete structures shall be checked for vibration as detailed in Section 9.7 of

PCI design handbook

[Ref. F.12]

=√((

)

) Eq. F.7

Where

and

are the maximum inelastic response displacements of the

adjacent structures at their adjacent edges.

=(C

max

)/I

Eq. F.8

Where:
C

is the deflection amplification factor in Table 12.2-1 of ASCE/SEI 7-16;

max

is the maximum deflection at the location required by this section, determined by

an elastic analysis; and
I

is the importance factor determined in accordance with 11.5.1 of ASCE/SEI 7-16.

Movement joints are a common source of water infiltration. Structures should be

designed below ground level, without movement joints to mitigate the risk of water

ingress. Design for construction without permanent joints below ground level can be

achieved by following the recommendations provided in the CIRIA C766

[Ref. F.10]

Dubai Building Code

Part F: Structure

F 48

F.8.9

Fatigue

Structural members that support vibrating machinery, vehicles or plant should be

checked for fatigue resistance.

Stress changes due to normal fluctuations in wind loading do not need to be included

in the fatigue check. However, where aerodynamic instability can occur, account

should be taken of wind-induced oscillations.
Where fatigue is critical, the design shall be checked in accordance with the following

codes:
a) Appendix 3 of AISC 360 for steel; and
b) ACI 318-19, ACI 215R and ACI 408.2R for concrete.

All design details shall be fully defined, including clear specification of the

workmanship and quality assurance tests.

F.8.10

Transfer elements

Any beam, slab or truss structure used to redirect the vertical gravity or lateral load

path of upper stories to the vertical structure of the lower stories shall be treated as

a transfer element.

Such elements are typically used where a change of use on a floor dictates a different

column or wall arrangement, or to accommodate architectural features.

Transfer structures have significant design, cost, material and construction schedule

implications, requiring careful consideration of construction logistics, as well as

consideration of the impact of long-term deflections of the transfer members and

supporting elements. As such, transfer structures should be avoided where possible.

The following shall be included in the design of transfer elements.
a) Transfer beams are to be supported on at least two direct supports.
b) Eccentricity between the column axis and the longitudinal axis of the beam is not

permitted. The load transferred to the planted column, transfer beam or slab shall

not be less than the loads calculated by manual method (tributary area).

c) Any structural elements supporting planted/floating columns that might cause

a progressive collapse are to be included as a key element. Reinforcement shall

be detailed to facilitate robustness by means of provision of adequate peripheral,

vertical and horizontal ties.

d) The entire length of the supporting columns shall be included as critical length

and the stirrups shall be spaced closely to provide effective confinement for the

columns.

e) Structural systems elements of the planted portions of the structure shall

have redundancy to provide alternative load paths in the case of failure of any

structural member, as discussed under F.5.5.

f) Any structural members or element that do not fall under the purview of this part

should be analysed and designed for various possible critical combinations.

g) Transfer structure shall be capable of withstanding the reactions from any

attached building components. The reactions should be the maximum values

that might reasonably be transmitted considering the strength of the attached

component and its connection.

h) The Engineer shall check that the deflections of the structural members

supported by the transfer elements are within the deflection limits specified in

F.8.3.

Dubai Building Code

Part F: Structure

F 49

F.9

Geotechnics

F.9.1

Introduction

This section provides minimum geotechnical

requirements that are appropriate for the geology,

stratigraphy, geotechnical and groundwater conditions

of Dubai. A major characteristic of the ground in Dubai

is its calcareous origin for both soils (e.g. calcareous

sand) and soft calcareous rocks, with clay minerals of

various expansion potential. Groundwater is saline with

chlorites and sulphates that make a very aggressive

environment for concrete and reinforcement in the

ground.
The geotechnical requirements and design aspects are

discussed in F.9.3 to F.9.5.

The geotechnical design of buildings shall be based

on the requirements stated herein and the referenced

standards (see Figure F.18). This section should be also

read in conjunction with all the other relevant sections

of this Part.
Additional studies are expected for unusual

constructions, and might result in a variation from

these requirements which would require approval from

the Authority.
Geotechnical design and construction shall conform

strictly to the current health and safety regulations

issued by the Authority.

