Extended Tension Chord Model for Boundary Elements of RC Walls Accounting for Anchorage Slip and Lap Splices Presence

Danilo Tarquini,João Pacheco De Almeida,Katrin Beyer

doi:10.1186/s40069-019-0381-9

Abstract

This paper presents a mechanical model for the simulation of reinforced concrete (RC) wall boundary elements with lap splices, which builds on the tension chord model. The model is composed of an assembly of components, each one accounting for a different source of deformation. Namely: (i) an anchorage-slip element accounting for the strain penetration of the longitudinal reinforcement into the foundation; (ii) a basic tension chord element evaluating the response outside the lap splice zone; and (iii) a lap splice element describing the behaviour within the lap splice region. For an imposed global displacement, the model provides the steel and concrete stress and strain distributions, the crack distribution and opening, as well as the global resisting axial force. For spliced members, the ultimate displacement is computed through a semi-empirical relationship providing the average lap splice strain at failure. Validation is carried out against a series of uniaxial cyclic tests on RC wall boundary elements featuring both continuous and spliced reinforcement; different lap splice lengths and confining reinforcement are considered. Overall, a good match is obtained between numerical and experimental results in terms of crack width, rebar strain distribution along the splices and ultimate displacement.

Highlights

Experimental tests on reinforced concrete (RC) walls have shown that the presence of lap splices may lead to a significant reduction of the member strength and ductility capacity (Almeida et al 2017)
The component presented in this subsection allows to account for the presence of lap splices in RC wall boundary elements and to estimate: (i) the steel strain distribution in the pair of spliced rebars; (ii) the crack width along the lapsplice length as well as the width contribution to the splice-end cracks originating from lap-splice deformation; (iii) the total lap-splice displacement and the failure point
The components described in the three previous subsections can be connected in series in order to simulate the response of RC wall boundary elements with lap splices subjected to increasing tensile loading

Summary

Introduction

Experimental tests on reinforced concrete (RC) walls have shown that the presence of lap splices may lead to a significant reduction of the member strength and ductility capacity (Almeida et al 2017). The present work proposes a mechanical model for the simulation of RC wall boundary elements with lap splices It represents an extension of the tension chord model (Marti et al 1998), reviewed, which adopts the fundamental hypothesis on the constitutive materials (steel and concrete) and bond–slip laws. The solution procedure, which concludes the same section, allows to obtain for an imposed global displacement: the steel and concrete stress and strain distributions along the boundary element, crack location and width, and the total applied axial force. The reduction of the steel tangent stiffness (from Es to Esh) and bond stress (from τb0 to τb1) causes the shift from linear to bilinear stress and strain distributions, as represented in state H of Fig. 3a

Mechanical Model for Boundary Elements of RC Walls with Lap Splices

Model implementation: iterative procedure and failure criteria

Findings

Conclusions