Strengthening of hollow concrete masonry walls with or without opening using different techniques

الملخص EN

Egypt possesses a wealth of old unreinforced masonry (URM) buildings, most of them are of historic significance.

Many of these masonry structures need to be retrofitted either because of increasing loads and / or durability problems, change in seismic requirements, lack of maintenance and conversion of old buildings to new houses or occupancies.

In the last 25 years many achievements have been developed in the strengthening techniques and retrofitting of buildings.

The application of modern materials in strengthening and repairing techniques is now rapidly growing in many types of structures.

This paper presents an experimental study on retrofitting of the unreinforced concrete masonry walls by using some techniques which are grout injection, Ferro cement overlays, ordinary plastering and glass fiber polymers sheets (GFRP).

Eleven wall panels were subjected to uniform vertical loads.

Different parameters were taken into consideration during this study ; namely ; type of retrofitting techniques, the presence and absence of the wall openings and finally the shape of the opening.

Different properties were observed, measured and compared in this investigation ; such as crack pattern, failure mode, the cracking and failure loads, maximum strain, initial stiffness, and toughness.

In general ; the experimental results demonstrated that the using of these techniques of strengthening achieve better cracking behavior and mode of failure.

Also, the axial load capacity, initial stiffness and toughness of the wall were relatively enhanced.

It was found that the application of the grout injection greatly enhances the overall behavior of the wall panel.

The strength of the walls was directly affected by presence of the opening and its dimensions.

Many conclusions, relations, and recommendations that may be useful for designers were obtained and introduced.