Bending Behavior Of Internally Prestressed Composite Beams With Corrugated Steel Webs

Prestressing technology greatly promotes the development of corrugated steel webs composite girder bridges,and makes the bridge structure hacve the advantages of clear force,reduced self-weight and increased span.Most of the existing corrugated steel webs composite girder bridges use external prestressing cable system,but the system is expensive and vulnerable to rain,chloride and other erosion in the natural environment.Therefore,the use of external prestressing cable system will not only increase the cost of construction and later maintenance of the girder bridge significantly,but also leave potential safety hazards to the structure.Based on the above problems,a new type of internal prestressing corrugated steel webs composite beam structure is proposed in this paper.The structure cancels the lower flange concrete slab of traditional corrugated steel webs composite box girder,and uses two rectangular steel boxes to connect with steel webs.The rectangular steel box is filled with concrete to form a small concrete steel box,and the pre-stress in the tensioned body is reserved in the concrete steel box.The main contents of this paper are as follows:(1)A new structure of composite beams with corrugated steel webs is proposing.Based on the related single beam theory,the mechanical characteristics of the structure are preliminarily analyzed.Four specimens with different parameters are designed.The three parameters of prestressing,concrete slab thickness and web form are compared.The failure modes,bearing capacity,strain distribution law of section and increment of prestressing force of each specimens are studied and analyzed.Static performances such as prestressing efficiency,etc.The results show that increasing the prestressed system and the thickness of concrete slab can significantly increase the overall initial stiffnessof the structure,and ultimately improve the overall flexural performance of the specimens.Compared with the core specimens PZ-5,the existence of prestressing increases the ultimate flexural capacity of composite beams by21.2%.The change of concrete slab thickness and web form has little effect on the ultimate flexural capacity of composite beams,and the increase is less than5%.(2)Considering the non-linearity of material,the finite element calculation is carried out for the test specimens.Four test specimens and the finite element calculation are compared and analyzed.The results show that the load-deflection curves and stress laws of the two specimens are basically the same,and the accuracy of the modeling method is determined.Based on the test specimens,the parameter analysis of the internal prestressing corrugated steel web composite beams is carried out,and the extended modeling calculation of eight different specimens is carried out.The effects of web height,concrete axial compressive strength,span and effective prestressing parameters on the flexural properties of composite beams,such as mid-span displacement,ultimate bearing capacity and stress distribution along beam height,are studied.The results show that the flexural rigidity of the mid span section can be improved by increasing the web height,the concrete strength and the effective prestressing force,so as to improve the overall flexural performance of the specimen.In addition,the flexural performance of composite beams with different span parameters has a great influence.The ultimate loads of PZ-9 and PZ-10 are reduced by 27.1%,37.8%,and the ultimate displacements are increased by 66.9% and 107.4%,respectively.The research work in this paper can provide reference and basis for the study of flexural behavior of internal prestressing corrugated steel webs composite beams.