BS EN 1997-1
General rules

Other Eurocodes

BS EN ISO 14689

Identi

cation of rock

BS EN 1993-5

Steel piling

BS EN 1536
Bored piles

BS EN 14199

Micro piles

BS EN 12699

Displacement piles

BS EN 1997-2

Ground investigation

BS EN ISO 22476

Field testing

BS EN ISO 14688

Identi

cation of soil

BS EN ISO 22475

Groundwater

BS EN ISO 17892

Laboratory testing

BS EN ISO 22282

Geohydraulic testing

UK NATIONAL

ANNEX

UK NATIONAL

ANNEX

UK NATIONAL

ANNEX

EXECUTION OF SPECIAL

GEOTECHNICAL WORKS

GEOTECHNICAL

INVESTIGATION & TESTING

GEOTECHNICAL DESIGN

Figure F.18

Suite of standards for geotechnical investigation and testing, design and execution of piling works.

The geotechnical site investigations and testing shall

be undertaken by the geotechnical laboratory. All

geotechnical reports submitted by the geotechnical

laboratory shall be reviewed and approved by the

Engineer who witnessed the execution of soil testing.
Any geotechnical design packages submitted and

executed by the Geotechnical Specialist Contractor

shall be reviewed and approved by the Engineer.

All the geotechnical design works and site investigation

reports shall be submitted to the Authority for the

necessary approval.
All the geotechnical design and execution packages

shall be undertaken by a qualified Geotechnical Civil

Engineer.

Dubai Building Code

Part F: Structure

F 50

F.9.2

Standards

Geotechnical site investigations and geotechnical works shall be designed to meet or

exceed the minimum requirements of the codes and standards listed in F.3.

F.9.3

Geotechnical site investigation

F.9.3.1

General

Geotechnical site investigations shall be planned and carried out in accordance with

BS 5930, BS EN 1997-2:2007 and the associated UK NA, BS 1377 and BS 10175.

As indicated in BS 5930, the primary objectives of a geotechnical investigation are as

follows:
a) to assess the general suitability of the site for the proposed works;
b) to enable an adequate and economic design to be prepared;
c)

to foresee and provide against difficulties that may arise during construction due

to ground and local conditions; and

d) to predict any adverse effect of the proposed construction on neighbouring

structures.

A schematic representation of the geotechnical site investigation is illustrated in

Figure F.19.

Figure F.19

Schematic organization of a site investigation

DECISION TO DEVELOP SITE AND

CARRY OUT SITE INVESTIGATION

DESK STUDY

FIELD WORKS

AND TESTS

SAMPLES

LABORATORY

TESTING

WALK-OVER SURVEY

GEOTECHNICAL INVESTIGATION

FACTUAL REPORT (GIFR)

GEOTECHNICAL INTERPRETATIVE

REPORT (GIR)

DESIGN

GROUND INVESTIGATION

•

Preliminary investigation

•

Main investigation

Dubai Building Code

Part F: Structure

F 51

F.9.3.2

Geotechnical desk study

The geotechnical desk study shall provide a

conceptual model of the site based on all the available

morphological, geological, hydrological, geotechnical

information, and land use history from public sources

and technical literature. The extent of the study will

vary according to the nature of the project and the

anticipated ground conditions.

F.9.3.3

Planning geotechnical investigation

The extent of the geotechnical investigation is

dependent on the complexity, size and criticality of

the development. Guidance on the spacing and depth

of the investigation points is given in Annex B of BS

EN 1997-2:2007, and the associated UK NA. Soil

investigation for any building shall be defined by:

a) the location of the building;
b) the magnitude of the imposed loads;
c)

the number of floors;

d)  the shape of the building;
e)  previous uses of the land;
f)  terrain surface features;
g)  geological features; and
h)  surface water drainage.

F.9.3.4

Geotechnical on-site investigations

The requirements for geotechnical soil investigations

are provided in BS EN 1997-2 and the associated UK

NA and BS 5930. As a minimum, the investigations

shall include the following:
a) non-intrusive investigations (mapping, geophysics);
b) intrusive investigations (boreholes, trial pits,

observation wells);

c) sampling of soils, rocks and groundwater;
d) in-situ testing including:

1)  standard penetration test (SPT);
2)  cone penetration test (CPT);
3)  pressure meter;
4)  permeability;
5)  in-situ strength; and
6)  deformability.

The depth of investigation shall extend to at least three

times the shortest plan dimension of the proposed

foundation as specified in Annex B of BS EN 1997-

2:2007.

