SOLVING FOR TOTAL SEISMIC DESIGN LOAD

The different procedures for solving base shear all contain total seismic design load, W. Although this is mainly the dead load computed from the structural configuration, there are cases where W is a combination of loads.

Warehouses and stores consider a combination of dead load of the building and 25% of the live load. This is due to inventory placed and stacked in the structure.

                                                           

Total seismic design load only considers the members on top of the gradeline. In cases where another support is placed above the gradeline, the total seismic design load would change and adopt to the level on top of the support.

credits from ArchDaily

Unit weight of construction materials are considered in computing the dead load (204-1).

• Reinforced concrete, stone, including gravel   =      
• Exterior and partition walls are measured in   or kPa. Note that values in the table are given for unplastered  walls, thus additional 0.24 kPa for each phase if plastered. Computation for the weight of masonry walls would have to multiply the tributary height by the unit weight.

                    

Dead Loads adopted in the Philippines:

   

MATERIAL	DRY UNIT WEIGHT
Structural Steel	76.8 kN/cu.m (490pcf)
Reinforced concrete	23.54 kN/cu.m (150pcf)
Slab per 10mm thk	2.35 kPa (50.0psf)
Floor finish and toppings	1.20 kPa (12.5psf)
Ceilings and utilities	0.24 kPa (5.0psf)
Exterior wall (150mm thk CHB)	2.80 kPa (57.0psf)
Interior Partitions (100mm thk CHB)	2.00 kPa (42.0psf)
Waterproofing/topping	1.20 kPa (12.5psf)
Movable partition	1.00 kPa (20.0psf)

PROCEDURE ON COMPUTING DEAD LOADS

1. Take the volume of slabs and beams and multiply with the unit weight.

2. The weight of the columns and walls are computed using the tributary height. The weight of columns (and walls) for the second floor considers the weight of the columns using the lower half (half of the first floor) and the upper half (half of the second floor).

3. Take the summation of loads per floor.

RELATED ARTICLES:

Design of base shear
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Identifying the Importance Factor, I
What do Seismic Zones mean?
Philippine Seismic Source Types
Near Source Factors and Seismic Coefficient
Soil Profile Types
Elastic Fundamental Period of Structures