مقاله انگلیسی رایگان در مورد رفتار لرزه ای قاب های بتن مسلح صفحه ای با قاعده – اسپرینگر 2018

When large amounts of fibres are mixed in concrete, the resulting fiber reinforced concrete (FRC) material shows ductile behaviour both in compression and in tension, displaying tensile strain hardening or softening behaviour (Di Prisco et al. 2009). As a result, the use of fiber reinforced concrete significantly improves the structural performance of reinforced concrete (RC) members, not only under static and fatigue loading, but also under dynamic and earthquake loading. The presence of structural fibers in the concrete matrix enhances the ductility and dissipation properties of the material (Vasanelli et al. 2014; Yuan et al. 2013; Bayasi and Gebman 2002; Filiatrault et al. 1995; Henager 1977; Jiuru et al. 1992; Minelli and Plizzari 2013). Such properties make fiber reinforced concrete and high performance fiber reinforced concrete (HPFRC) highly damage-tolerant and especially suitable to be used in inelastic and joint regions, where high load bearing capacity and energy dissipation are required. The ability to absorb large inelastic deformations and to resist shear reversals during earthquake events is an additional important requirement fulfilled by FRC and HPFRC (Parra-Montesinos et al. 2005), whose improved tensile resistance and hardening increase structural shear strength, especially under multi-axial stresses. Mishra and Li (1995) found that mechanical properties of engineered cementitious composites (ECCs) in shear are similar to those in tension. Shannag et al. (2005) demonstrated that using steel FRC to replace conventional concrete in beam–column joints can significantly increase their seismic behaviour. In joint regions with weak shear reinforcement, the presence of HPFRCs can turn the failure mode from brittle (in shear) to ductile (Yuan et al. 2013). Similarly, a recent experimental campaign showed that using ECC in beam–column joints can significantly increase the seismic performance of lightly reinforced joints as well (Yuan et al. 2013). This finding was also proved by many researchers over the last decade (Li and Wang 2002; Fischer and Li 2002a, b, 2003). Hence, using FRC/HPFRC in the joint regions can be highly beneficial since it can (a) replace conventional concrete (always brittle in shear); (b) limit or avoid reinforcement congestion; and (c) improve the overall performance under sustained and cyclic loads. Several international design codes, including Eurocode 8 (2004) and the Italian Building Code (2008), referred to as NTC08 below, are well known for their rather conservative provisions concerning the items mentioned above, so that they often require an excessive amount of reinforcements, even in the design of low-ductility frames.