Flexural Strengthening of Two-Way RC Slabs with Textile-Reinforced Mortar: Experimental Investigation and Design Equations

The application of textile-reinforced mortar (TRM) as a means of increasing the flexural capacity of two-way reinforced concrete (RC) slabs is experimentally investigated in this study. The parameters examined include the number of TRM layers, the strengthening configuration, the textile fibers material (carbon versus glass), and the role of initial cracking in the slab. For this purpose six largescale RC slabs were built and tested to failure under monotonic loading distributed at four points. It is concluded that TRM increases substantially the precracking stiffness, the cracking load, the postcracking stiffness, and eventually the flexural capacity of two-way RC slabs, whereas the strengthening configuration plays an important role in the effectiveness of the technique. Simple design equations that provide good estimation of the experimental flexural moment of resistance are proposed

Out-of-plane strengthening of URM walls with fabric-reinforced-cementitious-matrix (FRCM)

Masonry as a building technology meets many of the attributes of sustainable construction, thus an economical alternative to demolish-rebuild existing deficient masonry structures is to retrofit them with novel strengthening systems. Current retrofit techniques used to improve flexural capacity of un-reinforced masonry (URM) walls include both internal and external reinforcement with common materials, namely: steel bars, plates, and most recently fiber-reinforced polymers (FRPs). However, significant margins exist to advance these rehabilitation systems by addressing economic, technological, and environmental issues. This paper investigates the effectiveness of strengthening URM walls using carbon fabric-reinforced cementitious matrix (FRCM) as a technique to enhance pseudo-ductility and flexural capacity. The paper reports on the results obtained by testing a total of 18 masonry walls made of clay bricks and concrete blocks strengthened with two different FRCM schemes (one and four fabrics) subjected to uniformly distributed out-of-plane loading were tested. Experimental data from other research programs using FRP system are also presented to show that when normalized flexural capacity is related to a calibrated reinforcement ratio, the two technologies provide similar enhancements

In-plane behavior of unreinforced masonry walls strengthened with fabric-reinforced cementitious matrix (FRCM)

Un-reinforced masonry (URM) walls have proven to have low shear strength to withstand in-plane loads caused by earthquakes. Retrofitting masonry walls with novel materials such as fiber-reinforced composites has shown to increase the in-plane shear capacity of the walls and minimize damage by enhancing pseudo-ductility. In this study, a new fabric-reinforced cementitious matrix (FRCM) composite system is applied to URM walls to determine its feasibility as an externally-bonded retrofitting technique. The experimental program consists of testing under diagonal compression a total of 18 wall specimens, made from clay bricks and concrete blocks with two FRCM strengthening reinforcement schemes (one and four plies fabric). The experimental results demonstrate the effectiveness of FRCM strengthening on improving the shear capacity of masonry walls. Experimental data from other research programs using fiber reinforced polymer (FRP) composites are presented to demonstrate that when the normalized shear capacity is related to a calibrated reinforcement ratio, the two technologies show similar enhancements

Out-of-Plane Behavior of URM Walls Strengthened with Fabric-Reinforced Cementitious Matrix Composite

The use of unreinforced masonry (URM) walls is common practice in different types of construction, such as interior or exterior walls. URM walls are typically deficient in flexural capacity when subjected to out-of-plane loading caused by high wind pressure or earthquakes. Retrofitting masonry walls with novel materials, such as fiber-reinforced polymer (FRP) composites, has shown enhancement of the flexural capacity and pseudoductility. This study evaluates the feasibility of fabric-reinforced cementitious matrix (FRCM) as an alternative external strengthening technology to improve out-of-plane behavior of URM walls. This paper reports experimental results on flexural capacity of nine clay brick walls of which six were strengthened with two different amounts of FRCM, namely one and four reinforcement fabrics. Experimental evidence shows significant improvements in the structural performance in terms of flexural capacity and stiffness of the strengthened walls. An analysis, disregarding arching effect, is conducted, and its results are compared with the experimental database. From here, the design limits are discussed. Finally, experimental data from other research programs using FRP are reported to show that when flexural capacity is related to a calibrated reinforcement ratio, the two technologies are equivalent

Flexural Strengthening of RC Beams with an Externally Bonded Fabric-Reinforced Cementitious Matrix

Concrete structures deteriorate for various reasons and upgrading is needed to ensure their continued safe working conditions. Retrofitting reinforced concrete (RC) beams have been accomplished using various techniques, namely, steel plates, external posttensioning, externally bonded fiber-reinforced polymer (FRP), and near-surface-mounted FRP systems to increase flexural and shear capacity. The objective of this paper is to investigate the feasibility of fabric-reinforced cementitious-matrix (FRCM) materials as an alternative external strengthening technique for RC members. The FRCM is a composite material consisting of one or more layers of cement-based matrix reinforced with dry-fiber fabric. The experimental program consists of testing 18 RC beams strengthened in flexure with two different FRCM schemes (one and four reinforcement fabrics). An analysis and design are conducted following the well-established formulation to calculate the flexural capacity of the beams and compare their results with the experimental database

URM Walls Strengthened with Fabric-Reinforced Cementitious Matrix Composite Subjected to Diagonal Compression

Unreinforced masonry (URM) walls have been constructed for the past millennia and are still widely used today. URM walls have proven to have low shear strength and are prone to brittle failure when subjected to in-plane loads caused by earthquake or wind. Retrofitting URM walls is accomplished internally and externally using current techniques, such as placing steel bars in the cavities and grouting, posttensioning with steel tendons, stitching, and adhering fiber-reinforced polymers (FRP) to increase capacity and enhance pseudoductility. In this study, a fabric-reinforced cementitious matrix (FRCM) system is applied to URM walls to determine its feasibility as an alternative external strengthening technology. The experimental program consists of testing a total of nine clay brick walls under diagonal compression. Two FRCM strengthening reinforcement schemes are applied, namely, one and four reinforcement fabrics. An analytical model is used to calculate the shear capacity of strengthened URM walls and compare its results with the experimental database. The effect of limitations in design approach on shear capacity of strengthened walls is discussed