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MOHAMMAD KAZEM BAHRANI
AMIN NOORALIZADEH
NIMA USEFI
MAJID ZARGARAN

Abstract

GIVEN THE IMPORTANCE OF BRIDGE SERVICEABILITY AFTER SEVERE EARTHQUAKES, THE NEED FOR SEISMIC RETROFITTING OF THE EXISTING BRIDGES HAS BECOME CRITICAL IN RECENT YEARS. THE STUDY EXAMINED THE SEISMIC EVALUATION OF CONCRETE BENTS OF HIGHWAY BRIDGES DESIGNED AND IMPLEMENTED ACCORDING TO THE 1990S REGULATIONS. COMPARED WITH THE OLDER CODES, 1990S CODES HAVE MORE COMPLEX DETAILS FOR THE CONNECTION. HENCE, EXPERIMENTAL AND NUMERICAL STUDIES WERE UTILIZED AND THE NEED FOR RETROFITTING WAS EXAMINED IN THIS RESEARCH AS WELL. SIGNIFICANT IMPROVEMENT WAS OBSERVED IN THE BEHAVIOUR OF THE SPECIMENS DESIGNED WITH 1990S CODES. HOWEVER, THIS IMPROVEMENT IS NOT ENOUGH AS STRENGTH DEGRADATION WAS SEEN IN THE INNER CYCLES OF THE HYSTERESIS CURVES. THEREFORE, SEISMIC IMPROVEMENT WAS PERFORMED USING PERFORMANCE LEVELS. RESULTS SHOWED THAT IN THE CONNECTION REGION, THE LONGITUDINAL BAR SLIPPAGE OCCURS AND THE PERFORMANCE OF CONNECTION IS WEAK. A SPECIMEN WAS CONSTRUCTED WITH EXTERNAL PRE-STRESSING IN A TRANSVERSE DIRECTION FOR RETROFITTING. THE LEVEL OF IMPROVEMENT IN BEHAVIOUR WAS EVALUATED AS WELL USING PARAMETERS SUCH AS ENERGY DISSIPATION, PERFORMANCE LEVELS AND FORCE-DISPLACEMENT CURVES.

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