Study On Dynamic Performance Of PC Composite Grooved Beam With Corrugated Steel Webs

The trough-shaped beam with corrugated steel web(CSW)has become increasingly popular in urban elevated rail transit viaducts due to its aesthetic appearance,low structural height,and excellent noise reduction performance.However,traditional concrete trough-shaped beams have drawbacks such as complex load transfer paths,susceptibility to cracking in the web,and complicated reinforcement detailing.To further enhance the performance of traditional concrete trough-shaped beams,the research team proposed a novel bridge structure by replacing the traditional concrete web with a corrugated steel web to form a prestressed corrugated steel web precast concrete(PC)composite trough-shaped beam.This innovative bridge structure combines the advantages of prestressed concrete,corrugated steel web structure,and trough-shaped beam,making it better suited for the needs of urban rail transit,and exhibiting promising prospects for practical applications.In order to reveal the dynamic performance of the waveform steel webPC composite box girder and improve the design theory of this structure,this thesis comprehensively studies the free vibration characteristics and vehicle-induced vibration response of the waveform steel web-PC composite box girder through theoretical derivation,indoor experiments,numerical simulations,and combined simulation techniques.The main content and conclusions are as follows:(1)Considering the dual effects of shear deformation of the waveform steel web and shear lag of the composite girder,the governing differential equation for vertical free bending vibration of the waveform steel web-PC composite box girder is derived based on the energy method and Hamilton’s principle.The analytical formula for the natural frequencies of the simply supported composite box girder with waveform steel web,considering the dual effects of shear deformation and shear hysteresis,is obtained,and the correctness of the formula is verified through numerical examples.(2)A scaled test model beam of PC composite channel beam with corrugated steel webs was designed and manufactured for dynamic test and finite element linear perturbation analysis.The results show that after replacing the traditional concrete web with corrugated steel webs,the fundamental frequency changes less than 1 %,and the relative difference of the first five natural frequencies does not exceed 10 %.With the increase of the order,the difference of natural frequencies changes more and more.The first five modes of the two are the same,and the first 300 modes are mainly vertical and longitudinal bending.Through the comparative analysis of the test value,the finite element value and the calculated value of the highway bridge gauge,the correction formula of the fundamental frequency estimation formula of the simply supported beam of the highway bridge gauge is proposed based on the theoretical formula of this thesis,and the accuracy of the correction formula is verified.(3)Based on the numerical model,the influence of the size of the upper flange plate,the size of the bottom plate,the setting of the beam and the geometric elements of the corrugated steel web on the natural vibration characteristics of the PC composite channel beam with corrugated steel webs is discussed.The results show that changing the structural parameters,the width of the horizontal single plate of the corrugated steel web and the thickness of the web within a reasonable range will not affect the first 10 modes.Reducing the waveform angle of corrugated steel webs,increasing the horizontal veneer width of corrugated steel webs and increasing the web thickness of corrugated steel webs can increase the fundamental frequency;setting beams at three points between beams and setting the thickness of concrete slab reasonably can improve the torsional natural frequency,so as to improve the torsional stiffness.(4)A vehicle-bridge coupled vibration analysis is conducted by establishing a model of the waveform steel web-PC composite box girder and a type A vehicle of the subway.The study shows that when the train passes the bridge at speeds of 40-130km/h,the indicators such as mid-span deflection-to-span ratio,dynamic displacement,acceleration,vehicle derailment coefficient,wheel-rail lateral force,vehicle body acceleration,and Sperling index all meet the corresponding specification limits.The safety and stability,operational safety,and passenger comfort are good when the train passes the bridge at speeds not exceeding 70 km/h.Comparing the dynamic coefficient values calculated according to railway specifications of China,Europe,Japan,the United States,and Australia,it is found that the dynamic coefficient values calculated by European railway specifications are closer to those of China,and the applicability of the current Chinese specifications for calculating dynamic coefficient values is good for the waveform steel web-PC composite box girder.