Monotonic and cyclic performance of threaded reinforcement splices

Abstract

This paper examines the fundamental uniaxial monotonic and cyclic response of reinforcement bars connected with threaded mechanical couplers. Based on a survey of available splicing forms, two types of threaded couplers with different geometric configurations, namely 'parallel threaded couplers' and 'parallel threaded sleeve couplers' are selected for detailed assessment. An experimental study consisting of twenty-four bare (in-air) and embedded (in-concrete) specimens incorporating threaded couplers and non-spliced counterparts, is described. The results enable direct assessment of strength as well as complete deformation characteristics, including the post-cracking and post-yield response, for both monotonic and cyclic conditions. After describing the material properties and specimen details, the main observations are reported based on detailed measurements of crack kinematics including crack width and spacing through a digital image correlation system. Complementary numerical studies, undertaken using nonlinear finite element procedures which are validated against the tests, enabled supplementary parametric investigations accounting for wider ranges of coupler geometries. The findings show that existing guidelines may be used for assessing the crack width and spacing, by accounting for the characteristic bond behaviour at the rebar and coupler regions. The complete deformational response may be obtained by using a suggested stiffness reduction factor that depends on the coupler geometry. Several 'in-air' performance parameters may also be used as a basis for the selection and implementation of couplers in applications requiring ductile member behaviour. , 16 (2018), 358-372. Structures

Inelastic cyclic behaviour of RC members incorporating threaded reinforcement couplers

“…Besides the steel material tests carried out on reinforcement samples from the beam-column members, 12 uniaxial tests, selected from a wider experimental programme covering rebars and couplers of different diameters and sizes [23,24], are reported herein. These selected uniaxial tests include 6…”

Elevated temperature characteristics of steel reinforcement incorporating threaded mechanical couplers

“…The intrinsic characteristics of the mechanical splices with compact couplers, that have an enlarged rebar cross-section near the threads due to the manufacturing process, and show minimal stresses recorded at the coupler region. On the other hand, for slender couplers, some strain localisation may occur at the threads as well as at the coupler-to-rebar interface, which can subsequently promote a failure at the coupler region in some cases [19].…”

“…Typically, parallel-threaded coupling systems have superior connection characteristics, working effectively both in tension and compression [19], with splices of relatively compact form exhibiting favourable ductility properties within concrete members [20,21].…”

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

“…To avoid previously mentioned mesh-dependency problems the crack band model with constant facture energy in which the tensile response is a function of the characteristic element length, may be considered. Models employing such approaches were able to predict the ultimate strength and deformational response of plain and reinforced concrete members (e.g., localized behavior under direct shear and tension [58,59], assessment of a long-term behavior [60], RC flat slabs with and without shear reinforcement under static loading [61][62][63], RC hybrid beams in shear and flexure [64][65][66][67]). However, detailed numerical studies on flat slabs with shear-heads are relatively limited and have typically focused on hybrid connections between steel columns and RC floors.…”