How to improve the safety performance of steel structure

With the steel structure workshop in civil, industrial and public buildings in a large number of applications, its safety performance application more and more attention, today we summed up the steel structure of the safety assessment content, let's see.

I. Safety assessment

1. Connection and structure

1) Reasonable setting of weld size, bolt spacing and diameter, rod section size. For example, the section size should meet the design requirements of the minimum section size, steel pipe wall thickness of 3mm, the minimum thickness of steel plate 4mm, the minimum section of Angle steel L45×4mm.

2) Ensure reliable connection between components. Both the connection between components and components, and the connection of components themselves should meet the requirements of the specification. Connection calculation is mainly to detect the effect of the connection, mainly including bearing capacity and tension calculation, welding seam connection strength calculation, column and steel frame structural beam rigid calculation, bolt rivets connected to accept shear calculation and the calculation of the joint plate.

3) Ensure that the local stability of the steel structure can meet the requirements, such as increasing the width to thickness ratio of the section.

4) Heat insulation and protection performance meet the requirements.

5) The overall support of steel structure and the arrangement between members should be scientific and reasonable, and ensure the construction quality of each part, such as strict control of roof truss, vertical support, horizontal and vertical support of truss, etc.

6) Strictly control the processing and installation of bearings, such as verticality, safety flatness and installation of bearings to meet the requirements.

Two, bearing capacity

For steel structural members with corresponding conditions, such as beams, plates or roof frames, vertical loads can be imposed on the site, and then the deflection deformation and lateral strain of key parts can be detected, according to the strain and analysis results to determine whether to meet the bearing capacity requirements.

The implementation of site load test should follow the principle of non-destructive, under the condition of ensuring that the load form is basically consistent with the actual effect of the structure, to avoid irreversible damage or deformation of components or structures caused by site inspection load, so the site inspection and should be set as 70%~80% of the design load. In the field load test, loading and unloading should be carried out in stages, generally reaching the standard value of load through grade 5, and then unloading through grade 2~5. Typically, 20% of the standard value is loaded at the beginning of the load, and then increases by 10% at each level. At the same time, in order not to cause damage, the increase of load should be reduced to 5% when the load value is close to the standard value. Each stage shall last at least 10min after loading, and then test readings shall be taken. For large span roof truss or trusses, the duration should be up to 12h or longer, and the inspection of crack width and deformation should last * 30min less.

Three, steel structure disaster resistance ability

The evaluation of disaster resistance mainly includes fire resistance, earthquake resistance, wind resistance (mainly light steel structure) and snow and ice resistance (mainly steel roof frame). Among them, the seismic capacity is mainly evaluated by the structure and system connection structure, arrangement and the seismic capacity of the structure and components. The evaluation of resistance to snow, ice and wind can be carried out from the selection of steel structure bearing capacity checking and structural connection.