In building construction, some accidents sometimes occur, such as man-made and material problems. Let's look at the causes of the accident.

Accidents due to problems of supporting materials

The wall thickness does not meet the specification requirements: the design specification of the formwork support is not up to the standard, the service life is long, the corrosion is serious, the local thinning is uneven, and the bearing capacity is greatly reduced. Bending deformation: there is deformation and bending after repeated use, and the bending deformation is not considered in the design of the formwork support system, which leads to a significant reduction in the bearing capacity. There is no specially-assigned person to check and accept the quality of the materials entering the site, which is often only the measurement of the length, and there are no specific requirements in the lease contract, which is convenient for the subcontractor to fake and maximize the benefits.

Reasons for formwork support construction

Inadequate bearing capacity of foundation: the soil is not compacted and hardened, and the bearing capacity cannot meet the calculated stress requirements, resulting in deformation and uneven settlement under the load and rain and water immersion, leading to the instability of the support. Vertical pole lengthening: when the vertical pole is erected with a high height or a short steel pipe is used as a support column, the stability of the vertical pole is extremely unfavorable, but the existence of connection nodes is not considered in the specification and theoretical calculation. In fact, the connection point is a weak link that is prone to bending deformation. As long as the vertical pole is slightly eccentric in force, and the lateral deformation is large, eventually the entire support system will be damaged and collapse accident will occur. Lack of bottom horizontal bars and horizontal tie rods: the specification requires that the formwork support must be equipped with longitudinal and transverse bottom horizontal bars and horizontal and longitudinal tie rods. In actual construction, the absence or lack of longitudinal and transverse bottom horizontal bars increases the calculated length of the upright and weakens the stability of the upright. No or less shear bracing: in most formwork collapse accidents, it is not due to insufficient bearing capacity of steel pipe but due to insufficient lateral deformation resistance, instability of support system or local instability of member. There is eccentric load on the upright pole of the support: when the eccentricity of the axis of the vertical and horizontal horizontal horizontal pole and the axis of the opposite pole is not more than 55 mm, the eccentric effect can not be considered in the stability calculation of the upright pole. When connecting with fasteners in the operation, they are not close to each other on the main node. The eccentricity is greater than the specification, resulting in additional bending moments. There are uncertainties in the influence of eccentric bending moments on the stability of the formwork support. The spacing of formwork support poles is too large: the support poles are the main load-bearing poles of the stress system, and the spacing should be determined by calculation. However, in the actual construction, the spacing of the poles and the step spacing of the vertical and horizontal horizontal poles are too large, and are not evenly arranged, resulting in the insufficient bearing capacity of the main load-bearing poles of the formwork, which is the main factor causing the collapse of the formwork support.

Construction management reasons

The technical personnel did not carry out technical disclosure and signature to the construction team leader and all construction personnel before construction, or the content of the disclosure was inconsistent with the actual construction and special plan. The construction personnel have low skills and have not received skill training and passed the examination. During the erection of the support and before the pouring, it failed to track, inspect, supervise and rectify, and failed to find problems in time; The inspection responsibility is not implemented, the problems found are not corrected and rectified in time, and the concrete is poured in a hurry when there is a gap with the plan. The investment in safety production costs is insufficient, the investment in revolving materials is insufficient, and the safety measures are not in place. During the actual construction, the tightening torque of the fastener bolts was not checked or the inspection quantity could not meet the specification requirements. Only by feeling and experience, the acceptance was not recorded, and the overall stability of the support system could not be guaranteed. There is no supervision or unified dispatching during concrete operation.

In short, to eliminate some human factors, for some product quality problems, builders should choose high-quality template support system manufacturers