Experimental investigation on flexural behavior of concrete-filled pentagonal flange beam under concentrated loading

• We propose a new type of composite beam – concrete-filled pentagonal flange beam (CFPFB).
• We conducted two CFPFB test specimens, one with a pair of stiffeners at mid-span and the other without.
• The FE models are verified in reasonably good agreement with the test specimens.
• The ultimate capacity of the specimen with stiffeners is larger than that without stiffeners.

The flexural behavior of simply supported concrete-filled pentagonal flange beams (CFPFBs) under mid-span loading is experimentally and numerically investigated. There are two CFPFB specimens tested to failure under static load condition to determine the beam flexural capacity. One of the test specimens is designed with a pair of transverse stiffener at mid-span while the other is without any stiffener to resist the load. Both the test specimens have identical geometrical and material properties. From the experimental results, the flexural capacity of the specimen with stiffener is found to be 10% higher than that of the specimen without stiffener. The failure behavior shows the importance of transverse stiffener to enhance the ultimate flexural capacity and to avoid the localized web distortion of the beam. In the numerical study based on finite element (FE) analysis, the concrete and steel materials are modeled using the eight-node solid and four-node shell element respectively. A comparison of the ultimate capacity of the CFPFBs with and without stiffener reveals that the FE models simulate very well the flexural behavior of the test specimens and the difference of maximum load is found to be less than 10%.