بررسي رفتارلرزه يي قاب هاي بتن مسلح مقاوم سازي شده با مصالح سيمكن

EVALUATION OF SEISMIC BEHAVIOR OF RETROFITTED REINFORCED CONCRETE FRAMES BY SIMCON MATERIAL

مصالح توانمند سيمكن، نوع جديدي از مصالح هستند كه به علت درصد بالاي الياف، مشخصات مكانيكي، همچون مقاومت خمشي، شكل پذيري، طاقت و كنترل عرض ترك آن ها به طور قابل توجهي بيشتر از بتن هاي اليافي متداول است و استفاده از آن ها، مشكلات اجرايي چنداني ندارد. در نوشتار حاضر، به منظور بررسي تاثير مقاوم سازي اتصال هاي تير - ستون با لايه هاي سيمكن در رفتار لرزه يي قاب هاي بتن مسلح، پس از صحت سنجي، 3 قاب بتني با تعداد طبقات 4، 7 و 10، ارزيابي و مقاوم سازي شده اند. نتايج به دست آمده از تحليل استاتيكي غيرخطي نشان داد كه مقاومت، شكل پذيري و تغييرمكان نهايي قاب هاي مقاوم سازي شده، افزايش قابل ملاحظه يي نسبت به قاب هاي كنترلي فاقد جزييات لرزه يي داشته است. همچنين مقاوم سازي اتصال هاي تير - ستون با لايه هاي سيمكن، سبب كاهش بيشينه ي دريفت طبقات و بيشينه ي جابه جايي بام و نيز افزايش بيشينه ي برش پايه ي قاب ها در تحليل تاريخچه ي زماني غيرخطي شده است.

SIMCON is a novel high performance material. This material has a high volume fraction of fiber, which has been mixed with mortar and aggregate. Structural behavior of this mixture induces strain hardening behavior under uniaxial tension. This behavior is the most important property of high performance material. Mechanical properties of this material, such as bending strength, ductility, toughness and crack width are more desirable than those of conventional fiber reinforced concrete. Moreover, using this material induces no constructional problem and can be used to repair, retrofit and construction of earthquake resistant buildings with high strength and ductility. In this research, with respect to advantage of SIMCON material, retrofitting of beam-column connection of RC frame with SIMCON material is evaluated. Verification is carried out comparing experimental and numerical model results for beam-column connection using OPENSEES software. Two specimens from an experimental study have been selected for verification. The hysteretic behavior of experimental and numerical results shows good agreement in the form of the maximum force and dissipated energy for the two specimens. Three 2D frames with 4, 7 and 10 stories have been developed for the study. These frames have non-seismic details in their joints. Effect of retrofitted joints in general behavior of retrofitted frames is evaluated and compared with non-retrofitted frames using nonlinear static (pushover) analysis. Results from pushover analysis show increase of lateral strength, ductility and ultimate displacement of the retrofitted frame compared to those of non-retrofitted frames. Evaluation of results shows that the ductility of retrofitted frames has been increased by 39% to 48% compared to similar non-retrofitted frames. Moreover, lateral strength for retrofitted frames has been increased by 50% to 57% compared to similar non-retrofitted frames. Assessment of nonlinear time history results obtained by applying seven earthquake records shows that the average maximum roof displacement for retrofitted frames has been decreased by 14% to 21% compared to the similar non-retrofitted frames. Furthermore, the average maximum base shear for retrofitted frames has been increased by 25% to 30% compared to similar non-retrofitted frames. The average maximum story drift ratio for retrofitted frames has been decreased by 42% to 47% compared to similar non-retrofitted frames.