Glass Fiber-reinforced Polymer Shear Connector Research Articles

Design properties of insulated precast concrete sandwich panels with composite shear connectors

Researchers have developed various types of shear connectors to enhance shear transfer in insulated concrete sandwich panels. The shear transfer capacity of a precast concrete sandwich panel (PCSP) system that is composed of two precast reinforced concrete wythes separated by a layer of insulation wythe is influenced by the degree of composite behavior/action. This paper presents experimental results of push-out tests of concrete sandwich panels that use a grid type of glass fiber-reinforced polymer shear connector and then compares these results with previous research results that are based on corrugated shear connectors. A design equation (ICC-ES) was modified for this work to determine the shear strength of PCSPs with various configurations. For this study, 22 double-shear (push-out) specimens were fabricated and tested using two types of insulation materials, three insulation wythe thicknesses, and two grid spacings for the shear connectors as the variables. The test results were used to calculate toughness index and shear modulus values and to calibrate the modified ICC-ES equation. Increasing the thickness of the insulation wythe had a decreasing effect on the maximum shear flow and shear modulus of the PCSP system.

Effect of cyclic loading on composite behavior of insulated concrete sandwich wall panels with GFRP shear connectors

Abstract A full-scale experiment was conducted to investigate the composite behavior of insulated concrete sandwich wall panels (ICSWPs) under monotonic loads and wind-induced cyclic loads. The experimental program consists of two groups, according to the applied loading type and the type of insulation, with the same configurations of glass-fiber-reinforced polymer (GFRP) grids. The degree of composite action in terms of the initial stiffness and ultimate strength were compared at the global level, and the degree of composite action in terms of the shear flow were compared at the local level (in accordance with the variables). The test results showed that the adhesive bonds based on the insulation absorptiveness and the mechanical bonds based on the insulation surface roughness and groove treatment were effective for inducing the desired composite behavior of ICSWPs in both monotonic loading and cyclic loading tests. The cyclic test group showed a lower degree of composite action compared to the monotonic test group at a constant rate. This is the case because cumulative fatigue loading damaged the GFRP strands and debonded the interface between the concrete and insulation. These results indicated that the adhesive and mechanical bonds between the insulation and concrete wythes can be used to estimate the design strength of ICSWPs with GFRP shear grids. Additionally, the reduction factor for the design strength by the fatigue effect should be considered in estimation of design strength.

Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction.

A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs) subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP) shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

Effects of insulation types on in-plane shear behavior of insulated concrete sandwich wall panels with GFRP shear connector

This paper describes the in-plane shear behavior of insulated concrete sandwich wall panels (CSWP) reinforced with corrugated glass fiber-reinforced polymer (GFRP) shear connector. The study included testing 8 insulated CSWP specimens with different types of insulation and corrugated shear connector. All specimens were loaded in direct shear. The test variables were embedment depth of shear connector and removal of adhesive stress between insulation and concrete. Test results indicated that the reinforcement of corrugated GFRP shear connector significantly increased in-plane shear strength. And dispersion reinforcement will be more effective in the case of expanded polystyrene (EPS) insulation. Meanwhile, reinforcement at a degree close to 45° will be more effective in the case of extruded polystyrene with surface treatment (XPSS) insulation. Increase of embedment depth of shear connectors was able to restrain pull-out phenomenon of shear connectors. And removal of adhesive force of insulation tended to decrease in-plane shear strength.

파형 GFRP 전단연결재의 폭 및 너비에 따른 중단열 벽체의 면내전단거동

This paper describes the experimental results of insulated concrete sandwich wall panels (CSWP) with corrugated glass fiber-reinforced polymer (GFRP) shear connectors under in-plane shear loading. Corrugated GFRP shear connectors were used to improve the thermal property of insulated CSWP and to achieve composite action between the interior and exterior concrete wall panels. Test specimens were consist of three concrete panels with two insulation layers between concrete panels and middle concrete panels was loaded in the direction of gravity. To evaluate the effects of insulation types (extruded polystyrene, XPSS and expanded polystyrene, EPS), shear connector pitch (300 and 400 mm) and width (10 and 15 mm) on in-plane shear behavior of insulted CSWP, failure mode and shear flow-average relative slip relationship of specimens were investigated. Test results indicate that the bond stress between concrete panel and insulation is considerable initially. Especially in case of insulated CSWP without shear connector, initial stiffness of CSWP with XPSS is superior to that of CSWP with EPS. The shear connector's contribution to in-plane shear performance of insulated CSWP depends on the type of insulation.

