工程研究——跨学科视野中的工程2025，Vol.17Issue(3)：313-327,15.DOI:10.3724/j.issn.1674-4969.20240063
在役多层钢框架梁柱节点加固方法及加固后性能研究
Study on Reinforcement Method and after-Reinforcement Performance of Beam-Column Joints in an in-Service Multi-Story Steel Frame
摘要
Abstract
With the increase of the stock and service time of in-service steel structures,the reinforcement of existing steel structures has become an important demand in structural engineering.In this study,the typical middle column joints in an in-service multi story steel frame structure were evaluated.The steel frame structure is in the area with the seismic fortification of 8 degrees,including 5 stories above ground and a basement.The analyzed joint in the steel frame included the welded flange connections and the bolted web connections,and the beam section is enlarged near the connections by increasing the beam depth.According to the standard for seismic design of buildings(2024 edition,GB/T 50011-2010),the joint can satisfy the requirements for the section modules of variable section beams,as well as the requirement for the panel zone yield strengths.However,the original joint in the steel frame cannot meet the requirements for the strong joint-weak member criterion,or pass the ultimate moment resistance check considering the connection coefficient.Furthermore,with the consideration of the 70 percent strength reduction of the welds due to the welding quality,the risks of the joint unexpected failure would further increase.Therefore,local reinforcement of the joint is required to guarantee the safety of the steel frame structure. Finite element models were established in the software ABAQUS for the analysis of the joint behaviour before and after reinforcements.Solid elements were used in the models,and the material properties were simulated by the bilinear dynamic hardening constitutive relationships with von Mises yielding criterion.The interaction between the welds and the corresponding steel plates in the joints were simulated by tying,and the contacts in the bolted connections were considered by penalty function in the tangential direction and hard contact in the normal direction.The friction coefficients for the beam web-connecting plate contacts and the bolt nut-steel plate contacts were taken as 0.35 and 0.05,repsectivley.The beam-end loads were controlled by the inter-story drift angle according to the American seismic design code for steel structures ANSI/AISC 341. Based on the safety and seismic assessment results of the prototype steel frame structure,and in accordance with the current seismic assessment standard for buildings(GB/T 50023-2009),the comprehensive safety assessment of the structure is rated as Deu level and the seismic capacity assessment is rated as Dse level,which has seriously affected the overall safety of the structure.As the original design cannot meet the requirement of strong beam-weak column,firstly the columns were reinforced by welding angle steel at the four corners of the box column.Then,three kinds of reinforcement schemes,including welding steel plates on the beam flanges marked as JG-1,welding vertical stiffeners based on JG-1 marked as JG-2,and welding triangular plates on the lower flange of the beam marked as JG-3,are proposed,and the seismic performances of the joints after reinforcement are studied by finite element numerical simulation.Under axial force and the beam end cyclic loads,the stress development,failure mode and hysteresis performance and main performance indicators of the reinforced joints are the focus of the analysis.The stress distribution and development trend of the three reinforcement forms are generally the same.After reinforcing the original joints,the plastic deformations of the joint are transferred to the beam cross-section.The beam and reinforcement plate have a good synergistic effect,achieving the purpose of joint reinforcement.Also,the joints after reinforcements would develop full hysteresis curves under cyclic loads,indicating satisfactory plastic deformability and good seismic performance.Generally,compared to the original joints,the joints after reinforcements can develop increased resistances,with the ultimate moment resistances of the joint JG-1,JG-2 and JG-3 increasing by 20.29％,19.67％and 22.62％,respectively.Also,all the reinforced joints show better ductility. Besides the mechanical behaviors,the carbon emissions and costs of different reinforcement schemes based on the amount of steel used and actual construction were also calculated to further evaluate different reinforcing configurations and choose the most economical and carbon friendly scheme.Based on the standard for carbon emission calculation of buildings(GB/T 51366-2019),the emission factor method is used to account for carbon emissions during the reinforcement process,expressed in terms of carbon dioxide equivalent.The carbon emissions in three stages,including the material producing,the material transportation,and the field construction,were considered.Multiple factors affecting carbon emissions were considered in the analysis,including the consumption of building materials,transportation distance of materials,carbon emission factors of transportation vehicles,construction energy consumption,and welding engineering quantity.Among the three reinforcing configurations,the cost for JG-1 is the largest,while JG-2 would develop the most carbon emissions. Considering steel consumption,reinforcement costs and carbon emissions,welding triangular steel plates on the upper and lower flanges of the beam is the optimal reinforcement form.The performance and results of each scheme can provide reference for the reinforcement design of existing steel frame beam-column joints.关键词
既有建筑/钢框架结构/节点加固/有限元分析/碳排放计算Key words
existing buildings/steel frame structure/joint reinforcement/finite element analysis/carbon emission calculation分类
土木建筑引用本文复制引用
刘学春,刘德芳,陈学森..在役多层钢框架梁柱节点加固方法及加固后性能研究[J].工程研究——跨学科视野中的工程,2025,17(3):313-327,15.基金项目
国家自然科学基金青年基金项目(52108105) （52108105）
