50 years service life for multi-storey frame structure office building addtional layer reinforcement
Project Name: A multi-storey frame structure office building in Zhejiang
Year of Strengthening: 2021
Method: Concrete Section Expansion / Steel Jacketing / Chemical Anchoring
This building was built in August 2014, the building as a whole is “L” shaped layout, the original design is a 6-story local 7-story frame structure, in the construction process the owner requested to add a layer, after adding layers, it is now a 7-story local 8-story frame structure, and the building function does not change. The current office building is 34. 20m, width 27. 70m, construction area of about 4700 square meters. 1, 2 layer height are 4. 50m, 3 ~ 7 layer height are 3. 60m, local 8 layer height is 4. 20m, building height 27. 45m。 The foundation of the office building is a manually dug-hole pile, the pile diameter is 800mm ~ 1100mm, the foundation pile holding layer is a weathered sandstone layer, and its limit end resistance standard value is 3000kPa. The strength grade of frame concrete is C30 and the strength grade of poured pile concrete is C35. During the construction of the structure, the deformation and bearing capacity after adding a layer do not meet the requirements of the specification, and the seismic structure does not meet the requirements of the specification, and the overall reinforcement treatment of the structure is required.
After the office building structure is fully reinforced by the structure, the maximum elastic inter-layer displacement angle in the X direction and Y direction meets the requirements of the specification, the bearing capacity of the frame column and the frame beam meets the design bearing requirements, and the axial pressure ratio of the underlying column meets the specification requirements, so the structural reinforcement is reasonable and effective, and the reinforcement goal is achieved, which meets the design requirements of 50 years after reinforcement.
Through the engineering practice of structural bearing capacity appraisal and calculation, structural reinforcement calculation analysis and reinforcement design after the addition of the office building, the dynamic characteristics of the structure after engineering reinforcement are significantly improved, the deformation of the structure meets the requirements of the specification, and the bearing capacity of the overall structure meets the design bearing requirements, which can meet the design requirements of the subsequent 50 years of use. The outer steel method reinforces concrete components using viscose glue for bonding, because the subsequent service life is 50 years, so the viscose glue needs to use the “Technical Specification for safety identification of engineering structural reinforcement materials” (GB 50728-2011) requires the design of structural adhesives with a service life of 50 years.