Caractérisation expérimentale de la résistance latérale des murs de brique traditionnelle pour l'analyse de la fragilité

Abstract

Damage surveys from worldwide past earthquakes have shown that unreinforced masonry (URM) structures are typically associated with the highest proportion of damage. In Eastern Canada, these structures are widely used as load-bearing or non-load-bearing walls in older residential, industrial or institutional buildings. Most of them are considered as pre-code buildings, as they were built prior to the introduction of seismic requirements in codes and standards. In order to improve the assessment of their lateral load resistance, an experimental project was carried out to investigate the mechanical parameters and the force-displacement capacity of traditional Unreinforced Brick Masonry (UBM). The objective of this research project is to characterize the behaviour of traditional UBM walls under cyclic loading to allow a better evaluation of their lateral resistance under seismic loads. The experimental program includes the characterization of the mechanical properties of the UBM and its constituents. It is composed of two phases of tests on UBM assembly samples and two-leaf UBM wallets. Assembly samples and wallets were built with manufactured moulded clay bricks typically used as replicas of traditional UBM, and cement-lime mortar used to match the mechanical properties of the original traditional cement-lime mortar. The first phase included a diagonal shear tests on six wallets (459 mm x 459 mm x 204 mm and 861 mm x 861 mm x 204 mm), as well as compressive and joint shear sliding tests on 18 and 54 UBM assembly samples respectively. The results from this phase were used to define the second phase, which consisted in carrying out quasi-static-cyclic tests on three wallets (861 mm x 660 mm x 204 mm) to capture the lateral nonlinear hysteresis behaviour of the UBM. The lateral force deformation behaviour of the wallets, under three different vertical loads, was used to develop bilinear capacity curves. The phase also included the compressive and joint shear sliding tests on 9 and 27 UBM assembly samples respectively. For a better characterization of the UBM, the assembly samples were made with mortar extracted from batches used to build the different wallets. Several properties were obtained form the tests. The diagonal shear tests gave an average diagonal tensile strength of 0,79 ± 0,03 MPa and an average shear modulus of 2,08 ± 0,17 GPa. The UBM samples tested in compression showed an average compressive strength of mortar, brick and UBM of 5,35 ± 1,0 MPa, 26,3 ± 4,8 MPa et 14,8 ± 2,1 MPa, respectively. The average elasticity modulus of brick and UBM was 3,6 ± 1,1 GPa and 3,18 ± 0,82 GPa, respectively. A coefficient of friction of 0,94 and a cohesion of 0,29 MPa were obtained from the shear tests on UBM samples. Mechanical properties of the UBM and the displacement capacity of the wallets were then used to calibrate models taken from the literature and a macro-element model of the wallets using the equivalent frame modelling method with the software 3-Muri©. Results of this study will contribute to a better evaluation of the lateral resistance and seismic performance of UBM buildings, thereby improving damage prediction for seismic risk studies and selection of efficient rehabilitation and strengthening strategies.

Date	9 Jan 2019
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Marie-José Nollet (Supervisor)