The basement of Tianlu Shang Ceng cracked.

Generally, the cracking starts from above the inverted mouth of the constructed concrete and ends below the bottom of the side beam. The crack direction is vertical, the starting and ending are thin, and the middle is thick, showing a spindle shape. The wall-attached column will not crack, but it often cracks when the distance between the two sides of the wall-attached column is 500~ 1000. The vertical crack spacing is 2 2~ 10/0m. The higher the strength, the greater the thickness, the worse the maintenance, and the lower the reinforcement ratio of the wall, the easier it is to crack.

The main reason, or internal cause, lies in the shrinkage and cracking of concrete. The stiffness of basement floor and floor beam is large, which greatly restricts the shrinkage and deformation of basement wall and basically does not produce deformation. In the middle of the upper and lower beams and slabs, the concrete external wall can freely dry and shrink, and the contraction and tensile stress will cause vertical cracks. However, the rigidity of the column attached to the wall is large, and the two sides of the column attached to the wall are the parts with the greatest tensile stress, which often crack.

The secondary reasons are insufficient reinforcement of anti-crack structure, excessive drying shrinkage caused by unreasonable concrete mix ratio and insufficient maintenance.

The solution is also to start from the above aspects. Choose 60-day strength concrete to reduce cement consumption; Reduce the hydration heat of concrete; Reduce cement consumption (avoid drying shrinkage); Reasonable content of fly ash; Increase the structural reinforcement (thin and dense is preferred), within 200, and put it outside the vertical reinforcement. After 400, the overall section reinforcement ratio is greater than 0.5%; Curing with formwork 14 days or more.