42352 Seismic design category The maximum ground acceleration used to establish

# 42352 seismic design category the maximum ground

• 164

This preview shows page 39 - 42 out of 164 pages.

4.2.3.5.2 Seismic design category The maximum ground acceleration used to establish earthquake loads in designing structural elements are: a) 0.3g for Trinidad; and b) 0.4g for Tobago. The values for maximum ground acceleration are based on a 2% probability of exceedance in a 50 year period. NOTE For detailed design for earthquake loads, the input of a registered professional should be obtained. 4.2.3.6 Deflection limits The permissible deflection of any structural member under live load shall be in accordance with the limits in Table 4-3.

Subscribe to view the full document.

PCTTS 599: 20XX 32 Table 4-3 Maximum deflection under live load Structural member Limit Floor slab, structural beam and ceilings L/360 All other structural members L/240 Rafters and purlins L/180 Interior walls and partitions H/180 NOTE: L = span length; H = span height 4.2.3.7 Lateral load transfer 4.2.3.7.1 Principle Wind and earthquake forces introduce horizontal loads in the superstructure that are transferred to the foundation. This transfer occurs in two steps: Step 1: Transfer of the horizontal load to the appropriate wall or framed structure from either of the following: a) wind on the walls and roof of the structure; or b) acceleration of mass located everywhere in the superstructure Step 2: Transfer of the load from the top to the bottom of the wall (or superstructure) and foundation. For the purposes of this Guide: a) horizontal transfer is done by horizontal diaphragm or horizontal beam and slab; and b) vertical transfer is done by shear panel, cross bracing, or framed structure. 4.2.3.7.2 Diaphragm action Floor, roof or ceiling assemblies may be constructed with the necessary stiffness and load path continuity to distribute wind and earthquake loads to lateral support subsystems. In this role, the floor, roof and ceiling surfaces act as horizontal beams or diaphragms spanning lateral support points. The use of a floor, roof, or ceiling assembly as a diaphragm requires both strength and stiffness properties and the development of connections to transfer the diaphragm force. NOTE The above considerations are very important to complete the role and action of the shear panels.