IABSE - IASS 2011 SYMPOSIUM

SEPTEMBER 2011 LONDON

EVALUATION OF SEISMIC DESIGN

METHODOLOGIES IN TURKEY

IABSE WG7 ANNUAL MEETING 19.09.2011

Dr. Mete Gercek Consulting Engineer , Turkey

mtgercek@uydunet.net 00 90 532 241 55 79 Member – Working Group 7 , IABSE

A ) 17 August 1999 Kocaeli and 12 November Düzce 1999 earthquakes have resulted in more than 18000 life losses. B) Destructive effects of these earthquakes resulted in upgrading of seismic design methodologies in Turkey.

Insufficient beam seat length , ArifiyeViaduct , 1999 Kocaeli Earthquake

Bolu Viaduct - Low design PGA and ignorance of near-fault (NF) effect AASHTO LRFD Bridge Seismic Design C 3.4.3.1 0,4 g Hysteretic dampers , Friction Pendulums

The viaduct had been designed assuming an effective ground acceleration (EGA) amounting to 0.4 g, in agreement with AASHTO recommendations in force at that time (edition 1989), such parameters relating to an earthquake with a return period of 475 years. The design seismic forces and displacements were determined by means of nonlinear time history analyses performed using seven uni-directional artificial accelerograms. The 5% damped acceleration spectra of the artificial accelerograms matched the AASHTO soil-type-II spectrum scaled to 0.4g peak ground acceleration.

Construction was almost completed before 1999 Earthquake.

Liquefaction Failure AASHTO C3.4.3 Soft Story Effect

Catastrophic results of 1999 earthquakes resulted in significant upgrading of the codes and design methodologies.

Performance based design and usage of energy dissipation devices increased rapidly.

National codes on perfromance based design of structures (improved) and design of seismically isolated structures have been published.

Near-fault effects and liquefaction are taken into account in recent structural designs.

Sakarya-2 Viaduct in Turkey Design Year:2008 (By courtesy of Limak Construction Co. Ankara) )

LRB Bearings after prototype testing ( by courtesy of ALGA SpA)

Sakarya 2 viaduct is located within 300 meters of the North Anatolian Fault and located on liquefiable soil. All these effects are taken into account in the design. (PGA1000= 0.9 g)

The viaduct has 9 spans with a maximum span length of 52 meters. The superstructure is a composite and continuous (R.C. slab& steel girders) system.

The bridge is seismically isolated by using a hybrid

seismic isolation system consisting of lead rubber bearings and elastomeric bearings. ( 4 elastomeric bearings + 2 LRBs at each pier).

The post-elastic period of the isolation system is kept relatively low (T2 < 2 sec.) in order to be able to keep away from strong long period components resulting from near-fault effect and liquefaction.

Near-Fault Effect ; Velocity pulse

Nonlinear analysis procedures for deformation-based seismic assessment: A new era in earthquake engineeriing The last decade of the previous millennium witnessed the development of the concept of performance-based seismic assessment, where seismic demand and consequent damage are estimated on a quantifiable basis under given levels of seismic action and such damage is then checked to satisfy the acceptable damage limits set for the specified performance objective(s). Since damage to be estimated at the component level is generally associated with the nonlinear behavior under strong ground motion, the concept of performance-based seismic assessment is directly related to nonlinear analysis procedures and deformation-based seismic assessment concept. Ref. NONLINEAR ANALYSIS PROCEDURES FOR SEISMIC ASSESSMENT AND DESIGN OF BRIDGES , Prof.Dr. M. NURAY AYDINOGLU

REFERENCES 1 - AASHTO, Guide Specifications for LRFD Bridge Seismic • Design , 2009. • 2 - EUCentre, Test Report for Algasism Bearings, 2009. • 3 - Yuksel Proje Uluslararası AS, Structural Calculations Report for • Sakarya-2 Viaduct . • 4 - Specification for Structures to be Built in Disaster Areas • PART III - EARTHQUAKE DISASTER PREVENTION • (Chapter 5 through Chapter 13) • Issued on: 2.9.1997, Official Gazette No.23098 • Effective from: 1.1.1998 • Amended on: 2.7.1998, Official Gazette No.23390 5 - Seismic Isolation Specification , Draft dtd. May 2008 , Turkish Association for Seismic Isolation • 6 – Performance of Seismic-Isolated Bridges in Relation to Near-Fault Ground- Motion and ısolater • Characteristics, Murat Dicleli • 7 – Engineering characterization of near fault ground motions, Paul g. Somerville

Thanks to Dr. Cenan Ozkaya-Yuksel Proje Uluslararası Co. for his contribution

Thanks for your attention

Dr. Mete Gercek Consulting Engineer , Turkey

mtgercek@uydunet.net 00 90 532 241 55 79 Member – Working Group 7 , IABSE