Maw-Shyong Sheu Dept. of Architecture National Cheng-Kung Univ. Tainan, Taiwan

1. Seismic Assessment and Its Verification of Damaged Low-rise RC Buildings in Taiwan Chi-chi Earthquake Maw-Shyong Sheu Dept. of Architecture National Cheng-Kung Univ. Tainan, Taiwan

2. BACKGROUND • After the Taiwan Chi-Chi Earthquake, 1999, 60% of the damaged buildings were low-rise RC street buildings and RC school buildings.

5. OBJECTIVES • To propose a fast seismic assessment method for low-rise RC buildings w/o shear walls. • To verify the results of the proposed fast seismic assessment method by the collapsed, seriously damaged and moderately damaged RC buildings in the disaster area of the Chi-Chi EQK, 1999.

6. ASSUMPTIONS FOR THE FAST SEISMIC ASSESSMENT METHOD • Low-rise RC buildings with fundamental period less than 0.7 seconds. • Failed in strong beam weak column mode. • Calculated story by story independently. WALL

7. PROCESS OF CALCULATION • Plot static Q-Δ curve for every vertical member in shear-building deflection mode RC ColumnRC WallBrick Wall Q Q Q H H H Δ Δ Δ W W

8. PROCESS OF CALCULATION (cont’d) • Plot static push-over curve for the whole structure by superposing Q-Δ curve of each vertical member. • Plot equivalent bi-linear Q-Δ curve. Obtain inelastic Qu. • Calculate elastic response force, Qe. • Let Qe= EPA(C)(W). Obtain EPA. • Fu= Qe/Qu

9. Q (Du , Qu) (Dy , Qy) (Df , Qf) (Dc , Qc) D Q-D CURVE OF RC COLUMN flexural-shear interaction are considered for Qu

10. Q-D CURVE OF RC WALL Q (Du , Qu) logarithmic curve (Dc , Qc) D

11. Q-D CURVE OF RC WALL (cont’d) • For flexural behavior, RC wall is considered as a column with big cross-section. • Mcr ; Mu • ; • ;

12. Q-D CURVE OF RC WALL (cont’d) • Qsu = Qsc + Qss • For ultimate shear capacity contributed by rebars, Qss , consider the shear friction across a rational crack path at ultimate state. Qsu Qsu 45º 45º high-rise wall low-rise wall

13. Q-D CURVE OF RC WALL (cont’d) where and

14. Q-D CURVE OF BRICK WALL Du by plate theory; Qu by rational crack path Q (Du , Qu) polynomial curve D

15. CRACK PATHS OF BRICK WALLS TAKEN FROM ACTUAL DAMAGED STRUCUTRES

16. IDEALIZED CRACK PATHS OF BRICK WALLS AT ULTIMATE STATE tan q>H/W tan q <H/W with opening

17. ULTIMATE MATERIALS’ STRENGTHS FROM EXPERIMENTAL TEST sn tf fmbt fbt

18. ULTIMATE CAPACITY OF BRICK WALL

19. ULTIMATE DEFLECTION OF BRICK WALL where

20. VERIFICATION OF THE RPOPOSED ASSESSMENT METHOD [Example 1] Single street building at Tong-Su Town collapsed after the Chi-Chi Earthquake at actual EPA=0.48g.

21. EXAMPLE 1

22. SEISMIC PERFORMANCE DIAGRAM OF 2ND STORY

23. SUGGESTED MAX STORY DRIFT FOR PERFOEMANCE BASED STRUCTURE DESIGN ● General Building ▲ Important Building ■ Very important Building

24. [ EXAMPLE 2] Row street building at In-Lin County moderately damaged after the Chi-Chi Earthquake at actual EPA=0.27g. corridor

25. SEISMIC PERFORMANCE DIAGRAM OF GROUND STORY

26. CONCLUSIONS • The ultimate shear capacity of brick wall and RC wall may be calculated by the crack path concept proposed in this paper. • After verification of some damaged buildings in the disaster area of the Chi-Chi Earthquake, the proposed fast seismic assessment method is feasible for low-rise RC building structures.

27. CONCLUSIONS (cont’d) • The proposed fast seismic assessment method may be used to provide a complete seismic performance diagram for low-rise RC buildings w/o shear wall. • Once verification with some more damaged street buildings is finished, a simple chart for quick check of collapse EPA will be provided.

28. Thank you for your attention.