Precast concrete double-tee connectors, part 2: Shear behavior

Seismic design of precast concrete diaphragms. a guide for practicing engineers

“…Experimental data have been generated on bent reinforcing bar hairpin connections (Venuti 1970;Kallros 1987;Naito et al 2009), welded plate connections (Pincheira et al 1998;Naito et al 2006;Cao and Naito 2007), angle plate connections (Spencer and Neille 1976), and a number of proprietary connections. Many of these connection test data sets are summarized in (Oliva 2000;Naito and Ren 2008;Cao and Naito 2009;Ren and Naito 2013).…”

Establishment of performance‐based seismic design factors for precast concrete floor diaphragms

“…The model is based on a planar diaphragm model developed for nonlinear static 'pushover' analysis [23], and extended for nonlinear time history analysis [12]. The properties used to construct the connector elements are provided by experimental data from extensive full-scale physical testing of individual diaphragm reinforcement [10,11]. The discrete modeling approach permits direct evaluation of local demands on the precast floor diaphragm.…”

“…The precast connector elements [see Figure 5(a)] in the discrete diaphragm model possess tensionshear coupling and nonlinear cycle-degrading effects (pinching, strength and stiffness degradation), as observed in the tests of isolated reinforcement [10,11]. Note this can be individual precast connectors or grouped topping reinforcement.…”

“…These design force levels are dependent on several design parameters related to building and diaphragm geometry, as well as lateral force-resisting system characteristics. In general, the diaphragm forces that meet the performance targets require an increase over current diaphragm design force levels [4], and are Research motivated by failures of precast diaphragms in past earthquakes [17] has indicated that: (i) diaphragm design forces may significantly underestimate the inertial forces that develop in the floor system during strong earthquakes [18] because of differences in the importance of higher modes during inelastic structural response [19]; (ii) non-ductile load paths may be present [20]; (iii) diaphragms possess complicated internal force paths [21] leading to combined tension-shear actions on individual diaphragm connectors [22]; (iv) inelastic demands can concentrate at certain key joints [23]; (v) current precast diaphragm reinforcement may not possess sufficient inelastic deformation capacity [10,11] for these demands; and, (vi) diaphragm flexibility can lead to excessive drifts of gravity system columns [24]. The new diaphragm design methodology [1,2,4,5] attempts to address these current shortcomings comprehensively.…”

New Precast Wall Connection Subjected to Rotational Loading

“…In addition to mechanical connectors, wet concrete is also used for joining them. Other types of connections used for floor and diaphragms have been investigated by researchers [13][14][15][16][17].…”