钢结构工程施工要求非常的严谨，不容许任何一步出现错误，否则就会影响钢结构工程的施工安全。但是有些事情是无法避免的，钢结构工程施工过程中还是会出现变形等问题，那么是什么原因导致的呢？
The construction requirements of steel structure engineering are very strict, and errors are not allowed in any step, otherwise it will affect the construction safety of steel structure engineering. But some things cannot be avoided, such as deformation during the construction process of steel structure engineering. So what is the reason for this?
一、钢梁起拱问题：起拱的方法，对钢梁有抛物线形起拱和折线形起拱。对门式刚架常采用折线形起拱，也就是在钢梁的拼接节点处，通过控制连接端板的角度，达到起拱的目的。钢梁起拱的目的，主要是对屋面钢梁受荷变形后，起拱量可以抵消一部分变形，其屋面仍能保持一定的坡度。钢梁起拱过大，将会使靠近屋脊处的屋面坡度变小，钢梁变形过大将会使靠近檐口处的屋面坡度变得过小。过大的坡度变化是不恰当的。起拱与否，起多大拱，本身应该是一个设计问题。在设计未要求起拱时拱度允许偏差定为-5~10mm，就是不主张施工方自己定个起拱量。
1、 The problem of steel beam arches: The method of arches includes parabolic and polygonal arches for steel beams. For portal frames, a broken line arch is often used, which is achieved by controlling the angle of the connecting end plates at the splicing nodes of the steel beams. The purpose of arched steel beams is mainly to offset some of the deformation of the roof steel beams under load, and to maintain a certain slope of the roof. Excessive arching of the steel beam will reduce the slope of the roof near the ridge, and excessive deformation of the steel beam will cause the slope of the roof near the eaves to become too small. Excessive slope changes are not appropriate. Whether to arch or not, and how large the arch should be, should itself be a design issue. When the design does not require arch camber, the allowable deviation of arch camber is set at -5~10mm, which means that the construction party is not recommended to set an arch camber amount by themselves.
二、屋面檩条安装不当导致变形过大：有些工程中，刚性系杆、风拉杆的连接板设置位置高低不一，使得水平支撑体系不在同一平面上，从而影响刚架的整体稳定性。刚性系杆与风拉杆构成水平支撑体系，其设置高度在同一坡度方向应保持一致。在屋面或墙面檩条安装中，有些施工单位为了安装方便，随意增大、加长檩条或檩托板的螺栓孔径。檩条不仅仅是支撑屋面板或悬挂墙面板的构件，而且也是刚架梁柱隅撑设置的支撑体，设置一定数量的隅撑可减少刚架平面外的计算长度，有效的保证刚架的平面外整体稳定性。若檩条或檩托板孔径过大过长，隅撑就失去了应有的作用。
2、 Improper installation of roof purlins leads to excessive deformation: In some projects, the connection plates of rigid tie rods and wind tie rods are set at different positions, causing the horizontal support system to not be on the same plane, thereby affecting the overall stability of the rigid frame. The rigid tie rod and wind tie rod form a horizontal support system, and their setting height should be consistent in the same slope direction. In the installation of roof or wall purlins, some construction units arbitrarily increase or lengthen the bolt hole diameter of purlins or purlin support plates for installation convenience. Purlins are not only components that support roof panels or suspended wall panels, but also support the setting of corner braces for rigid frame beams and columns. Setting a certain number of corner braces can reduce the calculated length of the rigid frame out of plane, effectively ensuring the overall stability of the rigid frame out of plane. If the aperture of the purlin or purlin support plate is too large or too long, the corner brace will lose its proper function.