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<br /> <br /> <br /> <br /> <br /> <br />3rd & Broadway, Santa Ana, CA <br />Volume 2 - Structural Calculations June 17, 2024 | Project # S21043.00 <br /> pg. 76 <br />4.8 ETABS RESULTS: SUMMARY OF COUPLING BEAM SHEAR STRESSES (FOR REFERENCE <br />ONLY) <br /> <br />4.8.1 DESIGN PROCEDURE <br />The reinforcement of the core wall coupling beams (link beams) is designed for the shear and moment <br />demands determined by the envelope of load combinations (which include DBE-level response spectrum <br />earthquake actions). The design of each coupling beam is performed using a spreadsheet which pulls <br />data from the ETABS analysis model and then designs each individual link beam section. <br />The reinforcement type of each link beam (conventional or diagonal) is determined according to the <br />requirements of ACI 318-14, 18.10.7 <br /> <br />Conventionally Reinforced Link Beams <br />As part of the lateral force resisting system, conventionally reinforced link beams follow the specifications <br />for coupling beams and special moment frame beams. They are checked to satisfy the ACI 318 -14 <br />requirements for: minimum & maximum longitudinal reinforcement ratio, minimum shear reinforcement, <br />shear reinforcement spacing, and maximum nominal shear strength of 18.6. <br />Longitudinal reinforcement is placed such that <br />ΦMn ≥ Mu. It is ΦMn= ΦAsfy0.9d, <br />where Φ=0.90 (tension-controlled sections), fy=60ksi, and 0.9d is considered the moment arm of section <br />forces. Shear reinforcement design satisfies <br /> ΦVn ≥ Vu. It is ΦVn = ΦAsfyd/s, and Vu=max(Vu, Vcap), <br /> <br />where Φ=0.75 (shear), s is the longitudinal spacing of hoops, Vu is the acting shear force from ETABS <br />analysis, and Vcap is the capacity design shear obtained assuming probable moments of opposite signs <br />being developed at the beam ends, thus Vcap=(2/L)(1.25fyAs)(0.9d), where L is the beam length. <br /> <br />