The minimum number of boreholes shall conform to

BS EN 1997-2:2007, the associated UK NA and the

following:
1) for high-rise buildings: more than G+12, one

borehole per 750 m

and a minimum of five

boreholes;

2) for buildings: less than G+12, one borehole per

750 m

and a minimum of three boreholes; and

3) for large structures: 60 m grids between boreholes

required.

An example of the organization and phasing of the on-

site investigation is given

in Figure F.20.

Figure F.20

Typical organization and phasing of on-site investigation

RB-1

RB-2

RB-3

RB-4

DMP-1

DMP-2

CP-1

CP-3

CP-2

Key

Soil test boring with SPT

CPT

Dilatometer test

01: Building Layout

02: Utilities line

03: Topographical contour line

RB-1

RB-2

RB-3

RB-4

DMP-1

DMP-2

CP-1

CP-3

CP-2

Dubai Building Code

Part F: Structure

F 52

F.9.3.5

Geotechnical laboratory testing

The requirements for geotechnical soil investigations shall conform to BS 1377,

BS EN 1997-2:2007 and the associated UK NA and BS 5930. The following list

indicates a minimum level of laboratory testing:

a) soil classification/index tests;

b) soil engineering properties tests (strength, stiffness, deformability);

c) rock classification/index tests;

d)  rock engineering properties tests; and
e)  soil, rock and groundwater chemical tests.
Soil tests shall be conducted in laboratories licensed and approved by the EIAC.

All soil tests shall conform to EIAC approved standards.

F.9.3.6

Geotechnical reporting

Throughout, and particularly at the end of the investigation, the geotechnical

laboratory shall issue the geotechnical investigation factual report (GIFR) and

geotechnical interpretative Report (GIR), which are then reviewed and approved

by the Engineer.

For major developments and special projects, the GIR should be issued by the

Engineer based on the GIFRs issued by the geotechnical laboratory.
The following items shall be as a minimum included in the GIFR:

clear definition of the site, general topography;

b)  site plan/drawing with all as-completed investigation location coordinates;
c)  time and duration of on-site investigations;
d)  meteorological/weather conditions at the time of investigations;
e)  the use and state of the site at the commencement of the on-site investigation;

accurate account of the equipment specified, mobilized and used for the on-site

investigation and in-situ testing including the methodologies and standards

adopted;

g) all levels of topography including any lidar scans or other means of obtaining

point cloud data, all site investigation points (e.g. trial pits, boreholes, CPTs, SPTs),

all stratigraphic levels, groundwater levels recorded and similar, to be specified in

the DMD;

h)  groundwater monitoring level, period and frequency;
i)  groundwater temperature;
j)  borehole and trial pit logs with coordinates and description of encountered strata,

levels and types of all specimens taken (soil, rock and groundwater);

k) qualitative and quantitative description of boring (e.g. rock quality designation,

total core recovery, etc.);

l) levels and results of all in-situ tests (e.g. SPT);
m) borehole logs shall be supplemented with all relevant laboratory tests that

facilitate classification of strata (e.g. uniaxial compressive strength);

n) colour photos of borehole cores, including depth labels and colour chart;
o) full documentation of all performed laboratory tests, with suitable illustrative

plots/diagrams;

ground profile plot with key information of stratigraphy and groundwater level

(see Figure F.21).

Dubai Building Code

Part F: Structure

F 53

Figure F.21

Typical geological section

Key

01-07: Boreholes

08: Ground fill

09: Sand

10: Sandstone

11: Conglomerate

12: Calcisiltite

The GIR shall include the following details as a minimum when submitted to the

Authority:
1) details of the recommended foundation system, with allowable bearing capacity,

modulus of sub-grade reaction and allowable settlement;

2) provision to mitigate the effects of expansive and collapsible soils in accordance

with the recommendations provided in Ch. 32 and 33 of the ICE Manual of

geotechnical engineering (vol. I)

[Ref. F.20]

;

3) provision to mitigate the effect of soil liquefaction, which shall be assessed as

stipulated in F.9.4.5;

4) provision to mitigate the effect of soil settlement and loads from adjacent plots;
5) various seismic parameters for the uppermost 30 m, in accordance with the

specified codes;

6) piles working load capacity under compression and tension for different sizes, at

varying depths and effective length (all levels should be in DMD);

if applicable, recommendations for pile groups with modification factors for load

and settlement;

8) values of modulus of elasticity of soil (E

);

horizontal modulus of sub-grade reactions (K

);

10) constant of horizontal sub-grade reaction (n

);

11)

vertical spring constants (K

);

12) Poisson’s ratio;
13)

piles stiffness (K

);

14) optimal spacing between piles within a pile group;

08 09 10 11

Dubai Building Code

Part F: Structure

F 54

15) soil parameters required for shoring and basement wall design, such as:

i) average bulk density;
ii) angle of shearing resistance;
iii) cohesion;
iv)

coefficients of soil pressure at rest (K

) pressure; and

coefficient of active and passive soil pressure for all soil layers.

