First, the basic positioning axis and support surface elevation is extremely poor
The base positioning axis and the support steel cylinder surface elevation exceed the allowable deviation of the specification. The reasons are: the basic measurement and control network, the basic measurement of payoff, find the standard high errors, bias. The foundation template support is not strong, pouring concrete under the material is too high, concrete vibrating impact, so that the template displacement, resulting in deviation of the baseline. Or the use of steel ruler, theodolite, the level is not verified, there is error. Or construction of the wrong drawings, the axis of the wrong, without strict inspection. Or the base bearing surface without secondary pressure, leveling, concrete settlement shrinkage sink. Or on the embedded steel (or bearing) did not take fixed measures. As the basic positioning axis and bearing surface tolerance, will lead to column mounting axis and bearing elevation of ultra-poor, affecting the quality of the entire structure of the installation works.
(1) the basic measurement and control network, the basic measurement of the line and leveling equipment, measuring tools, precision should be accurate, must be checked before use or by the measurement department verification and found that the problem in time to prevent errors or produce cumulative error, resulting in the axis And the elevation exceeds the allowable deviation.
(2) the basic template support must be strong, should have sufficient strength and stiffness. In the pouring of concrete cutting and vibrating, to prevent the impact of the template, resulting in displacement. In the process of pouring concrete, should be regularly with a measuring tool or hanging line to check the positioning axis, elevation, such as the discovery of deviation, should stop pouring, vibrating, after reinforcement and exclusion. Concrete before the final condensate, the basis of concrete surface should be second wiping pressure, leveling. On the embedded steel plate or bearing should be corrected by the secondary height, level, and to ensure that the bottom of the concrete dense. The base support column steel plate or bearing shall be provided with the necessary fixing means to ensure that the position and elevation are correct.
(3) the basis of the vertical and horizontal axis and the column bearing plate steel plate or bearing elevation, the level of tolerance, should be taken as the degree of deviation to be raised for processing. When the tolerance is not serious, can be installed in the column column base displacement, reaming, packing pad to solve. Such as the seriousness of serious, can not adjust the treatment, should be related to the relevant departments to study, set feasible correction program, and then deal with.
Second, the steel roof truss before the installation of the anchor bolts are not checked inspection and acceptance
Before the installation of steel roof trusses, the installation unit shall not inspect and inspect the anchor bolts embedded in the staircase bearing. This is not re-measured, I do not know the embedded limb bolts and design drawings and steel roof truss at both ends of the installation hole size is consistent, to be installed only to find the location, size, elevation or error, The installation is not on the need to hang down on the end of the bolt or roof trimming hole to be trimmed before they can be installed on both the delay period, but also increase the construction costs.
Before the installation of steel roof trusses, civil construction, manufacture and installation of the three sides of the construction of the following stalks to check the following: Check the anchor bolt size, elevation, pitch, thread exposure length, etc. within the tolerable range, the span is consistent with the steel structure, and Whether the drawings meet the requirements. After the acceptance of the acceptance, before the steel roof truss to install, to ensure that the installation location, elevation, span and so correct.