Experimental Research On Structural Behavior Of Min-Zhe Timber Arch Bridge

As a branch of China timber arch bridge, Min-zhe timber arch bridge is famous for its unique woven timber arch structure. As Min-zhe timber arch bridge was found late, and few structure and bridge engineers engaged in its research, now it is lack of researches on theory and mechanical performance of the key-value part, which is the woven timber arch structure composed of two systems. Therefore, taking Xi’nan bridge as the prototype, polymethyl methacrylate reduced scale model of Xi’nan bridge was made, then load tests of reduced scale model were carried out, deformation rule and distribution of internal force in woven timber arch under each kind of load were analyzed, the structure behavior research on woven timber arch of Min-zhe timber arch bridge was conducted. The main contents and research conclusions are as follows:(1) The structural size of Xi’nan bridge was measured on-site by manual mapping tool and total station, and the engineering drawings of Xi’nan bridge was drew. The width of Xi’nan bridge is 5m, the clear span is 15.33m, the clear rise is 3.55m, and the rise to span ratio is 1/4.3.(2) Reduced scale model of Xi’nan bridge was fabricated with a ratio of 1/6.14, and static load tests under symmetrical load and asymmetric load on naked arch model and total bridge model were carried out. The experimental results demonstrate that, under symmetrical load, the deformation of main arch is symmetric, the flat rib of the first system and the top cross beam of the second system are slip-off; Under asymmetrical load, the deformation of main arch is anti-symmetric, the flat rib of the first system and the top cross beam of the second system at the symmetrical side of load are slip-off.(3) The finite element program MIDAS/CIVIL was adopted for establishing and analyzing reduced scale model of Xi’nan bridge. The results show that, the finite element analysis results agree well with the testing results. Woven timber arch structure is given priority to the first system, and the second system attaches to the first system to limit the deformation of the first system and shares part of the internal force. The deformation of main arch structure under asymmetric load is bigger than the one under symmetric load, so the design of woven timber arch structure is controlled by asymmetric load. Both vertical displacement and longitudinal displacement of main arch are produced when Min-zhe timber arch bridge is under load case. The research results show that. The vertical displacement of main arch should be the design reference of Min-zhe woven timber arch bridge, longitudinal displacement and stress of key cross-section should be checked at the same time. The comparison results on deflection and internal force of naked arch model and total bridge model show that, spandrel construction takes part in resisting outside load and restrains the deflection of woven timber arch structure, which makes the internal force redistributed and the woven timber arch more stable.(4) Min-zhe timber arch bridge are calculated with the simplified plane model that analogizes from the plane simplified model of Bianhe Rainbow Bridge, The calculation results show that simplified calculation results of Min-zhe timber arch bridge are different from the real result, so the plane simplified model of Min-zhe timber arch bridge can’t be analogized from the plane simplified model of Bianhe Rainbow Bridge.