Report - PEER - University of California, Berkeley

joint test specimens used in the current study fell within the ranges observed byMosier for joints designed prior to 1967, with two exceptions:• 5 of the 21 specimens included in this study have joint transversereinforcement. For these specimens, transverse steel ratios ranged from 0.2%to 0.4%. These volumes were considered to be sufficiently low, incomparison with the post-1967 average, to be representative of pre-1967construction.• 3 of 21 specimens included in this study had beam bottom reinforcement thatwas discontinuous through the joint. For these specimens, the bond indexwas higher than the maximum observed by Mosier (2000).Design yearTable 1. Design details for pre–1979 beam-column jointsVolumetric TransverseSteel Ratio (%)Shear Stress Demand/ f cBeam Bar Bond Indexµ = d f 2lave. min. max. ave. min. max. Ave. min. max.Pre-1967 0.0 0.0 0.2 0.21 0.09 0.30 21 12 381967-1979 0.9 0.0 2.1 0.15 0.06 0.29 23 14 43Note: In defining the bond index, µ, d b , is the diameter of the reinforcing bar, f y is the yieldstrength of the bar, l d is the anchorage length within the joint assumed to be equal to the columndepth, and f c is the concrete compressive strength and units are inches and pounds.Second, only laboratory test specimens with the same basic configuration andload history were used. All of the specimens represented sub-assemblages from twodimensionalbuilding frames and comprised the joint, the beams framing into the jointand extending to mid-span, and the columns framing into the joint and extending tomid-height. Lateral loading was applied as a shear force the top of the column andreacted by shear forces at the base of the column and beam ends. Lateral load wasapplied pseudo-statically using displacement control. In some cases, a constant axialload was applied at the top of the column to represent gravity load.Third, only test specimens for which sufficient data characterizing theprogression of damage in the beam-column joint were used. While all experimentalresearchers provide data characterizing the load-displacement response of laboratorytest specimens, the detail and consistency with which damage data are reported in theliterature varies substantially. In many cases, the lack of sufficient damage dataeliminated joint specimens for use in this study.2.2 Experimental Data Used in the StudyA review of the literature resulted in four test programs and twenty-one testspecimens that met the above criteria:• Meinheit and Jirsa (1977) investigated the impact of joint transversereinforcement on response. Data from one (MII) of the eleven specimensbydfc211