RESEARCH ON THE COMPRESSIVE SHEAR COMPOSITE STRESS OF STEEL FIBER REINFORCED CONCRETE AFTER HIGH TEMPERATURES
This paper studies the steel fiber reinforced concrete(SFRC)after high temperature compressive shear composite mechanics performance under loading.Taking compressive ratio and temperature as the independent vari-able,20 SFRC samples are carried out direct shear tests and shear tests.The failure forms of different SFRC speci-mens are compared and analyzed,and the effectiveness of temperature and compressive stress ratio on shear strength is investigated.Based on three theories,the failure criterion of SFRC under combined compressive shear loading af-ter high temperature is established.The results indicate that SFRC shear strength is mainly composed of contact fric-tion force contribution in the state of combined compressive shear loading.With the compressive stress ratio increas-es,the peak shear strength of SFRC also increases,which decreases with the increase of temperature.With the in-crease of compressive stress,the friction coefficient on the shear plane exhibits a decrease,and the growth amplitude of the peak shear strength decreases.According to the testing data,the compressive shear failure criterias estab-lished based on different theories after high temperature SFRC are compared.Considering the accuracy and applica-bility,the failure criterion established based on the stress invariant theory is with the best effectiveness.