In-Plane Strengthening of URM Infill Wall Assemblages Using GFRP Laminates

Wael El-Dakhalchni; Ahmad Hamid; Mohamed Elgaaly

Masonry buildings, many of which are of considerable historic and architectural importance, constitute a significant portion of the building stock in North America and throughout the world. Many of these buildings have suffered from the accumulated effects of inadequate construction techniques and materials, overloading, foundation settlement, and environmental deterioration, and are structurally deficient or marginal for current use. In addition to these factors, changed usage and more stringent seismic design requirements have resulted in many masonry structures in need of retrofitting and upgrading through strengthening. While there are several types of masonry structural elements within a building, the most important elements that are subjected to earthquake damage are the bearing walls which are designed to resist primarily gravity and wind loads with little to no consideration of the forces generated by a seismic event. A strong earthquake introduces severe in-plane and out-of-plane forces to the URM walls which may lead to catastrophic collapse. Infill walls are another type of masonry elements that are extensively used in old and new frame buildings. Although considered non-structural elements, yet under seismic action, they tend to interact with the surrounding frame and may result in different undesirable failure modes both to the frame and to the infill wall [El-Dakhakhni et al. (2001)]. In general, URM structures have a poor performance record even in moderate earthquakes. Their behavior is usually brittle with little or no ductility and both structural and non-structural parts suffer various types of damages ranging from invisible cracking to crushing and eventually disintegration. This behavior constitutes a major source of hazard during seismic events and can create a major seismic performance problem facing earthquake engineers today. Some methods of seismic upgrading such as the addition of new structural frames or shear walls, have been proven to be impractical, they have been either too costly or restricted in use to certain types of structures. Other strengthening methods such as grout injection, insertion of reinforcing steel, prestressing, jacketing, and different surface treatments were summarized by Hamid et al. (1994). Each of these methods involves the use of skilled labor and disrupts the normal function of the building. The use of FRPs as retrofitting and strengthening materials is a valid alternative because of their small thickness, high strength-to-weight ratio, high stiffness, and ease of application. Recent researches [Triantafillou (1998), Myers (2000), and Velazquez-Dimas et al. (2000)] have shown that a relatively thin layer of FRP laminates adhered to the wall surface has excellent properties as an out-of-plane retrofitting method. The work presented herein investigates the effects of applying GFRP laminates on the in-plane behavior of URM assemblages subjected to different stress conditions present in infill walls. One of the objectives of the presented experimental work is to investigate the effects of different GFRP laminates on the strength, failure modes as well as the post peak strength of assemblages compressed in the two orthogonal directions. Another objective is to demonstrate that, with the proper selection of the GFRP laminate, shear failure, which is a common failure mode in URM shear and infill walls, can be eliminated. This rather brittle failure mode is usually attributed to the low shear strength of URM walls or to the inadequate shear reinforcement in reinforced walls.

In-Plane Strengthening of URM Infill Wall Assemblages Using GFRP Laminates

Additional Links

Abstract

Metrics

Details

In-Plane Strengthening of URM Infill Wall Assemblages Using GFRP Laminates

Additional Links

Abstract

Metrics

Details

Drexel University Social media