Propping Beams & Extracting Column And Structure Strengthening Research Of Steel-structure Factory

The present construction industry has changed the former large-scale construction period into another one that new projects construction and building maintenance and modification coexists. Some buildings need modification, in this case, the propping beams and extracting column method (PBECM) is widely used to enlarge column space. While the theory of PBECM, lift-up technology for upper structure and evaluation for the post modification effect is still not perfect.In this paper, the author analyze deeply on the PBECM for steel structure workshop building and structure strengthening technology based on project, then put forward reasonable modifying scheme through detail field investigation, site survey and craft knowing. Take spatial calculating model to analyze the whole structure with PBECM statically and dynamically and compute precisely the stress, loading character and strength-carrying level of members between pre modification and post modification, and supply evidences for proper selection of strengthening members and measures to ensure the overall stiffness. Get frequency of the first-order mode of pre modification and post modification through spatial calculating model, compare the stiffness differences, and use the field survey technology to monitor the dynamic character of structure, the author get conclusion that the computing analysis matches the field monitoring results well. This further proves that the correction of theoretical analysis and rationality of structure strengthening.It is amply discussed about the modifying-strengthening design and PBECM construction process and put forward integrated design and construction methods in paper. Utilize computer to simulate the whole process of column truncating, lifting up and frame dropping, take the theory to guide construction and ensure safety, monitor the site situation, a conclusion can be reached that the test result matches the result by analysis very well. Meanwhile it is probe into the elementary theory of lift-up technology. Utilize electric resistance strain gauge to monitor main members need strengthening statically and dynamically to ensure the accountability of modifying and strengthening design during the load transferring during PBEC process. The strengthening plates can work together effectively by the monitor result. The strengthening effect is obvious and the PBECM is successful. The systematic and integrated monitor data have very important reference value for the PBECM.Practice show that PBECM have remarkable economic and social benefits. This paper would provide other similar projects with practical experience and theoretical reference and give a modest spur to induce others to come forward with this technology.