Research on Application of Uplift-Restricted Slip-Permitted (URSP) Connectors in Steel-Concrete Composite Frames

Abstract

Tensile stresses and cracks in concrete slabs induced by a hogging moment have always been a disadvantage of steel-concrete composite structures and key issue of concern in the design of such structures. To reduce the tensile stress and control the crack width of the reinforced concrete (RC) slab, a new type of connector, called the uplift-restricted and slip-permitted (URSP) connector has been proposed and successfully applied in the area subjected to a negative bending moment in steel-concrete composite bridges. The feasibility of the URSP connector in steel-concrete composite frame buildings is investigated in this study based on a comprehensive parametric analysis. The effects of URSP connectors on the cracking behavior, as well as the stiffness and strength of composite frames, are systematically analyzed using an elaborate finite element model, which resembles a typical composite beam-column joint subjected to both lateral loads and vertical loads. In addition, an optimized arrangement length of URSP connectors is proposed for practical design. The research findings indicate that the application of URSP connectors greatly improves the crack resistance of RC slabs without an obvious reduction of the ultimate capacity and lateral stiffness of the composite frame. It is recommended that the distribution length of URSP connectors at each beam end should be 20–25% of the frame beam length.

Seismic Response Analysis of Steel–Concrete Composite Frame Structures with URSP Connectors

“…Furthermore, the modal characteristics of the bare steel beam were also calculated; compared with the results of the composite beams with various interface connections, the natural vibration period was greatly increased and the stiffness was greatly reduced. The relationship of stiffness obtained with this model was the same as those obtained with the local node analysis of the elaborate finite element model in [ 36 ] and the first-order natural vibration period obtained by the model established with Midas/gen 2015 software in [ 43 ]. Figure 6 shows the first three mode shapes of the full-span URSP connectors’ model, with modal properties of Y-translation, X-translation, and Z-rotation.…”

“…The constitutive relationships of steel and reinforcement were established considering the Bauschinger effect under hysteretic loads, and the constitutive relationship of concrete was established considering the degradation behavior under reciprocating loads, which can accurately simulate the mechanical properties of various materials under seismic loads. The constitutive relationships of the stud connector and the URSP connector are given in Figure 2 e,f, whose details were derived from [ 36 ]. Equations (1)–(4) describe the shear force–slip relationship curve of URSP connectors, which was proposed and validated by the authors’ research team [ 36 ].…”

“…The constitutive relationships of the stud connector and the URSP connector are given in Figure 2 e,f, whose details were derived from [ 36 ]. Equations (1)–(4) describe the shear force–slip relationship curve of URSP connectors, which was proposed and validated by the authors’ research team [ 36 ]. where V is the shear force; k 0 is the elastic stiffness before the interfacial bond is destroyed; δ and δ 0 are the interface slip and the slip when the interfacial bond is destroyed, respectively; δ u and δ f are the slips at maximum capacity and failure, respectively; t s is the foamed plastic thickness; A s is the screw area; d s is the screw diameter; V u is the ultimate shear capacity; E c and f c are the moduli of the elasticity and compressive strength of concrete, respectively; and f s is the yield strength of the screw.…”

“…The theoretical mechanism of partially releasing the composite effect of the steel–concrete composite beams by applying URSP connectors was explored [ 29 ], theoretical models of the uplift and slip performance of URSP connectors were studied [ 30 , 31 ], steel–concrete composite beams with URSP connectors were experimentally studied [ 32 ], and curved composite beams with URSP connectors were experimentally and numerically studied [ 33 ]. Except for composite beams, investigations of the application of the new type of connector have also included components of composite bridges [ 34 , 35 ], sub-assemblages, and connections of the composite frames of building engineering [ 36 , 37 , 38 ]. These studies and engineering applications [ 28 ] have proven that this novel composite structure with URSP connectors demonstrates good performance and a high crack resistance.…”

Emerging Construction Materials and Sustainable Infrastructure

“…In this special issue, four papers investigate the behaviours of novel prefabricated structures using experimental and numerical approaches [46][47][48][49]. On the other hand, several innovative structural forms are invented and the behaviours of those structures are presented and discussed in four other papers [50][51][52][53]. Two structural strengthening techniques using composite and shape memory alloy materials for the reinforced concrete structures are proposed and studied [54,55].…”