1 LESSLOSS Sub Project 7 Techniques and Methods for Vulnerability Reduction Seismic Upgrading of Structures Using Conventional Methods Lisbon 24 th May 07 LESSLOSS Dissemination Meeting Prof.Dr.M.Hasan Boduroğlu Assoc. Prof. Dr. Engin Orakdöğen Assist. Prof. Dr. Konuralp Girgin Berna Büyükşişli Civil Eng. MSc. Ergun Binbir Civil Eng. MSc. İstanbul Technical University

2 Existing Building-Normal Story Plan Strengthened Building-Normal Story Plan

3 Periods of the strengthened building Equivalent earthquake loads of strengthened building (TEC-2007) T x (sec) Strengthened building with fixed base 0.39 Strengthened building with mat foundation 0.47 Story No Total story weight (kN) Story mass (kNs 2 /m) Equivalent earthquake loads (kN) Ground Total

4 The mathematical model used for the analysis of building with mat foundation k s =30000 kN/m 3, q u =187.5 kN/m 2 Strengthened building with mat foundation EF=k s *A e *Unit Length Tension Limit=0 Compression Limit=q u * A e

5 Procedures for including soil-structure interaction effects according to FEMA-440

6 Procedures for including soil-structure interaction effects according to FEMA-440

7 Procedures for including soil-structure interaction effects according to FEMA-440

8 Procedures for including soil-structure interaction effects according to FEMA-440

9 Performance graphic of strengthened building with fixed base (FEMA-440)

10 Performance graphic of strengthened building with mat foundation and without kinematic interaction (FEMA-440)

11 Performance graphic of strengthened building with mat foundation including kinematic interaction (FEMA-440)

12 Performance graphic of strengthened building with mat foundation including kinematic interaction and base damping (FEMA-440)

13 Performance graphic of strengthened building with mat foundation including kinematic interaction and base damping(FEMA-440) Performance graphic of strengthened building with mat foundation including kinematic interaction and base damping (FEMA-440)

14 Comparison of the performance points of the strengthened building with fixed base and mat foundation (FEMA440) SaSa SdSd V (kN)D (m) Performance point of fixed base Performance point of mat foundation without kinematic interaction Performance point of mat foundation including kinematic interaction (    ) Performance points of mat foundation including kinematic interaction and base damping(    ) Performance points of mat foundation including kinematic interaction and base damping(    )

15 Performance evaluation of strengthened building with mat foundation according to non- linear static push-over analysis method of ATC- 40

16 PRELIMINARY CONCLUSIONS Kinematic interaction and base damping mostly depend on footprint area and effective stiffness of the structure. The elastic behavior of mat foundation does not affect the non-linear behavior of the structure and the top displacement of the structure with mat fondation is linearly translated compared to the structure with fixed base. Base shear demand of the structure with mat foundation is almost the same compared to the structure with fixed base due to the small post yield stiffness, however, displacement demand increases 33% depending on the increases of equivalent periodes. Increase of the base damping ratios do not considerably affect the base shear demands, but they decrease the displacement demands at the performance points. Soil pressures under the mat foundation remain at the linear region at the performance point levels.