Abstract
The paper deals with the design requirements for reinforced concrete diaphragms. Although diaphragms are primary members of the seismic force resisting system, ductile detailing of diaphragms is not considered to be required. While the design of diaphragms in regular framed buildings is straightforward, the analysis of transfer diaphragms involves more complex design criteria. Special considerations related to precast diaphragms are dealt with in more detail.
Highlights
For the purposes of this paper, diaphragms are defined as structural members which distribute seismic forces to the horizontal force resisting system
The paper is confined to reinforced concrete diaphragms, both cast-in-situ and precast, and includes situations where in-situ toppings are laid on prestressed floor units
Diaphragms are generally listed as primary members of the seismic force resisting system, and as such they have to be carefully considered in the design of the total structure
Summary
For the purposes of this paper, diaphragms are defined as structural members which distribute seismic forces to the horizontal force resisting system. In any design for forces below the expected elastic response levels, some of the primary members - beams, columns or shear walls must dissipate seismic energy No such action is (or should be) required of diaphragms. In buildings requiring type 2 diaphragms, the behaviour of the primary elements is very much dependent on the transfer diaphragm maintaining its assumed strength and stiffness throughout any seismic attack. These diaphragms should be designed for forces F ^ corresponding to the probable yield capacity of the primary system.
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