16)

soil classification and index test results (particle size distribution, plasticity

chart);

17)

rock classification and index test results;

18)  permeability of soil and rock layers;
19)  plan showing boreholes, in-situ test location and coordinates;
20)  water table level (in DMD) and temperature;
21)  laboratory test results on soil and groundwater samples for the presence

and concentration of pH, sulphate and chloride, or any other chemicals or

components that might affect the structure;

22)  type of cement based on the chemical test results of soil types;
23)  summary of soil parameters;
24)  subsoil conditions and description;
25)

recommendation on the earth work, excavation, filling and compaction; and

26)

recommendations for suitability of site material to be used as fill material.

F.9.4

Geotechnical design

F.9.4.1

Earthworks (excavation and filling)

Excavation works shall be designed in accordance with BS EN 1997-1:2004 and the

associated UK NA and BS 6031. The design recommendations of Ch.23 of the ICE

manual of geotechnical engineering (vol. I)

[Ref. F.20]

should also be followed for the

slope stability analysis.
The Geotechnical Specialist Contractor shall provide slope stability analysis for any

open cut excavation (see Figure F.22).

Figure F.22

Open cut excavation

Dubai Building Code

Part F: Structure

F 55

The Geotechnical Specialist Contractor shall design remedial actions when slopes

display signs of instability or the geotechnical analysis confirms the risk of failing.

The list below presents some of the common slope stabilization techniques which

may be used in Dubai.
a) Regrading of the slope. If the available land plot permits, the slope can be

regraded to reduce the slope angle.

b) Drainage. Deep drains are perforated plastic tubes that can be embedded into the

slope to reduce the pore water pressure.

Retaining wall. Retaining walls shall be designed in accordance with F.9.4.3.

d) Soil nailing. An in-situ reinforcement technique consisting of drilling or driving

steel bars into the soil mass (see Figure F.23 and Figure F.24). The soil nails are

secured to steel plates at the surface and optional erosion and vegetation control

geosynthetic mesh can be placed over the slope face. If the soil is loose on the

surface, concrete can be sprayed to cover the slope face (see Figure F.23). Further

guidance can be sought in Ch. 74 of the ICE manual of geotechnical engineering

(vol. II)

[Ref. F.20]

Filling material. The material used for backfilling purposes shall be of selected fill

composed of a sand/granular mixture. The plasticity index of the backfill material

should not exceed 10%. The maximum particle size of backfill material shall not

exceed 75 mm. The percentage passing through a 75 mm sieve shall not exceed

20%. The organic materials content shall not exceed 2% and the water-soluble

salt content shall not exceed 5%

Compaction. The backfill materials shall be placed in layers of thickness 150 mm

to 250 mm and compacted to not less than 95% of the maximum dry density.

The Engineer shall state whether the material available on site could be used for

general backfilling or not after performing the necessary analysis.

Figure F.23 Soil nailing detail (Modified figure based on Figure 2.1 from CIR 7 FHWAO-IF-03-017, Geotechnical

Engineering Circular No.7, Soil Nail Walls, 2003, United States Department of Transportation Federal Highways

Administration)

Key

01: Permanent facing (e.g.

cast-in-place reinforced

concrete)
02: Temporary facing

(shotcrete)
03: Geocomposite strip drain
04: Grout
05: Steel bar
06: Welded wire mesh
07: Reinforcement
08: Bearing plate
09: Washers
10: Nail head
11: Studded head

Dubai Building Code

Part F: Structure

F 56

Figure F.24

Installation of soil nailing system

F.9.4.2

Foundations design

F.9.4.2.1 General

The geotechnical design of foundations shall be undertaken in accordance with BS

EN 1997-1:2004 and the associated UK NA.
The typical foundation systems in Dubai are illustrated in Figure F.25

Key

01: Strip footing

02: Isolated footing

03: Stepped footing

04: Combined footing

05: Mat foundation

06: Deep foundation system

with piles and pile cap

07: Retaining and buttressed

wall foundation

08: Column

09: Piles

10: Pile cap

11: Stem

12: Toe

13: Key (optional)

14: Heel

15: Counterfort

Dubai Building Code

Part F: Structure

F 57

F.9.4.2.2 Shallow and raft foundations

The geotechnical design of shallow foundations (i.e. isolated, strip, stepped, combined

footing and raft) shall be in accordance with Section 6 of BS EN 1997-1:2004 and

the associated UK NA.

