مهندسی عمران شریف (Aug 2018)
بررسی آزمایشگاهی رفتار دیوار برشی کوپله با استفاده از بتن الیافی توانمند HPFRCC در تیر رابط با آرایش آرماتور گذاری متفاوت
Abstract
Coupling beam is as the first line of defense in the coupling shear walls and it acts as a shear fuse and is important to improve the seismic behavior of any structure. Coupling beams made of high performance fiber reinforced cementinous composite (HPFRCC) are capable alternatives compared to traditional concrete and result into increasing capacity and ductility and also reducing the congested amount of longitudinal and transverse and diagonal reinforcement. The design of coupling beams, with span-to-depth ratios that often range between 1.5 and 3.5, requires a special attention due to the large inelastic rotations and shear stress coupling beams can be subjected during a strong earthquake. In order to ensure adequate seismic performance, ACI Building Code (318-08) provisions for coupling beams in regions of high seismicity include the use of diagonal reinforcement designed to resist the entire shear demand, together with special column-type transverse reinforcement confining either the diagonal bars or the entire member.This paper investigates an experimental study on cyclic behavior of three concrete coupling beams with span to height ratio equal two. The first specimen with regular concrete was designed based on ACI 318-08 code including diagonal and spiral reinforcement, while the other specimens made with HPFRCC include, no spiral at the second specimen and no diagonal and spiral at the third specimen. Special instrumentation was used in the experimental specimens to measure the stain, displacement, and loads and rotations.The results showed that HPFRCC increased tensile capacity of concrete, prevented increasing the crack widths, increased absorbed energy and rigidity compared to plain concrete specimen; shear-tensile failure was changed to shear-slippage failure. Even though the spiral reinforcement was not used at the second HPFRCC specimen, the capacity and ductility were increased 20 and 37 percent respectively compared to the first specimen and casting the concrete was facilitated.
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