Wall bearing masonry is the structural system of a considerable portion of residential buildings worldwide. Occasionally it is required to make window or door openings in the loaded walls, which presents a threat to the building safety unless strengthening of the wall is performed before making the required opening. This paper presents testing, numerical modeling and nonlinear analysis of several external strengthening schemes performed on vertically loaded masonry walls prior to making openings in the walls. An experimental
program was conducted where eighteen unreinforced brick masonry walls with dimensions of 1200x1200x110mm are loaded by service
load, twelve of the walls are strengthened by different materials and schemes, the openings is made, then the vertical load on the wall is increased until failure. The strengthening schemes are made in the loaded wall surrounding the intended opening using fiber reinforced
polymer sheets and strips, steel reinforcement bars and ferro-cement layer. The obtained experimental results demonstrate the efficiency of the strengthening methods in compensating the reduction of wall capacity due to opening. Numerical modeling of the tested walls by
finite elements and nonlinear analysis are carried out using commercial software. Agreement between numerical and experimental results
demonstrates the efficiency of the numerical approach. Application is made on an actual case where a door opening was required to be made in a wall in the ground floor of an old building. Numerical modeling and nonlinear analysis are made to design strengthening and
study its efficiency in preserving the wall carrying capacity. The obtained results illustrate the applicability of the proposed approach as a
practical and valid tool for design of strengthening measures for the frequent requirement of making openings in existing load-bearing masonry walls while subjected to service loads. |