The most common limit states for spread foundations are:
a) loss of overall stability;
b) bearing resistance failure (the equations for bearing capacity are given in Annex

D, BS EN 1997-1:2004 and the associated UK NA);

c)  failure by sliding;
d)  combined failure in the ground and in the structure;
e)  structural failure due to foundation movement;
f)

excessive settlements (refer to Annex H of BS EN 1997-1:2004 and the

associated UK NA);

g) excessive heave due to swelling, frost and other causes; and
h) unacceptable vibrations.

Design of the permanent concrete structural elements shall follow F.6, F.8 and

ACI 318-19.

Raft foundations shall be designed as “rigid” unless a specific geotechnical model and

calculation are adopted to validate the design approach.

F.9.4.2.3 Deep and piled foundations

The geotechnical design of deep and piled foundations shall be in accordance with

Section 7 of BS EN 1997-1:2004 and the associated UK NA.

The following limit states shall be included in the design of deep foundations:
a) loss of overall stability;
b) bearing resistance failure of the pile foundation;
c)

uplift or insufficient tensile resistance of the pile foundation;

d)  failure in the ground due to transverse loading of the pile foundation;
e)  structural failure of the pile in compression, tension, bending, buckling or shear;
f)  combined failure in the ground and in the pile foundation;
g)  combined failure in the ground and in the structure;
h)  excessive settlement;
i)  excessive heave;
j)  excessive lateral movement;
k)  unacceptable vibrations; and
l)  liquefaction effects on piles.
The load-bearing mechanism (i.e. end bearing, friction, friction with end bearing piles)

shall be recommended in the GIFR. In particular, the end bearing capacity shall be

agreed with the Authority before the design is commenced.

Design of the permanent concrete structural elements shall be in accordance with F.6,

F.8 and ACI 318-19.
The design criteria listed in Table F.17 are applicable to reinforced concrete

foundations on piles.

Dubai Building Code

Part F: Structure

F 58

Design criterion

Minimum requirement

Pile design: general

Ensure pile design allows for both gravity and lateral loads.
Piles to be designed for out of verticality tolerance of 1/75.
Piles to be designed for eccentricity of vertical load of 75 mm.

Factor of safety shall be at least 2.5, unless geotechnical model

and geotechnical calculations based on the geotechnical site

investigation are provided.
Minimum rock socket length of three times pile diameter.
The use of bentonite is not recommended. If it is used, the shaft

capacity shall be reduced.
Pile caps shall be designed in accordance with the requirements

specified under ACI 318-19 and the CRSI design

handbook

[Ref. F.8]

Crack width limit for tension

piles (w

)

0.2 mm considering the tension load.
0.1 mm considering the uplift load due to permanent tension load

(i.e. groundwater uplift, out of balance gravity loads).

Geotechnical design parameters The recommendations provided in the GIR shall be followed unless

a specific geotechnical model and geotechnical calculation are

developed.

Materials test reports

(aggregate, steel, concrete, etc.)

To be implemented by laboratories approved by DM or EIAC.

Minimum bar diameter

12mm

Minimum number of bars

Six bars evenly spaced.

Minimum percentage of

reinforcement

To be provided for the full length of the piles in order to provide

ductility and in accordance with Table 18.13.5.7.1 of ACI 318-19.

Minimum stirrup reinforcement Bars of 10 mm diameter for all the piles.

The top region of the pile below the caps or raft, shall be confined

effectively with closely spaced stirrups, for a length of three times

the pile diameter.
Stirrup reinforcement shall be in accordance with Table 18.13.5.7.1

of ACI 318-19.

