Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of t...Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well.展开更多
Concrete-filled rectangular steel tubular(CFRST)composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab.This new type of bridge has the advantages of high structural force-tr...Concrete-filled rectangular steel tubular(CFRST)composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab.This new type of bridge has the advantages of high structural force-transferring efficiency,rapid assembly construction speed and excellent total life cycle,which meets the construction concept of green,recyclable and sustainable development.Due to the broad application prospects,experiment on the flexural behavior of CFRST composite truss bridge in the negative moment region was reported by authors previously.This paper thus presents a finite element analysis(FEA)modelling verified by the reported test data to further investigate the detailed analytical behavior of this structure.The structural response and failure mechanism of CFRST composite truss beam in the negative moment region are studied.In addition,the important structural design parameters on the flexural performance of the CFRST composite truss beam are also investigated,including the height to span ratio,the brace-to-chord wall thickness ratio,the reinforcement ratio of steel reinforcements and prestressed tendons and the strength grade of concrete infill in chords.Finally,the reasonable structural design parameters range are proposed for the optimum design of the CFRST composite truss bridge.展开更多
文摘Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well.
基金sponsored by the National Natural Science Foundation of China(No.52008026)Natural Science Basic Research Program of Shaanxi(No.2021JQ-272)the Fundamental Research Funds for the Central Universities(No.300102219310,No.300102211303)。
文摘Concrete-filled rectangular steel tubular(CFRST)composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab.This new type of bridge has the advantages of high structural force-transferring efficiency,rapid assembly construction speed and excellent total life cycle,which meets the construction concept of green,recyclable and sustainable development.Due to the broad application prospects,experiment on the flexural behavior of CFRST composite truss bridge in the negative moment region was reported by authors previously.This paper thus presents a finite element analysis(FEA)modelling verified by the reported test data to further investigate the detailed analytical behavior of this structure.The structural response and failure mechanism of CFRST composite truss beam in the negative moment region are studied.In addition,the important structural design parameters on the flexural performance of the CFRST composite truss beam are also investigated,including the height to span ratio,the brace-to-chord wall thickness ratio,the reinforcement ratio of steel reinforcements and prestressed tendons and the strength grade of concrete infill in chords.Finally,the reasonable structural design parameters range are proposed for the optimum design of the CFRST composite truss bridge.
