Study On The Force Analysis And Prevention Measures For The Old Arch Bridge Under Vehicle Jumping Based On The LS-DYNA

With the historical process of continuous development of bridge, arch bridge has been built countless, there is now Xu many much has been in operation for over the decades long, and traffic increasing the amount, the arch bridge overload use produces large and small damage, concrete loss occurs, uneven settlement and make the deck becomes uneven, driving in jumped in, increase the vehicle bridge coupling, which not only affects the driving comfort and safety, but also to promote the vibration of the arch bridge strengthening structure. Therefore, it is very necessary to research on the bridge deck of the arch bridge, this paper carries on the dynamic simulation analysis of the bridge deck by the dynamic nonlinear software LS-DNYA:Firstly. simple introduces the usage of the main software HyperMesh and LS-DYNA, and the establishment of a single span of 50m bearing arch bridge and ordinary loading truck finite element model, through modal analysis of arch bridge model, obtained the self vibration frequency.Secondly, the vehicle on the bridge deck were dynamic simulation, a smooth, sinusoidal, cosine distribution and discrete distribution of four bridge model, contrast four uneven arch bridge dynamic response of bridge condition, through comparison of girder and arch vertical acceleration time history curve, preliminary obtained Sino Vietnamese irregular driving deck arch bridge vibration more strongly point caused by.Thirdly. the flat deck condition and is provided with five barrier unit jump car deck condition contrast, in driving the process of full bridge, compared to jump out of the vehicle and smooth occurs when the deflection, vertical acceleration, force and interfacial force, it is inferred that the jump car has enhanced the arch bridge dynamic response, which belongs to the unsafe state.Fourthly, through the simulation of vehicle jumping under the control of several different factors, mainly considering the transverse and longitudinal arch bridge bridge to different locations, bridge barriers height and weight, speed factors, through the LS-DYNA software in each factor to establish 3-5 conditions were analyzed, and the obtained from the deflection curve should force, vertical acceleration and energy. From the change of form and peak size, inferred jumping occurs when the various factors that influence the dynamic response of the arch bridge, near the cross bridge to jump on both sides compared to the intermediate vehicle jump caused by girder bottom stress concentration, easy to cause cracking; the higher barrier, jumped out of the car after the girder and arch deflection, the greater the stress vibration, more intense; speed up, produce stress and deflection will increase, while the acceleration and the vibration energy of the vertical structure is larger, the vibration of arch bridge strengthening; the greater the weight, after jumping The greater the deflection, the stress in the tensile zone, the greater the vibration energy and the vertical acceleration, the stronger the vibration of the arch bridge.Fifthly. extraction in each group operating conditions of tensile stress peak, according to the changing tendency and with material allowable tensile force as the standard calculated the critical value of a security, while referring to the driving comfort, the relatively effective prevention and control measures.