For steel structure factory buildings with a long service life, reinforcement and renovation are often necessary. Based on practical engineering experience, when reinforcing and renovating steel structure factories that have been in use for 15 to 20 years or more, a qualified testing unit is required to conduct reliability and seismic testing and identification of the factory structure, and make an identification report. Afterwards, the design unit will carry out reinforcement and renovation design based on the identification report.
The reinforcement plan for the steel structure factory building needs to be comprehensively considered based on process requirements, Party A’s requirements, structural layout, and minimizing the impact on production. If necessary, it needs to be jointly agreed upon with Party A and the construction unit
1： Basic requirements for reinforcing steel structure factory buildings
When there is a testing and identification report, the reinforcement suggestions put forward should be fully considered.
When the original structural material is foreign steel, based on the original data, it is necessary to conduct sampling inspections on various indicators of its mechanical properties and chemical composition, and make a comprehensive evaluation.
3. The reinforcement plan for the steel structure factory building needs to be comprehensively considered based on process requirements, Party A’s requirements, structural layout, and minimizing the impact on production. If necessary, it needs to be jointly agreed upon with Party A and the construction unit.
When the steel structure factory building designed according to the old specifications needs to be reinforced and renovated, the original factory building structure must meet the requirements of the current specifications (GB50017-2003 “Code for Design of Steel Structures”, GB 50009-2012 “Code for Load of Building Structures”, GB 50011-2010 “Code for Seismic Design of Buildings”).
5. For structural damage caused by high temperature, corrosion, cold brittleness, vibration, uneven settlement of the foundation, corresponding measures should be taken to reduce, resist or eliminate the impact of these adverse factors during reinforcement, that is, corresponding countermeasures should be taken before considering the reinforcement of the steel structure factory to ensure the reinforcement effect and avoid the structure from being damaged again due to the same reasons after reinforcement.
2： The conditions for welding reinforcement of reinforced components in steel structure factory buildings under load
The reinforcement of steel structure factory buildings generally adopts the method of increasing the cross-section and welding seam connection for reinforcement. In the factory renovation project, in order to meet the requirement of the first party not affecting production, the reinforcement of frame beams, columns, platform longitudinal beams, roof trusses, roof beams and other components generally requires welding reinforcement under load. According to Article 5.1.3 of CECS77:96 “Technical Specification for Steel Structure Reinforcement”, the design working conditions of the reinforced components include welded structures under Class I extremely heavy dynamic loads; Class II structures that directly bear dynamic or vibration loads, except for Type I; Except for Class IV, there are four major categories: Class III structures that only bear static loads or indirect dynamic loads, and Class IV structures that are subjected to static loads and allow for plastic design.
To meet the conditions for welding reinforcement under load, the original structure needs to be verified before reinforcement construction to determine the unloading conditions before reinforcement (such as limiting live loads, removing large roof panels, limiting crane operation during reinforcement, etc.), and detailed instructions should be provided in the design drawings. When the upper and lower chords of the truss components need to be reinforced under load, updating treatment should generally be adopted.
