The Effect of CFRP Application on the Strength and Dynamic Characteristic of Unreinforced Masonry Wall

Abstract

This paper presents the results of experimental and analytical investigations of an unreinforced masonry wall (URM) exposed to continuous tensile-compressive cyclic loading. For the experimental investigation, a sample masonry wall (SMW) was designed inside a rectangular steel frame carried by pinned supports and built over a distance of 1200 mm in length by 1500 mm in height. The SMW was made of bricks whose dimensions were 285 mm × 185 mm × 130 mm. Under the influence of cyclic loading, damages appeared as diagonal or scattered cracks. The SMW was retrofitted by using carbon fiber-reinforced polymer (CFRP). An epoxy resin-based product and layers of CFRP were placed on the damaged SMW according to the crack patterns to acquire better recovery, effective strengthening, and enhanced performance. The retrofitted SMW underwent the same cyclic loading to obtain the effects of CFRP on the load–displacement capacity of the damaged masonry wall. Furthermore, an operational modal analysis test was conducted over SMW (the undamaged, the undamaged and retrofitted with CFRP) to determine their real dynamic characteristics. For analytical investigations, finite element analysis (FEA) was implemented in ABAQUS software with a simplified micro-modeling approach and damages were considered only in terms of displacement in this work. Nonlinear cyclic analysis was performed to obtain crack patterns and displacements. To determine modal parameters such as mode shapes and frequencies, modal analysis was also conducted. The obtained results such as displacements, damage patterns and modal parameters from analytical investigations were compared with experimental investigations. In the comparison of analytical and experimental studies, the results showed that the dynamic characteristics such as mode shapes and natural frequencies of SMW were changed. The use of CFRP increased up to 36% of the frequencies of the damaged sample wall. Furthermore, the shear strength capacity of SMW retrofitted by CFRP was significantly increase.