Core testing method to assess nonlinear shear-sliding behaviour of brick-mortar interfaces: A comparative experimental study

Jan G. Rots,Samira Jafari,Rita Esposito

doi:10.1016/j.conbuildmat.2020.118236

Jan G. Rots, Samira Jafari + Show 1 more

Open Access

https://doi.org/10.1016/j.conbuildmat.2020.118236

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Abstract

In this study, tests on cores and companion tests on triplets are compared with respect to the evaluation of the nonlinear shear-sliding behaviour of masonry, including the determination of post-peak softening response. Due to its slightly-destructive sampling nature and its good agreement with triplet results, the core testing method is confirmed to be a competitive technique for the in-situ assessment of the cohesion, friction coefficient, and shear modulus of mortar. Additionally, the comparisons in terms of dilatancy and energy dissipation, novel aspects with respect to previous studies, provide interesting insights for further research on the cohesive and frictional mechanisms occurring at brick-mortar interfaces.

Highlights

Nonlinear numerical analyses, often used for the assessment of unreinforced masonry (URM) buildings subject to earthquake and wind load, require a detailed description of nonlinear shearsliding behaviour along the brick-mortar interface, including the evaluation of post-cracking response
Through a comparative experimental approach, this study examined the suitability of shear tests on small-diameter cores to assess nonlinear shear-sliding behaviour along a brick-mortar interface
An experimental program was set-up at Delft University of Technology to compare the results obtained from shear tests on cores and from triplet tests on seven masonry objects

Summary

Introduction

Often used for the assessment of unreinforced masonry (URM) buildings subject to earthquake and wind load, require a detailed description of nonlinear shearsliding behaviour along the brick-mortar interface, including the evaluation of post-cracking response. The failure mode of the cores with mortar inclination angles between 40° and 55° was predominantly described as a shearsliding along the brick–mortar interface, enabling the calculation of the shear strength parameters in agreement with the Coulomb friction criterion [21,22,23,24] In this context, to confirm the accuracy of the failure criterion established by the core testing method, Mazzotti et al [22] and Pelà et al [23] performed shearcompression tests on companion specimens. Considerations of the energy dissipation and dilatancy effects in the core and the triplet tests provide valuable new insights that highlight the potential of the core testing method for the in-situ characterization of masonry

Experimental program

Testing objects

Testing procedure

Elaboration of experimental results

Global behaviour

Cohesion and friction coefficient

Elastic shear modulus of the mortar joint

Fracture energy for shear-sliding cracking

Dilatant behaviour

Findings

Conclusions