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5% Damped Spectra for Four California Earthquakes scaled to 0.4 g (PGA)
Smoothed Elastic Response Spectra Newmark-Hall Spectra
15
Design Spectrum Procedure
(ASCE-7-16, CHAPTER 11, SEISMIC DESIGN CRITERIA)
1. Determine basic ground motion parameters (Ss, S1) Zonation map.
2. Determine site classification (A F) Table 20.3-1 (ASCE-7-16).
3. Determine site coefficient adjustment factors (Fa, Fv) Tables 11.14-1&
Tables 11.14-2.
4. The Risk-Targeted Maximum Considered Earthquake (MCER) spectral
response acceleration parameters for short periods (SMS) and at 1 s (SM1),
adjusted for site class effects.
5. Determine design ground motion parameters (SDS, SD1)
6.
7. The design response spectrum curve shall be developed as indicated in Fig.
11.4-1.
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DESIGN SPECTRUM PROCEDURE
(ISC-2017, CHAPTER 2, SEISMIC DESIGN CRITERIA)
1. Determine basic ground motion parameters (Ss, S1) Zonation map of
Iraq,(ISC-2017,Chapter 2).
2. Determine site classification (A F),(ISC-Chapter 7).
3. Determine site coefficient adjustment factors (Fa, Fv) ,(ISC-Chapter 2).
4. The Risk-Targeted Maximum Considered Earthquake (MCER) spectral
response acceleration parameters for short periods (SMS) and at 1 s (SM1),
adjusted for site class effects,(ISC-2017,Chapter 2).
5. Determine design ground motion parameters (SDS, SD1) ,(ISC-2017,Chapter
2).
6.
26
EXAMPLE Utilizing the ISC-2017 code, determine design response spectra for Baghdad. Note: Assume stiff soil site class
30. =sS
10. =1S
D
Fa
Fa= 1.56
Fv
1 1S2.4 Fv=
1SSSM1SMSS
( )
( )
DSSD1S
28
Tutorial Problems-7 ------------------------------------------------------------------Due Date 23/4/2020 For the design earthquake at a site, the peak values of ground acceleration, velocity, and displacement have been estimated: 0.5g, 60 cm/sec , and 50 cm. For systems with 2% damping ratio, construct the 50th and 84.1th percentile design spectra.
a) Plot both spectra, together, on four-way log paper. b) Plot the 84.1th percentile spectrum for pseudo-acceleration on log-log paper, and
determine the equations for A (Tn) for each branch of the spectrum and the period values at the intersections of the branches.
c) Plot the spectrum of part (b) on a linear-linear graph (the Tn scale should cover the range 0 to 5 sec).
13/06/2021