Damage Mechanism and Calculation Method for Double-column RC Bridge Piers Subjected to Truck Impact
To study the damage mechanism and damage mode of double-column RC piers impacted by trucks,and to provide computational methods for the design of piers to resist collision,the power analysis software LS-DYNA was used to establish a refined finite element model of double-column RC piers impacted by trucks.Additionally,a simplified mass model of frame piers is used to replace the entire bridge model,a simplified model of the three-impulse load is introduced as a loading mechanism,and the finite element model and numerical algorithms are validated.The effectiveness of the finite element model and numerical algorithm is verified.The load-structure response analysis of double-column RC piers is performed by taking into account(among others)the influence of the truck model,vehicle weight,vehicular speed,and pier size.The entire process of damage and destruction of the piers under the impact of trucks is obtained,and the detailed evolution paths from the generation of bending cracks and the development of bending-shear cracks to shear destruction are revealed.The damage mechanism of double-column RC abutment impacted by trucks is clarified,and the dynamic response of the abutment is affected by both the stress wave propagation and inertia,and the maximum shear force and bending moment of the impacted abutment cross-section appear before and after the moment when the impact load reaches the peak value.Under different working conditions,the damage mode of the pier and the internal force response of the cross-section were analyzed,and the damage mode of the double-column RC pier was divided into three basic types:bending damage,shear damage,and complete collapse.The results obtained using the proposed truck impact double-column RC abutment dynamic shear capacity calculation method,and dynamic shear force and dynamic bending moment calculation method of the abutment cross-section show that the dynamic shear capacity of the abutment and the tensile strength of the concrete are directly proportional to the squared diameter of the abutment cross-section.The overall fit between the calculated internal force and the finite element simulation values in the cross-sections of the impacted piers is more than 95％,which can be used for the impact-resistant design calculation of double-column RC piers.
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