Experimental Investigation of Precast Concrete Insulated Sandwich Panels with Glass Fiber-Reinforced Polymer Shear Connectors

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Influence of Insulation Type on In-Plane Shear Behavior of Insulated Concrete Sandwich Panels (ICSP) with GFRP Grid Shear Connectors

This paper reports the experimental results to evaluate in-plane shear performance of insulated concrete sandwich panel (ICSP) with glass fiber-reinforced polymer (GFRP) grid shear connectors. The variables considered in this study are the grid size (35 and 53mm) of GFRP shear connectors and the types of insulation (expanded polystyrene, EPS and extruded polystyrene with special slots, XPSS). For loading in-plane shear force to interface between inner and outer wall of ICSP system, the ICSP specimens were supported vertically at the bottom edge of the two concrete outer walls by steel blocks. The test results indicate that ICSP with XPSS developed higher shear flow strengths in ICSP with EPS when 35mm spacing of GFRP grid is used. Also, the test results indicated that as the grid spacing of GFRP shear connector decreases, the shear flow strength of ICSP with XPSS insulation was higher, but the shear flow strength of ICSP with EPS insulation was lower.

Shear Reinforcing Influence of GFRP Shear Connectors in the Concrete Sandwich Wall Panel (CSWP) for Exterior Envelopes of Buildings

This paper summarizes the experimental results of concrete sandwich wall panels (CSWP)specimens under pull-out loading conducted to investigate the effect of insulation type and reinforcing area of shear connector made with glass fiber-reinforced polymer (GFRP) on the shear behavior of CSWP used as exterior cladding walls.In this study, two types of thermal insulations;expanded polystyrene(EPS)and extruded polystyrene with special slots(XPSS) and wave-shaped GFRP shear connectors with different reinforcing area; 6mm x 2mm and 12mm x 2mm were used for CSWP specimens.Test results indicated that the types of insulations and reinforcing area of GFRP shear connectors have a significant effect on the direct shear behavior between concrete wall and insulation. As reinforcing area of GFRP shear connector increase, increase in shear strength of CSWP with EPS insulation is less than CSWP specimens with XPSS insulation due to relatively lower strength of EPS compared to XPSS strength.

Effect of GFRP Shear Ties on Shear Behavior of Interfaces between Precast Concrete Panel and Extruded Polystyrene Special Insulation

This paper describes the test results on the direct shear behavior of glass-fiber reinforced polymer (GFRP) shear tie reinforced interfaces between precast concrete sandwich panels (PCSP) and extruded polystyrene (XPS) insulations. The insulated PCSP consists of two concrete panels with 100mm or 80mm thick insulation between inner/outer concrete panel layers. In order to achieve composite action concrete panels are connected by corrugated GFRP shear connector. In this study, three types of couple replicate insulated PCSP with different embedment length of GFRP shear connector were made and loaded in push-out. The test results indicated that the reinforcement of GFRP shear ties for interface between PCSP and XPS insulation improves initial and post-peak shear performance of insulated PCSPs. These phenomena are remarkable for XPS insulated PCSPs with larger embedment length of GFRP shear connectors.

Direct Shear Responses of Insulated Concrete Sandwich Panels with GFRP Shear Connectors

This paper investigates shear flow strength of insulated concrete sandwich panels with glass fiber reinforced polymer (GFRP) shear connectors based on push-out test. The precast insulated concrete panels consist of 60mm concrete wall, 100mm insulation, and 130mm concrete wall. Two concrete walls were connected with GFRP corrugated shear connector. Four specimens with variables such as the insulation type and the width of GFRP corrugated shear connector were made. Failure modes, shear flow-deflection relationships and post-peak strength were investigated. Test results indicate that the specimens with EPS insulation show higher shear flow strength than those with XPSS insulation due to the relatively high surface roughness of EPS insulation, and the shear flow strength increased with increasing shear connector width.

Investigation into the Bond of Glass Fiber–Reinforced Polymer Stay-in-Place Structural Forms to Concrete for Decking Applications

Glass fiber–reinforced polymer (GFRP) pultruded sections have great potential as structural stay-in-place forms for bridge components, including deck slabs. The bond behavior between cast-in-place concrete and GFRP forms, a key consideration in this type of structure, was studied. Eight concrete slabs cast on GFRP plates were fabricated and tested in bending to investigate and compare various bond systems and GFRP reinforcement ratios. No steel reinforcement was used. Bond systems included adhesively bonded freshly cast concrete on the plate, coarse aggregates bonded to the plate before concrete casting, and GFRP and steel mechanical shear connectors. Adhesive bonding to fresh concrete was the most efficient method. Generally, this method resulted in higher flexural stiffness than mechanically connected systems because no slip occurred in the former, whereas progressive slip occurred in the latter from the onset of concrete cracking. Bond failure eventually occurred within a thin layer of cement mortar that remained adhered to the plate. The hybrid slabs were equivalent in strength and stiffness to conventional steel-reinforced slabs of high reinforcement ratios. In addition, the hybrids had the advantage of simple and quick constructability as well as not being hindered by the limitations of concrete cover or rebar spacing. A general analytical model was developed to predict the full behavior and strength of the slabs and was successfully validated. The model can detect various failure modes, including GFRP plate debonding.