Masonry Confinement Using Steel Strips
This paper presents the behavior of masonry columns confined with steel strips for increasing the axial capacity and stress-strain relationship. The test specimens are divided into three groups; each consists of three specimens with the variables: amount of reinforcement and cross-section aspect ratio. The cross-sectional aspect ratio of the three groups were 1, 2, 3 respectively. The experimental data and highlights different aspects of confinement. The steel strips enhance the ultimate stress and strain but this increase in strength is dependant on the cross-sectional aspect ratio. It is also concluded that the increase in load-carrying capacity and the deformability of masonry is significantly enhanced due to confinement using steel strips and the increase is linear to the average confining stress. The confinement of masonry with steel strips is quite viable and cheap option for strengthening
Strengthening of fair face masonry columns with steel hooping
The innovative technique here illustrated is the result of historical evolution of ancient systems of hooping and is conditioned by design criteria that take into account the structural life in the respect of existing elements. It consists in the application of small diameter stainless steel cords able to provide overlapping hoops at every course over the entire height of the column. Three series of uniaxial compression tests, with a total of 19 specimens, were conducted on model brick masonry columns with these variables: cross-section geometry, amount and scheme of confining reinforcement. Laboratory outcomes have shown how the investigated confining systems are able to provide significant gains in terms of compressive strength (values of the confined-to-unconfined strength ratio ranging between 1.45 and 3.00 have been obtained). Test results have been finally used to assess the reliability of the existing design equations suggested by Italian National Research Council for design of FRP strengthening of masonry columns.
Field Evaluation of Unreinforced Masonry Walls Strengthened with FRP Composites Subjected to Out-of-Plane Loading
Unreinforced masonry (URM) walls at a decommissioned building in St. Louis, Missouri were tested to failure. The walls belonging to the present experimental program were subjected to out-of-plane loading. Previous work on URM and reinforced masonry walls strengthened with FRP laminates has shown remarkable increases in capacity and ductility. However, most of this research has been conducted under laboratory conditions, where, many times, it is a difficult task to represent real field conditions. In this context, this experimental program offered a singular opportunity for performing field experimentation on URM walls strengthened with Glass, Aramid and Carbon Fiber Reinforced Polymers (GFRP, AFRP and CFRP, respectively), as well as Glass Near Surface Mounted Rods. Parameters such as the type of composite system, strip width, and FRP installation methods were evaluated. A mechanism of failure caused by a shear-compression effect lead to the fracture of either the upper or lower boundary masonry units. Due to this failure mode, the walls were not able to develop a higher capacity compared to the control specimen.