Caractérisation des propriétés mécaniques des bâtiments en maçonnerie non armée pour l'évaluation du risque sismique

Abstract

Unreinforced masonry (URM) buildings are considered among the most vulnerable to earthquakes. The lack of information on mechanical properties of stone URM buildings in Eastern Canada makes reliable seismic evaluation even more difficult. North American standards for testing masonry are primarily intended for the design of brick masonry structures. The characterisation of mechanical properties of stone URM must therefore be based on European standards and experimental researches. This research is focused on the characterisation of stone masonry components, limestone units and cement – lime mortar, small masonry specimens and one leaf masonry wallets. The stone selected for the experimental programme was St-Marc limestone. A cement – lime mortar was used with 1:2:8 ratios for cement, lime and sand, respectively. Compressive strength tests were carried out on stone units and on mortar samples taken from the mortar batch used during the construction of the URM specimen for the first phase of the experimental programme. The average stone and mortar compressive strengths were 101 ± 13 MPa and 3,3 ± 0,2 MPa, respectively. The mechanical properties of URM small specimens made of two or three stone units were established. The average compressive strength was 33,2 ± 3,2 MPa and corresponding elastic modulus 2 823 ± 186 MPa. The joint shear sliding strength tests lead to a cohesion and friction coefficient equal to 0,56 MPa and 0,85, respectively. The flexural bond strength of the horizontal joint was 0,23 ± 0,03 MPa. Finally, the last phase of the experimental programme consisted in evaluating the diagonal tension strength of one-leaf stone masonry wallets. The average mortar compressive strength for the wallets was 8,0 ± 0,9 MPa. The results gave a diagonal strength of 0,41 ± 0,08 MPa and corresponding shear modulus of 487 ± 10 MPa. The results of the compressive and diagonal tension tests were used to generate the capacity curve for a prototype stone URM building of two stories typical of the Old-Quebec and Old-Montreal region. This capacity curve based on experimental data was then compared to capacity curves obtained from literature data to promote the importance of the mechanical properties of URM to derive reliable models to base our assessment and define rehabilitation strategies. Considering the interest of seismic assessment of existing URM buildings, recommendations are made to improve knowledge on mechanical properties of stone URM buildings of Eastern Canada.

Date	21 Nov 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Marie-José Nollet (Supervisor)