1

LESSLOSS Sub Project 7 LESSLOSS Sub Project 7 Techniques and MethodsTechniques and Methods for Vulnerability Reductionfor Vulnerability Reduction

Seismic Upgrading of Structures Using Conventional Methods

Lisbon 24th May 07 LESSLOSS Dissemination Meeting

Prof.Dr.M.Hasan BoduroğluProf.Dr.M.Hasan BoduroğluAssoc. Prof. Dr. Engin OrakdöğenAssoc. Prof. Dr. Engin OrakdöğenAssist. Prof. Dr. Konuralp GirginAssist. Prof. Dr. Konuralp GirginBerna Büyükşişli Civil Eng. MSc.Berna Büyükşişli Civil Eng. MSc.Ergun Binbir Civil Eng. MSc.Ergun Binbir Civil Eng. MSc.

İstanbul Technical University

2

Existing Building-Normal Story PlanExisting Building-Normal Story PlanStrengthened Building-Normal Story PlanStrengthened Building-Normal Story Plan

3

Periods of the strengthened buildingPeriods of the strengthened building

Equivalent earthquake loads of Equivalent earthquake loads of strengthened building (TEC-2007)strengthened building (TEC-2007)

Tx (sec)Strengthened building with

fixed base0.39

Strengthened buildingwith mat foundation

0.47

Story NoTotal story

weight(kN)

Story mass (kNs2/m)

Equivalent earthquake loads (kN)

4 448.20 45.60 194.20

3 878.10 89.50 312.20

2 878.10 89.50 236.80

1 878.10 89.50 161.50

Ground 881.60 90.00 86.20

Total 3964.10 404.1 990.90

4

The mathematical modelThe mathematical model used for the analysisused for the analysis of building with mat foundationof building with mat foundation

ks=30000 kN/m3,

qu=187.5 kN/m2

Strengthened building Strengthened building with mat foundationwith mat foundation

EF=ks*Ae*Unit LengthTension Limit=0Compression Limit=qu* Ae

5

Procedures for including soil-structureProcedures for including soil-structureinteraction effects according to FEMA-440interaction effects according to FEMA-440

6

Procedures for including soil-structureProcedures for including soil-structureinteraction effects according to FEMA-440interaction effects according to FEMA-440

7

Procedures for including soil-structureProcedures for including soil-structureinteraction effects according to FEMA-440interaction effects according to FEMA-440

8

Procedures for including soil-structureProcedures for including soil-structureinteraction effects according to FEMA-440interaction effects according to FEMA-440

9

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

10

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

11

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

12

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

13

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

14

Comparison of the performance points of Comparison of the performance points of the strengthened building with fixed base the strengthened building with fixed base and mat foundation (FEMA440)and mat foundation (FEMA440)

Sa Sd V (kN) D (m)

Performance point of fixed base 0.532 0.050 1657 0.076

Performance point of mat foundation without kinematic interaction

0.531 0.065 1682 0.107

Performance point of mat foundation including kinematic interaction ()

0.531 0.064 1675 0.096

Performance points of mat foundation including kinematic interaction and base damping()

0.528 0.052 1650 0.080

Performance points of mat foundation including kinematic interaction and base damping()

0.527 0.045 1629 0.069

15

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

16

PRELIMINARY PRELIMINARY CONCLUSIONSCONCLUSIONS

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.