Failure mechanism of the arch of concrete filled steel tube supports component

Based on the concrete-filled steel tube (CFST) supporting structure used in deep-seated soft rock roadway, six equivalent loads are loaded on the 1 / 4 CFST circular arches. The influence of mechanical properties with different rise-span ratios and steel fiber volume parameters are studied. The experimental results show that the bottom of CFST circular arch is damaged by compressing,bending and shearing. The apex of arch is mainly influenced by compressive stress. Both apex and bottom of the arch are the weakest cross sections. The bearing load and the stiffness of structure are enhanced with the increase in rise-span ratios. The flexibility is increased in test specimen with 1% -1. 5% steel fiber volume parameters while little difference can be found in ultimate load in contrast to the one without steel fiber. With continuing increase in steel fiber volume,the stiffness of specimen is increasing and ultimate load is decreasing. Therefore,1% -1. 5% volume parameter of the steel fiber is suitable. Besides,by using numerical simulation,the stress forms of the dangerous sections of the specimens and the influence of bearing capacity on the section dimension,rise span ration,wall thickness of steel tubes are further studied. Meanwhile,combined with the experimental analysis and numerical results,theoretical analysis is proposed from three aspects:Section strength,local instability and overall in- stability. The cause of local instability and calculation formula for the ultimate bearing capacity of circular arch CFST are obtained. Finally,on the basis of practical engineering condition,the design example of CFST is introduced.