Flexural resistance and deformation behaviour of CFRP-ULCC-steel sandwich composite structures

This paper experimentally and analytically investigates the flexural behaviour of carbon fibre-reinforced polymer (CFRP)-ultralightweight cement composite (ULCC)-steel sandwich composite members filled with a novel ULCC. The flexural resistance and deformation behaviour of sandwich composite members manufactured with various section configurations, internal tube eccentricity and internal tube materials are compared. Four-point bending tests reveal that all of the composite members exhibit ductile flexural failures. The internal tube eccentricity and metal materials significantly affect the flexural resistance, whereas the internal tube configuration has a moderate effect. The composite members with circular internal tubes exhibit greater ductility and flexural resistance than those with rectangular tubes. Two analytical methods the simplified method and fibre element approach, which consider the section configurations, tube eccentricity and material properties based on the strain compatibility principle are developed to predict the composite members' flexural resistance. Moreover, two section classifications are presented. Typical confined concrete models and uniaxial concrete models are used for predicting flexural resistance. The derived models are verified against test results reported here and elsewhere; the confined concrete model provides unconservative flexural resistance predictions, whereas the uniaxial concrete model provides close, conservative predictions. A stepwise approach is proposed for designing lightweight CFRP-ULCC-steel sandwich composite members.

Automated summary

This study experimentally and analytically investigated the flexural behavior of CFRP-ULCC-steel sandwich composite members, finding that internal tube eccentricity and material selection significantly affect flexural resistance, with composite members with circular internal tubes exhibiting greater ductility and flexural resistance.