Cyclic In-Plane Shear of Concrete Masonry Walls Strengthened by FRP Laminates


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Title: Cyclic In-Plane Shear of Concrete Masonry Walls Strengthened by FRP Laminates

Author(s): M.A. Haroun, A.S. Mosallam, and K.H. Allam

Publication: Special Publication

Volume: 230


Appears on pages(s): 327-340

Keywords: FRP laminates; in-plane cyclic loads; masonry walls; retrofitand repair

Date: 10/1/2005

Cyclic in-plane shear tests were conducted on six full-scale walls built fromreinforced concrete masonry units and strengthened by unidirectional compositelaminates. Carbon/epoxy, E-glass/epoxy and pre-cured carbon/epoxy strips wereplaced on one or both sides of the walls. Each wall sample was loaded with a constantaxial load simulating the gravity load, and incremental cyclic lateral shear loads wereapplied in accordance with the Acceptance Criteria (AC-125) of the International CodeCouncil Evaluation Services (ICC-ES 2003). Displacements, strains and loads werecontinuously monitored and recorded during all tests. Evaluations of the observedstrength and ductility enhancements of the strengthened wall samples are made andlimitations of such retrofit methods are highlighted for design purposes.Results obtained from current tests indicated that the limit-state parameter influencingstrength gain of the FRP retrofitted walls was the weak compressive strength of themasonry units, especially at the wall toe where high compression stresses exist.Despite such a premature failure caused by localized compression damage of themasonry at the wall toe, notable improvement in their behavior was achieved byapplying the FRP laminates to either one or two sides of the walls. However, it shouldbe cautioned that available theoretical models may significantly overestimate the shearenhancement in the FRP strengthened walls, if other limiting failure modes are notconsidered.