Page 36 - Building Regulation and Design Guidelines - Structural (Grey Code)

SECTION: 2 STRUCTURAL DESIGN GUIDELINES – BUILDING STRUCTURES SECTION: 2 STRUCTURAL DESIGN GUIDELINES – BUILDING STRUCTURES
2.5.2.3 GENERAL CONSIDERATIONS
1. Where the structure is composed of a flexible upper
portion and lower stiffer basement/podium, the seismic
scale factor shall be calibrated at foundation level to
design the basement elements and at top of basement to
design the tower elements.
2. The augmented section modifiers could be used to
check the maximum drift and vibration acceleration only
as permitted by ACI, provided that the designer has to
estimates the degree of cracking and comply with the
serviceability limit state at the adopted design service
loads.
3. Permanent drift due to gravity loads to be checked and
shall be eliminated or minimized with proper technical
arrangement.
4. All structural framing elements and their connections, not
required by design to be part of lateral–force-resisting
system, shall be designed to be adequate to maintain
support of design dead plus live loads when subjected to
the deformation caused by seismic forces.
5. Effects of axial long term shortening due to elastic,
shrinkage and creep effects shall be investigated and
accounted for in the design and construction. If measures
to compensate for the effects of differential shortening
are taken, consultant shall include such information on
engineering drawings and relevant documents.
6. Manual take down of gravity loads for all key vertical
elements to be compared with resulting loads from
analyzed model.
7. Loading and Design shall be carried out in compliance
with the code that the governing load combination was
derived from.
8. Calculation of effects of accidental eccentricities and load
reductions shall be consistent with the code used for the
structural design.
9. Thermal effects shall be evaluated based on realistic
temperature distribution. Seasonal temperature change
shall not be less than 25 deg. C or in accordance
with credible local climate record. This effect shall be
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considered in design of vertical and horizontal members.
In plane section modifiers for slabs shall be reduced to
account for concrete cracked section area as per the code
governing the design.
10. Structural design shall accommodate shrinkage, creep and
thermal strains by providing appropriate reinforcement or
specifying control or expansion joints. Expansion joints
shall satisfy seismic requirements of relevant code.
11. Floor slabs shall be designed to be adequately supporting
the entire construction loads from the next slab without
compromising the ultimate or/and service limit states
requirements.
12. Transfer element design shall be confirmed by alternative
design method.
13. For dead loads & earth pressure/uplift load combinations,
the loads shall be factored as per clause 1909.2, UBC1997.
14. Individual pile caps and isolated footings subjected to
seismic forces shall be interconnected by ties. Such ties
shall be designed as per clause 1807.2, UBC 1997.
15. Third party structural review is required for
specific structures as classified in CED circular Ref.
CIRCULAR-52027/2009/sk dated 26-04-2009.
2.5.2.4 SERVICEABILITY LIMITS
1. All buildings shall be designed to limit maximum drift
under 50 years wind load to 1/500 of building height.
2. All buildings shall be designed to limit inter-story drift to
1/500 of the story height and not more than 10mm under
serviceability of 10 years wind. If no wind tunnel test results
are available, 10 years serviceability wind speed of 38 m/s
can be adopted in Dubai for inter-story drift calculations.
Inter-story drift due to seismic shall be assessed and shall
not exceed the limitations of clause 1630.10, UBC 1997.
3. Adequate provisions shall be adopted to eliminate risk of
damage to non-structural elements due to inter-story drift
and long term deflection of beams and slabs.
4. Wind induced vibration due to 10 years wind shall be
limited to 15 milli-g for residential and hotel buildings
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