Design criterion

Minimum requirement

Minimum design of horizontal/

lateral force

For the lateral pile design, the following requirements shall be

included:
a)

minimum 5% of pile capacity and not less than the horizontal

loads resulting from the superstructure and foundation

analysis;

b) moments due to out of position (75 mm) piles; and
c) horizontal force due to verticality (1/75).
The above design (a) may be excluded if geotechnical calculations

and geotechnical models are provided and the following items are

included in the design:
1) isolated temperature changes within raft, and temperature

distribution from column to raft;

2) detailed pile group assessment considering soil-structure

interaction, building stiffness and foundation stiffness;

3)  moments due to slab dishing;
4)  kinematic effects of earthquake loading;
5)  sensitivity checks should piles be constructed out of position;
6)  embedment of raft; and
7)  lateral load path analysis and load transfer into the raft slab.

Rational study of pile spacing

not available

Minimum pile spacing shall be 2.5 times the diameter.

Pile stress under compression

load

Maximum 25% of concrete strength.

Lateral stiffness of piles

50% to 100% of vertical stiffness.
Any other percentage (such as 10% to 15% of vertical stiffness)

shall be justified by geotechnical models and calculations including

the piles lateral group effect.

Vertical stiffness of piles

The impact of subsidence of the piles group on vertical stiffness,

as well as its effect on the raft and piles, shall be validated by

geotechnical models and calculations.

Table F.17

Piles foundation minimum design criteria

Dubai Building Code

Part F: Structure

F 59

F.9.4.3

Shoring and earth retaining system

F.9.4.3.1 General

The geotechnical design of earth retaining systems shall be performed in accordance

with Section 9 of BS EN 1997-1:2004+A1:2013 and the associated UK NA. Design

of the concrete structural elements shall follow F.6, F.8 and ACI 318-19.

Shoring systems and retaining structures are deemed to be temporary if the design

life of the system is less than two years. They shall not be deemed to be part of

the permanent structures and a physical segregation shall be provided between

temporary and permanent structural systems.
The shoring and retaining systems shall be designed to retain the soil and actual

groundwater pressure (including tidal effect).

NOTE: Shoring and earth retaining systems typically used and accepted in Dubai are

as follows:
a) non-watertight shoring systems:

1)  soldier piles with lagging system/king post walls;
2)  contiguous pile walls;
3)  slurry walls;

b) watertight shoring systems:

1)  secant pile walls;
2)  diaphragm walls;
3)  sheet piles;

c) bracing for temporary earth retaining systems:

1)  anchors;
2)  rakers; and
3)  struts.

Alternative techniques specified in accordance with international codes and

standards may also be accepted.
The shoring and bracing systems are further described in Ch. 62, 63 and 64 of the

ICE manual of geotechnical engineering (vol. II)

[Ref. F.20]

Dubai Building Code

Part F: Structure

F 60

F.9.4.3.2 Required shoring systems

Table F.18 should be followed for different depths of excavation and site conditions.

Type of shoring system

Permitted under following criteria

All types

up to 5 m deep excavation;
one basement.

All types, except soldier pile

with lagging

up to 9 m depth and no buildings in the adjacent plots.

Shoring system preventing

water leakage

presence of buildings in the adjacent plots;
high groundwater level;
proximity to water bodies.

Table F.18

Type of shoring system

It is possible to adopt shoring systems other than those in Table F.17, based on

the soil examination report, groundwater level, presence of water sources, adjacent

buildings and surrounding constructions.

The minimum requirements listed in Table F.19 shall be included in the design of

temporary shoring systems.

Design criteria

Minimum requirement

Minimum additional loads

Additional uniform distributed load of 20 kN/m

shall be taken into

consideration in proximity to roads and land plots. The additional

surcharge load needs to be assessed based on the actual conditions

on-site and adjacent structures.

Minimum distance between

anchors

1.2 m

Maximum length of anchors

10 m

Minimum length of anchors

3 m

Maximum lateral displacement

40 mm

Unplanned excavations

Retaining walls shall be designed assuming presence of unplanned

excavations in front of the wall, with depth of not less than 10%

of the total height of vertical walls, or 10% of vertical distance

between the lowest anchor and the bottom of the excavation, but

not less than 0.5 m.

Heave

The geotechnical design shall assess heave if swelling and

collapsible soils have been identified in the GIFR. Further guidance

can be sought in Ch. 32 and 33 of the ICE Manual of geotechnical

engineering (vol. I)

[Ref. F.20]

Table F.19

Minimum requirements for earth retaining system

Dubai Building Code (2021) - page 14