Fiber-reinforced polymer (FRP) composite materials been widely used in civil engineering new construction and repair of structures due to their superior properties. FRP provides options and benefits not available using traditional materials. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. ACI Committee 440 has published reports, guides, and specifications on the use of FRP materials for may reinforcement applications based on available test data, technical reports, and field applications. The aim of these document is to help practitioners implement FRP technology while providing testimony that design and construction with FRP materials systems is rapidly moving from emerging to mainstream technology.

This volume represents the thirteen in the symposium series and could not have been put together without the help, dedication, cooperation, and assistance of many volunteers and ACI staff members. First, we would like to thank the authors for meeting our various deadlines for submission, providing an opportunity for FRPRCS-13 to showcase the most current work possible at the symposium. Second, the International Scientific Steering Committee, consisting of many distinguished international researchers, including chairs of past FRPRCS symposia, many distinguished reviewers and members of the ACI Committee 440 who volunteered their time and carefully evaluated and thoroughly reviewed the technical papers, and whose input and advice have been a contributing factor to the success of this volume.

A rapid repair or replacement method is developed for severely damaged concrete bridge columns due to cyclic loading. A carbon fiber-reinforced polymer (CFRP) shell and headed steel bars are used to relocate the column plastic hinge. The technique employs a steel collar with steel studs to increase bond of the original column to repair concrete inside the CFRP shell. Two bridge columns were damaged including concrete crushing and longitudinal steel bar pullout under quasi-static cyclic loads. One of the specimens required additional epoxy injection of the cracks; for the other specimen, the column and cap beam were decoupled before repair to simulate replacement of a column which sustained unrepairable damage. The technique successfully relocated the plastic hinge and restored strength and displacement capacity. Failure of the repaired specimens included concrete crushing and bar fracture. The technique is an accelerated bridge construction method and could be used to repair columns with repairable damage or replace columns with unrepairable damage.

The effect of compression reinforcement to reduce long term deflections in GFRP-reinforced concrete beams was evaluated. Nine GFRP-reinforced specimens and three companion steel-reinforced specimens were tested under sustained load for a period of 100 days. Long-term deflection data was used to evaluate the reduction in long-term multiplier for GFRP-reinforced beams and the effects of the compression reinforcement to further reduce the multiplier. Compression reinforcement reduced the long-term multiplier for the GFRP- and steel-reinforced specimens. A new equation is proposed to incorporate the compression reinforcement index, kr, in the long-term deflection multiplier for any type of reinforcement. The experimental results also demonstrate that the ratio of the long-term deflection of a GFRP-reinforced vs. steel-reinforced beam can be determined in a relatively short period of time. Experimental results from the present study show that this ratio is 0.87 for the GFRP-reinforced specimens without compression reinforcement, in lieu of the present 0.6 value used in ACI 440.1R. Keywords:

FRP is customarily used to wrap concrete columns to increase their strength and strain capacities by providing extra confinement. Typically, steel hoops or spirals are used in constructed columns as mandated by codes. The behavior of retrofitted columns becomes thoroughly different because there are two systems with different mechanical response and interaction engaged in confinement. While most of the literature addressed concrete confined with FRP only, a limited number of studies and experimental cases accounted for both actions. This paper developed an axial stress-strain model which utilized geometric and mechanical properties of concrete, steel and FRP. The proposed work adopted Lam and Teng model for concrete confined with FRP, originally implemented in ACI 440.2R-17 guide, and calibrated its parameters against experimental curves. The proposed model correlates well with experimental cases that were collected from the literature.

The current state of North America’s infrastructure system is in dire straits. The cost of repair is estimated at over $3.6 trillion in the United States alone. As an alternative to the current strengthening methods, fabric reinforced cementitious mortar (FRCM) is proposed to aid the civil engineering industry in removing the infrastructure spending gap. This research initiative set out to determine the flexural strength improvement on RC beams with different textile ratios, different fabric materials and different anchorage methods. Five full-scale (200 x 300 x 4000 mm) (8 in x 12 in x 13 ft) reinforced concrete beams (1 control, 4 strengthened) were cast and tested under monotonic four-point bending conditions. Ultimate flexural capacity, pseudo-ductility, stiffness, and failure mode were taken as performance indicators. The study found that flexural strength was improved by up 81% over the control value.