1

EARTHQUAKE ENGINEERING

Design Response Spectrum

1940 El Centro, 0.35 g, N-S

2

5% Damped Spectra for Four California Earthquakes scaled to 0.4 g (PGA)

Smoothed Elastic Response Spectra Newmark-Hall Spectra

3

CONSTRUCTION OF ELASTIC DESIGN SPECTRUM USING NEWMARK HALL APPROACH

Tripartite Plots

4

AMPLIFICATION FACTORS: ELASTIC DESIGN SPECTRA (Dynamics of Structures-Chopra)

5

EXAMPLE: (DYNAMICS OF STRUCTURES-CHOPRA-PAGE 222)

6

7

8

9

COMPARISON OF DESIGN AND RESPONSE SPECTRA

10

11

CODE-BASED DESIGN SPECTRUM

o o o o o o o

12

IBC 2018, ASCE 7-16 DESIGN SPECTRUM

13

14

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.

16

17

18

IRAQI SEISMIC CODE (ISC-2017) DESIGN RESPONSE SPECTRUM

19

20

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.

21

7. The design response spectrum curve shall be developed as indicated in Fig.

below.

22

BSs

[2]

23

B1S

[2]

24

25

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

27

oTaS

oTsT

aSD1S

sTaS

Baghdad ISC-2017 Spectrum

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

29