Carbon Fiber Reinforced Polymer Wires Research Articles

Experimental investigation on mechanical performance of carbon fiber reinforced polymer wire after exposure to elevated temperature

The current study experimentally investigated the influence of elevated-temperature exposure on the mechanical performance of carbon fiber reinforced polymer (CFRP) wires through conducting the axial tensile, three-point bending and transverse load tests. The results show that the CFRP wires under axial tensile load exhibited a brittle fracture after exposure to 30 and 100 °C, and the wires after 200 °C exposure were pulled out from the anchorage. The axial tensile and three-point bending performance of the wires were adversely affected by the elevated temperature; and with the increase of the exposed temperature, the maximum contact force, maximum wire tension, maximum wire tension increment, deflection at fracture and the energy dissipation capacity of the preloaded CFRP wires in the transverse load tests declined. Based on the experimental results, reduction functions were established to quantify the degradation in tensile properties of the CFRP wires after elevated-temperature exposure, and the formulas used for predicting the post-elevated temperature transverse failure responses of the preloaded CFRP wires were proposed. Furthermore, through verification by the test results, the previously established failure criteria are demonstrated to be applicable to assess the failure state of a CFRP wire after evaluated-temperature exposure when subjected to combined tension and bending.

Investigation on failure behavior of carbon fiber reinforced polymer wire subjected to combined tension and bending

This study investigated the mechanical behavior of carbon fiber reinforced polymer (CFRP) wires subjected to combined tension and bending through transverse load tests and finite element analysis (FEA). The properties of the CFRP wires were examined through axial tensile and three-point bending tests. Transverse static load tests were conducted on CFRP wires under pretension ratios ranging from 0.00 to 0.85 to investigate the failure responses of the wires. FEA models considering the Hashin failure criteria were developed to reveal the stress state and failure mechanisms of CFRP wires under combined loads. Four failure stages were observed in the three-point bending tests on CFRP wires. The failure of the wires subjected to combined tension and bending loads was caused by fiber tensile fracture at the loading position. With increasing pretension ratio, the longitudinal ultimate load and energy absorption capacity of the CFRP wires increased, while the transverse ultimate load and deflection at fracture decreased. Additionally, an interaction equation at the ultimate state based on internal forces was established for CFRP wires under combined tension and bending.

Effect of temperature on the transverse impact performance of preloaded CFRP wire

This paper experimentally investigated the effect of temperature on the transverse impact response of preloaded carbon fiber reinforced polymer (CFRP) wire. The CFRP wires with a glass transition temperature of 99 °C were tested in the temperature range of −40 to 80 °C using a drop-weight impact test system. The results show that the maximum impact force, maximum wire tension and transverse deflection at fracture of the wire increased as the temperature increased from −40 to 80 °C, due to the ductility of the resin, effective redistribution of internal stresses and reduced stress concentration in the wire at high temperatures; and the energy dissipating capacity was also improved resulting from the low impact damage at high temperatures. A temperature-dependent function to quantify the effect of temperature on the impact response of CFRP wire was established, and formulas for predicting the impact resistance of preloaded CFRP wires at various temperatures were provided.

Transverse Static and Low-Velocity Impact Behavior of CFRP Wires under Pretension

AbstractThe transverse static performance and low-velocity impact response of individual carbon fiber–reinforced polymer (CFRP) wires were investigated experimentally in this study. First, the axia...

Size effect on tensile strength of parallel CFRP wire stay cable

The paper studies the size effect on the tensile strength of parallel carbon fiber reinforced polymer (CFRP) wire stay cable in the macroscale. First, an asymptotic weakest-link Weibull model that incorporates a statistical length effect for the tensile strength of longitudinal composites is proposed in this research. For the proposed model, the weakest-link effect gradually becomes dominant and causes a decrease in strength that increases along the length of the longitudinal elements. The asymptotic threshold length Lρ on the strength analysis can be evaluated by the asymptotic weakest-link Weibull model. The strength data of single carbon fibers and impregnated bundles with different lengths obtained by previous studies are employed to validate the proposed model and the log-likelihood ratio test and the Bayesian information criterion (BIC) are used as the criteria for the validation of the proposed model. The tensile strengths of CFRP wires with different lengths are obtained and analyzed by using the proposed model, and the results obtained from the random strength field model proposed by Vořechovský and Chudoba are illustrated and discussed in detail. Finally, the actual strengths of two parallel CFRP wire cables are compared with the simulated results to illustrate the Daniels’ effect on the strengths of parallel CFRP wire cables. To evaluate the strengths of parallel CFRP wire stay cables, the length effect and Daniels’ effect should be considered in the design of the CFRP cables to ensure safety and reliability.

