Masonry Research for Limit-States Design.

Abstract : An experimental research program was conducted to determine certain critical material and design parameters of reinforced masonry necessary for the formulation of a new limit-states design standard. The research was divided into three subprograms: lap-splices, tension-stiffening, and biaxial compression-tension behavior. Tests were conducted to investigate lap splices in reinforced masonry, focusing on parameters which affect the strength and ductility of lap splices in both concrete and clay masonry construction. A performance criteria of 125 percent of the yield load of the reinforcement was adopted and used to establish critical lap lengths and maximum bar sizes. Tension-stiffening tests were conducted to develop data on the tensile behavior of reinforced masonry, especially in the postcracked state. The results of these experiments permined the quantitative expression of tension-stiffening behavior in both the pre- and postyield range. Tests were conducted to determine the biaxial compressive-tensile behavior of reinforced concrete masonry panels. The tests were conducted in a unique load frame which permifled independent control of lateral tensile and vertical compressive loads. A model describing the influence of lateral tensile strain on the compressive stress and strain at compressive failure was obtained.