( 2005), the first confinement option is practically difficult to construct when the average shear stress in the beam is greater than \( 0.5\sqrt \) MPa. This confinement method entails a very intricate arrangement of reinforcement, especially at the mid-span of the beam where opposite diagonal reinforcement groups meet each other. In the first option, each group of diagonal reinforcement comprises at least four longitudinal bars enclosed by densely spaced transverse reinforcement (Fig. 2013).īased on the previous studies mentioned above, section 18.10.7 in ACI 318-14 (ACI 2014) specifies two confinement options for coupling beams with diagonal reinforcement (Fig. 1996 Galano and Vignoli 2000 Harries et al. Diagonally reinforced coupling beams strongly resist sliding and have ductility, energy dissipation, and stiffness retention capacities superior to those conventionally reinforced coupling beams (Paulay and Binney 1974 Barney et al. Historically, Paulay and Binney ( 1974) first developed diagonal reinforcement for coupling beams. Many studies have been conducted with the aim of resolving this problem. Transverse reinforcement is not capable of preventing sliding shear failure when flexural cracks propagate across the entire depth of the beam between stirrups (Paulay and Priestley 1992). Therefore, coupling beams should be equipped with adequate reinforcement details that perform well during seismic events, providing adequate ductility and energy dissipation, as well as strength and stiffness (Paulay and Priestley 1992 MacGregor and Wight 2009).Ĭoupling beams reinforced by means of a conventional detail, with longitudinal bars parallel to the span of the beam, may experience sliding shear failure near the beam ends at which flexural cracks caused by reversed cyclic loading come across one another (Paulay 1971). When subjected to design-level earthquakes, coupling beams designed according to current design codes (NZS 1) are expected to suffer substantial inelastic deformations and to dissipate significant amount of energy (MacGregor and Wight 2009) they play a key role in the seismic performance of the entire coupled wall system. The test results revealed that HPFRCC coupling beams with bundled diagonal bars and widely spaced transverse reinforcement (one-half the amount of reinforcement required by current seismic codes) exhibited excellent seismic performance compared with ordinary concrete coupling beams having code-required distributed diagonal reinforcement and transverse reinforcement.Ĭoupled wall systems consisting of separate shear walls linked together by coupling beams at floor levels are effective in resisting wind- and earthquake-induced forces in high-rise buildings (Paulay and Priestley 1992). Four coupling beam specimens with length-to-depth aspect ratios of 2.0 or 3.5 were fabricated and tested under cyclic lateral displacements. The objective of this study was to develop simple reinforcement details for diagonally reinforced coupling beams reducing transverse steel by use of high-performance fiber-reinforced cementitious composites (HPFRCCs) and bundling diagonal bars are explored. However, it is difficult to construct coupled shear walls particularly because current design codes require complex reinforcing details within coupling beams. Coupled shear walls are efficient in resisting lateral forces induced by winds and earthquakes.
0 kommentar(er)
