混凝土桥梁在常规静、动荷载及次应力直接应力裂缝是由外荷载引起的直接应力

The direct stress cracks of concrete bridges under normal static and dynamic loads and secondary stress are cracks caused by direct stress caused by external loads. The reasons for the cracks are: (1) Calculation or partial omission of calculation at the design calculation stage; unreasonable calculation model; structural force assumption does not match the actual force; load is undercounted or missed; internal force and reinforcement are calculated incorrectly; structural safety factor Insufficient; the possibility of construction is not considered in the structural design; the design section is insufficient; the steel bar is set less or the layout is wrong; the structural rigidity is insufficient; the structure is not handled properly; the design drawings are not clearly explained. (2) Construction stage. Stack construction equipment and materials without restrictions; do not understand the stress characteristics of prefabricated structures; turn over, lift, transport, and install at will; do not construct according to the design drawings; change the construction sequence of the structure without authorization; change the force mode of the structure. (3) Use stage. Heavy vehicles exceeding the design load cross the bridge; hit by vehicles or ships; strong winds, heavy snow, earthquakes, explosions, etc. The cracks produced below are called load cracks, which can be summarized as primary and secondary stress cracks.

The direct stress crack of concrete bridge in conventional static, dynamic load and subshed stress is a crack caused by direct stress caused by external load. The reasons for the cracks are: (1) the design calculation stage calculation or partial leakage, the calculation model is unreasonable, the structural force assumption does not match the actual force, the load is less calculated or missing, the internal force and distribution rib calculation is wrong, the structural safety factor is not enough, the structure design does not consider the possibility of construction, the design section is insufficient, the steel bar setting is small or the arrangement is wrong, the structure stiffness is insufficient, the structure is not handled properly, and the design drawings are not clear. (2) Construction phase. Unbridled stacking of construction tools and materials, lack of understanding of the force characteristics of prefabribriced structures, casual roll-up, lifting, transportation, installation, non-construction according to design drawings, unauthorized changes in the structure construction order, change the structure of force mode. (3) Use phase. Heavy vehicles exceeding the designed load cross the bridge, impacted by vehicles and ships, high winds, heavy snow, earthquakes, explosions, etc. The cracks produced under the load are called load cracks, which are mainly mainly main and secondary stress cracks.

The direct stress crack of concrete bridge under normal static, dynamic load and secondary stress is caused by direct stress caused by external load. The causes of cracks are as follows: (1) In the design and calculation stage, the calculation or partial omission; the calculation model is unreasonable; the structure stress assumption is inconsistent with the actual stress; the load is calculated less or omitted; the calculation of internal force and reinforcement is wrong; the structure safety factor is not enough; the possibility of construction is not considered in the structural design; the design section is insufficient; the reinforcement is set too little or arranged wrongly; the structural stiffness is insufficient; the structure is not handled properly; the design drawing is designed The explanation of paper is not clear. (2) Construction stage. The construction machinery and materials are piled up without restriction; the mechanical characteristics of prefabricated structure are not understood; the body is turned over, lifted, transported and installed at will; the construction is not carried out according to the design drawings; the structural construction sequence is changed without authorization; the structural stress mode is changed. (3) Use phase. Heavy vehicles exceeding the design load cross the bridge; impacted by vehicles and ships; strong wind, heavy snow, earthquake, explosion, etc. The cracks generated under the load are called load cracks, which can be divided into two types: primary and secondary stress cracks.<br>