SEISMIC PERFORMANCE EVALUATION OF REGULAR AND IRREGULAR COMPOSITE MOMENT RESISTING FRAMES

Abstract

IN THIS STUDY, THE SEISMIC BEHAVIOR OF REGULAR AND IRREGULAR STEEL-CONCRETE COMPOSITE MOMENT-RESISTING FRAME (CMRF) BUILDINGS WAS INVESTIGATED. TO THIS AIM, 5, 8, 10, 13 AND 15-STORY CMRFS HAVING CONCRETE FILLED STEEL TUBE COLUMNS AND COMPOSITE BEAMS WERE DESIGNED AT HIGH DUCTILITY LEVEL AND THEIR PERFORMANCES WERE EVALUATED COMPARATIVELY. THE CASE STUDY CMRF STRUCTURES WERE CATEGORIZED INTO TWO GROUPS AS REGULAR AND IRREGULAR IN ELEVATION. EXAMINED IRREGULAR STRUCTURES HAVE SETBACKS IN DIFFERENT STORY LEVELS. THE SETBACK CONDITIONS CONFORM TO EUROCODE-8 SEISMIC DESIGN REQUIREMENTS. DURING THE DESIGN AND PERFORMANCE ANALYSIS, SISMOSTRUCT SOFTWARE WAS EMPLOYED. NONLINEAR STATIC PUSHOVER AND INCREMENTAL DYNAMIC ANALYSES WERE USED IN THE PERFORMANCE ASSESSMENT. THE UNIFORM AND TRIANGULAR LOAD DISTRIBUTIONS WERE USED IN THE PUSHOVER ANALYSIS WHILE A TOTAL OF 22 EARTHQUAKE ACCELERATION RECORDS WERE UTILIZED IN THE DYNAMIC ANALYSIS. THE VARIATION IN THE BEHAVIOR FACTORS, INHERENT STRENGTH FACTORS, OVERSTRENGTH FACTORS, DUCTILITY FACTORS, AND GLOBAL YIELD VALUES WERE EXAMINED FOR THE REGULAR AND IRREGULAR CMRF STRUCTURES. IT WAS OBSERVED THAT THE REGULAR CMRFS WERE MORE CONSISTENT WITH DESIGN ASSUMPTIONS AS COMPARED TO THE IRREGULAR ONES. MOREOVER, THE FORMER EXHIBITED MORE UNIFORM NON-ELASTIC DEMANDS OVER THE BUILDING HEIGHT ACCORDING TO THE RESULTS OF THE INCREMENTAL DYNAMIC ANALYSIS. UNDER THE SEISMIC SCENARIO ADOPTED, ALL THE BUILDING TYPES YIELDED HIGHER VALUES OF THE BEHAVIOR FACTOR COMPLIED WITH LIMITS AVAILABLE IN THE CODE