While it is not explicitly required, site specific response spectra, is recommended for soil-structure interaction. Because the soil structure interaction effects alter the foundation input motion or seismic demands on a structure due to changes in damping, it is important to have an accurate representation of the free field motion at the site. Site specific response spectra can even be developed at the foundation depth, directly incorporating embedment effects instead of using the equations in Chapter 19 to estimate those effects. 8.3 A four story reinforced concrete shear wall building with one basement will be used to illustrate the soil structure interaction provisions of the The building is located in a region of very high Standard. seismicity, within 5 miles of an active fault with subsurface material that would be characterized as Site Class D. The average shear wave velocity for 100 feet below the ground is 800 ft/s based on the geotechnical investigation at the site. A site specific response spectrum was developed in accordance with Chapter 21 of the and shown below in Figure 8-1. are 1.0 and 0.71 Standard SDS and SD1 respectively, placing the building in Seismic Design Category E. Figure 8.3-1: Site Specific Spectra The building used for the example is approximately 53 feet tall and the basement is 15 feet below grade. Figure 8-2 shows an elevation of the building. The building is rectangular with a north south dimension of 180 feet and an east-west dimension of 150 feet. Floor slabs are reinforced concrete flat plates and the columns are rectangular cast-in-place concrete situated on spread footings. The lateral forces are resisted by cast-in-place special reinforced concrete shear walls. There is a reinforced concrete wall around the entire basement. The interior walls and columns are founded on spread footings and the basement wall is founded on a continuous strip footing. Figure 8-3 shows a foundation plan of the building. The weight of each floor is summarized in Table 1. Table 1: Story Weight Story Weight Fourth 4,000 kips Third 4,100 kips Second 4,100 kips First 4,400 kips
While it is not explicitly required, site specific response spectra, is recommended for soil-structure interaction. Because the soil structure interaction effects alter the foundation input motion or seismic demands on a structure due to changes in damping, it is important to have an accurate representation of the free field motion at the site. Site specific response spectra can even be developed at the foundation depth, directly incorporating embedment effects instead of using the equations in Chapter 19 to estimate those effects. 8.3 A four story reinforced concrete shear wall building with one basement will be used to illustrate the soil structure interaction provisions of the Standard. The building is located in a region of very high seismicity, within 5 miles of an active fault with subsurface material that would be characterized as Site Class D. The average shear wave velocity for 100 feet below the ground is 800 ft/s based on the geotechnical investigation at the site. A site specific response spectrum was developed in accordance with Chapter 21 of the Standard and shown below in Figure 8-1. SDS and SD1 are 1.0 and 0.71 respectively, placing the building in Seismic Design Category E. Figure 8.3-1: Site Specific Spectra The building used for the example is approximately 53 feet tall and the basement is 15 feet below grade. Figure 8-2 shows an elevation of the building. The building is rectangular with a north south dimension of 180 feet and an east-west dimension of 150 feet. Floor slabs are reinforced concrete flat plates and the columns are rectangular cast-in-place concrete situated on spread footings. The lateral forces are resisted by cast-in-place special reinforced concrete shear walls. There is a reinforced concrete wall around the entire basement. The interior walls and columns are founded on spread footings and the basement wall is founded on a continuous strip footing. Figure 8-3 shows a foundation plan of the building. The weight of each floor is summarized in Table 1. Table 1: Story Weight Story Weight Fourth 4,000 kips Third 4,100 kips Second 4,100 kips First 4,400 kips
121715_DesignExamples1-8.docx