Seismic performance evaluation and improvement for damaged reinforcement concrete piers using a fiber steel composite plate

The seismic performance evaluation and retrofit process are very important in damaged bridges. If the result is not appropriate, then retrofit process are required. In this paper, to validate the seismic performance of retrofitted bridge experimentally, an experimental study was conducted to verify the application and efficiency of the jacket retrofit method to ensure seismic performance of damaged reinforcement concrete (RC) bridge piers. A total of 4 RC bridge piers was made and then 3 piers were pre-loaded under the range of service load to be damaged. These piers were retrofitted and repaired using a carbon fiber reinforced polymer (CFRP), steel plate, and fiber steel composite (FSC) plates. These retrofitted and repaired piers were subjected to monotonic loading. Hysteresis and ultimate behaviors of the 3 RC piers were evaluated and compared with those of 1 non-damaged pier (standard specimen). As a test result, the retrofitted and repaired RC bridge piers applied by the jacket retrofit method were ensured under the targeted displacement ductility and ultimate load. The ultimate load and displacement ductility of the pier retrofitted and repaired by FSC plate were higher than those of other piers by CFRP and steel plates and also the pier by FSC plate showed better energy dissipation capacity than others. Generally, RC bridge pier retrofitted and repaired with the jacket retrofit method has low ductility but it was found that the pier retrofitted and repaired by FSC plate combined with CFRP and steel wire had overcome effectively this disadvantage through ductility evaluation based on the concept of energy numerically. This experiment showed that one could improve the safety margin and targeted ductility by repairing the cracks, spalls, etc. of the damaged RC bridge piers appropriately and then retrofitting them with the high ductile materials. The responses of existing damage bridges are compared with those of retrofitted bridge by jacket method for earthquake of target level, and also seismic performances are evaluated. By the test and analysis results it can be concluded that the proposed seismic retrofit method was found to be valid.

Influence of service temperature and strain rate on the bond performance of CFRP reinforcement in concrete

Bond of FRP reinforcement is expected to be more sensitive to temperature and rate of loading than conventional steel reinforcement. Present paper introduces experimental results on Carbon Fiber Reinforced Polymer (CFRP) wires of sand coated surface tested by pull-out tests in a multi-parameter laboratory test programme. In the experimental programme low, normal and high strength concretes, −25°C, +20°C and +65°C testing temperatures, and static to impact loads were applied for the pull-out tests (with an order of 1000 in the increase of the rate of loading). Results indicate that the bond strength of the tested CFRP wires follows the change of temperature in a more pronounced manner than the concrete compressive strength does. A viscous-elastic, load rate dependent behavior can be realized in the bond response of the CFRP wires studied. Failure of bond is different for different concrete strengths, testing temperatures and loading rates. Results also indicate that the mathematical functions that are used for the modeling of bond of conventional steel reinforcements are not optimal for the CFRP wires studied.

Reliability Monitoring of CFRP Structural Elements in Bridges with Fiber Optic Bragg Grating Sensors

Fiber optical sensors based on Bragg gratings were used to monitor the strain in suspension or prestressing CFRP (carbon fiber reinforced polymer) cables in bridges. The sensors were either adhered to the surface of the CFRP wires for the suspension cables, or directly embedded during the production process for the prestressing cables, where the load is closer to the limit. Tests for the two applications were performed to validate the suitability of the sensing system. Results accumulated over three years on a stay cable demonstrate the reliability of those sensors.

Reliability Monitoring of CFRP Structural Elements in Bridges with Fiber Optic Bragg Grating Sensors

Fiber optical sensors based on Bragg gratings were used to monitor the strain in suspension or prestressing CFRP (carbon fiber reinforced polymer) cables in bridges. The sensors were either adhered to the surface of the CFRP wires for the suspension cables, or directly embedded during the production process for the prestressing cables, where the load is closer to the limit. Tests for the two applications were performed to validate the suitability of the sensing system. Results accumulated over three years on a stay cable demonstrate the reliability of those sensors.

Connecting high-performance carbon-fiber-reinforced polymer cables of suspension and cable-stayed bridges through the use of gradient materials

Carbon-fiber-reinforced polymer (CFRP) cables offer a very attractive combination of high specific strength and modulus (ratio of strength or modulus to density), outstanding fatigue performance, good corrosion resistance, and low axial thermal expansion. The high specific strength permits the design of structures with highly increased spans. The high specific modulus translates into a high relative equivalent modulus. This factor is very important in view of the deflection constraints imposed on large bridges. A relative high modulus coupled with a low mass density offer CFRP cables already an advantage for spans above 1000 m. Since 1980 EMPA has been developing CFRP cables for cable-stayed and suspension bridges that are produced as assemblies of parallel CFRP wires. The key problem facing the application of CFRP cables, and thus their widespread use in the future, is how to connect them. A new reliable anchoring scheme developed with computer-aided materials design and produced with advanced gradient materials based on ceramics and polymers is described. Early 1996 such CFRP cables with a load-carrying capacity of 12 MN (1200 metric tons) have been applied for the first time on a cable-stayed road bridge with a 124-m span. Each cable is built up from 241 CFRP wires having a diameter of 5 mm.