17.6.1.2 Seismic design parameters. Risk Category (Standard Sec. 1.5.1) = IV Importance Factor, (Standard 1.5-2) = 1.5 Ie Table Long-period Transition Period, = 6 seconds TL Site Class (Standard Chapter 20) = C (per geotech) Design Spectral Acceleration Response Parameters = 0.824 SDS = 0.376 SD1 Seismic Force-resisting System (Standard Table 15.4-2) = Flat-bottom, mechanically anchored steel tank Response Modification Coefficient, = 3 R System Overstrength Factor, = 2 Ω0 Deflection Amplification Factor, = 2.5 Cd 17.6.1.3 Calculations for impulsive response. 17.6.1.3.1 Natural period for the first mode of vibration. AWWA D100 Section 13.5.1 does not require the computation of the natural period for the first mode of vibration. The impulsive acceleration is assumed to be equal to SDS. 17.6.1.3.2 Spectral acceleration. Based on AWWA D100 Section 13.5.1, the impulsive acceleration is set equal to SDS. = = 0.824 Sai SDS 17.6.1.3.3 Seismic (impulsive) weight. = 15.4 kips Wtank = (10 ft)2(10 ft)(0.0624 kip/ft3) (Wi/WT)= 196.0 (0.542) kips = 106.2 kips Wiwater The ratio (= 0.542) was determined from Equation 13-24 (only valid for 1.333) of AWWA Wi/WT D/H ≥ D100 for a diameter-to-liquid height ratio of 2.0 as shown below: = + = 15.4 + 106.2 = 121.6 kips Wi Wtank Wiwater 17.6.1.3.4 Base Shear.
17.6.1.2 Seismic design parameters. Risk Category (Standard Sec. 1.5.1) = IV Importance Factor, Ie (Standard Table 1.5-2) = 1.5 Long-period Transition Period, TL = 6 seconds Site Class (Standard Chapter 20) = C (per geotech) Design Spectral Acceleration Response Parameters SDS = 0.824 SD1 = 0.376 Seismic Force-resisting System (Standard Table 15.4-2) = Flat-bottom, mechanically anchored steel tank Response Modification Coefficient, R = 3 System Overstrength Factor, Ω0 = 2 Deflection Amplification Factor, Cd = 2.5 17.6.1.3 Calculations for impulsive response. 17.6.1.3.1 Natural period for the first mode of vibration. AWWA D100 Section 13.5.1 does not require the computation of the natural period for the first mode of vibration. The impulsive acceleration is assumed to be equal to SDS. 17.6.1.3.2 Spectral acceleration. Based on AWWA D100 Section 13.5.1, the impulsive acceleration is set equal to SDS. Sai = SDS = 0.824 17.6.1.3.3 Seismic (impulsive) weight. Wtank = 15.4 kips Wiwater = (10 ft)2(10 ft)(0.0624 kip/ft3) (Wi/WT)= 196.0 (0.542) kips = 106.2 kips The ratio Wi/WT (= 0.542) was determined from Equation 13-24 (only valid for D/H ≥ 1.333) of AWWA D100 for a diameter-to-liquid height ratio of 2.0 as shown below: Wi = Wtank + Wiwater = 15.4 + 106.2 = 121.6 kips 17.6.1.3.4 Base Shear.