Precast concrete double-tee connections, part 1: Tension behavior

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

“…A factor of safety of 1.5 is applied to the qualification deformation δ q to determine the allowable deformation δ a . The HD allowable deformation δ HD a = 10 mm was established relative to δ HD q , the maximum deformation capacity of the best performing reinforcement details, identified as 15 mm in the testing [10]. The MD allowable deformation δ (MD qualification deformation) of 7.5 mm, based on a wide range of diaphragm reinforcement tests [10].…”

“…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.…”

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

“…Experiments were conducted using a variety of subassemblies that do not necessarily conform to the qualification requirements of Section 8 of this Guide. 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).…”

Experimental Study on an Optimized-Section Precast Slab with Structural Aesthetics

“…In the half PC method, the external loads in the construction stage should be resisted by the PC members only; otherwise, it requires supporting posts which is costly and therefore reduces a huge advantage of PC construction methods. Many alternatives have thus been developed to enhance the load carrying capacity of PC slab members at the construction stage [7][8][9][10] and PC slabs with vertical ribs, such as a modified double tee slab (DTS) and a multi-ribbed slab (MRS), are some examples [11][12][13][14][15]. In addition, many efforts have been made to develop slender half PC members with a long span-to-height ratio (l/h) to maximize space utilization while ensuring efficient structural resistance performance.…”