Abstract:Prestressed simply supported and then structurally continuous T-beam bridges are a commonly used form for spans of 30~50 m. However, during operation, it was found that cracks were commonly present in the web plates of T-beams, mainly in the form of vertical and diagonal cracks. This article mainly studies and analyzes the causes of the eight shaped crack disease in the web plate of the prestressed T-beam consolidation pier area of a certain highway pier. The eight shaped crack is perpendicular to the direction of the shear crack, with a large number and certain development. The crack width exceeds the limit, which affects the safety and durability of the structure. Through statistical analysis and numerical simulation of crack distribution, it has been determined that the root cause of the eight character crack is the inherent deficiency of the structural system, the absence of negative bending moment bundles at the pier top, and the complex stress in the consolidation area of the pier beam, which belongs to the stress disturbance zone. The main reason is that the foundation forms are diverse, and the settlement rate varies in the early stage. When the uneven settlement is greater than 15 mm, excessive tensile stress will occur in the consolidation zone of the pier and beam. The secondary reasons are excessive elongation, shrinkage, creep, and adverse effects on temperature. In addition, the deterioration and accumulation of damage in the performance of bridge structural materials have led to the continuous development of "eight character" cracks. The research results can provide a reference for the design, operation and maintenance of such bridges.
