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Eugene City Hall R32.19.04 Rev. B. September 9, 2003 <br /> <br />to roof, #5 spiral reinforcing at 2" pitch at basement level). Once the elastic capacity of <br />these columns is reached in lateral drift, the exterior concrete will rapidly spall and the <br />vertical steel will buckle soon thereafter. Serious structural damage and partial collapse <br />will occur at the first floor level at seismic loads that impose ductility demands much <br />over 1.5 to 2. <br /> <br />Figure 2-13 shows the typical block wall construction used for all four of the office <br />wings. Drawing review (1995b) suggests that these walls are lightly reinforced (#4 bars at <br />48"), but actual reinforcement might differ. As outlined in Section 5, a test program to <br />confmn the reinforcement, interior grouting and wall connections to floor / roof is <br />recommended as part of a final design retrofit effort. <br /> <br /> Figure 2-13. Block Walls at Main Level <br /> <br /> The roof over the four office wings is composed of a reinforced concrete waffle slab with <br /> gravel topping (Figure 2-14). There are also HVAC heat exchangers pieces of equipment <br /> atop the roof; access panels were not opened to con£u-m how these were restrained to the <br /> roof- likely they are adequate. <br /> <br /> There is also a microwave communication tower atop the roof. Assuming the tower was <br /> designed to accommodate ice and severe wind loading, the tower should be adequate for <br /> seismic loading up to Z=0o3g or even larger. <br /> <br /> G&E Engineering Systems Inc. Page 11 <br /> <br /> <br />