Design and research on crack resistance measures in negative moment zone of continuous steel-concrete composite beam bridges
To improve the stress performance in the negative moment zone of continuous steel-concrete composite beam bridges and address the problem of deck slab cracking,we conduct a research based on the design of a 4 ×85 m continuous steel-concrete composite beam bridge in a high-speed expansion project in Shenzhen.Using the finite element method,the study investigates the effects of adding prestressing tendons,support lifting method,post-casting,micro-expansive concrete,and increasing reinforcement ratio on the crack resistance performance of the deck slab in the negative moment zone.The re-sults show that post-casting of the deck slab can eliminate tensile stresses caused by the first-stage permanent load;that both the support lifting method and prestressing tendons can introduce pre-compression stress in the deck slab,effectively reduc-ing the stress level of the deck slab;that increasing the reinforcement ratio can only reduce the maximum crack width,and when the reinforcement ratio is less than 1.2％,the maximum crack width of the deck slab decreases rapidly with the in-crease of the section reinforcement ratio,but when the reinforcement ratio exceeds 2.4％,the reduction in the maximum crack width of the deck slab decreases with the increase of the section reinforcement ratio;that the micro-expansive concrete can effectively reduce the tensile stress in the deck slab.Finally,comprehensive crack resistance measures are proposed based on practical project,which can provide a reference for the design of similar projects in the future.
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