دانلود رایگان مقاله تحقیقات صورت گرفته روی رفتار شکست فیبر ترکیبی بتن آرمه

Abstract

In the present study, Mode-I fracture tests of hybrid fiber reinforced concrete (HFRC) composite beams were conducted and the fracture properties and other post peak strength characteristics of the HFRC composites were evaluated and analyzed. The HFRC composite was produced using three types of fibers namely steel, Kevlar and polypropylene. A total of 27 HFRC composite beam specimens were cast and tested using the RILEM recommended three point bending test. The main variables were the fiber volume content and combinations of different fibers. The load versus crack mouth opening displacement (CMOD) curves of HFRC composite beams were obtained. Inverse analysis was carried out to determine the tensile strength and crack opening relationship. Analytical models based on comprehensive reinforcing index were developed for determining the influence of the fibers on fracture energy, flexural tensile strength, equivalent tensile strengths and residual tensile strengths of HFRC composites. Based on the experimental results and inverse analysis, a model for predicting the tensile softening diagram of HFRC composite mixes was also developed. The analytical models show conformity with the experimental results.

6. Conclusions

Experimental investigations on Mode-I fracture and post cracking behavior of HFRC composite have been carried out using the RILEM recommended three point bending test. The load versus crack mouth opening displacement (CMOD) curves of HFRC composite beams were obtained. Inverse analysis was also carried out. Influence of the different fibers used in the production of the HFRC composite on the post-cracking behavior of HFRC composite was investigated. Analytical models in terms of comprehensive reinforcing index were developed for determining the influence of the fibers on the fracture properties of HFRC composites. The following conclusions were drawn from the study:
The increase in SF fiber volume results in increase in the fracture properties of HFRC mixes. The replacement of SF fibers by KF fibers causes either almost no change or small decrease in the values of fracture properties of HFRC. The replacement of SF fi- bers by equal volume of PF fibers causes either no change or small increase in the fracture properties of HFRC composites.
Analytical models based on reinforcing index were developed for determining the fracture energy and flexural tensile strength which can be used for the mix design of HFRC composites.
An analytical model is developed for predicting the tensile softening diagram of HFRC composite. The parameters required for the model are based on reinforcing index of hybrid fibers. The analytical model gives reasonable estimate of the tensile softening diagram of HFRC composites.