Research On Natural Vibration Characteristics Of Straight Composite Beam With Corrugated Steel Webs

This article relies on the Natural Science Foundation of Hebei Province,"Research on the bending and torsion mechanism of prestressed concrete composite beams with corrugated steel webs"(E2018210149),for corrugated steel webs with different cross sections of single box single room,single box double room,single box three room The composite beam adopts a combination of theoretical derivation,model test measurement and finite element software analysis to study its dynamic characteristics.The main work and research results are as follows:(1)Combining the dynamic principle with the energy variation principle and Hamilton principle,without considering the bending effect of the web,based on a comprehensive consideration of the shear strain energy of the corrugated steel web and the shear lag effect of the upper and lower flange plates,The correction of the shear modulus of the corrugated steel web is deduced from the vertical bending vibration pushed by the corrugated steel web combined simply supported beam,and the formula for calculating the bending vibration frequency of the simply supported box beam is obtained.(2)On the basis of considering the free torsional torque and constrained torsional torque of the box girder,based on the torsion theory of the closed section member,calculate the method of calculating the polar moment of inertia,torsion constant and fan moment of inertia related to the torsional vibration frequency,The energy method is used to derive the torsional vibration frequency of the composite beam with corrugated steel web to obtain the torsional vibration frequency control differential equation,and the general solution and special solution of the control differential equation are obtained according to the boundary conditions of the simply supported beam.Then the torsional vibration of the simply supported beam is derived.Calculation formula of frequency.(3)Design and manufacture model test beams of corrugated steel web composite beams,and perform experiments in the laboratory to measure the bending vibration frequency,torsional vibration frequency and mode shape of the model test beam.By comparing and analyzing the measured value with the theoretical calculation value,since the theoretical calculation is in the ideal state of the model test beam,there is inevitably a certain error between the two,so as to verify the correctness of the derived formula.(4)A finite element model of the test beam was established using ANSYS.The theoretical calculation results of the numerical results were compared with the experimental measured results,and the results were in good agreement.(5)The effects of parameters such as corrugated steel webs and diaphragms on the dynamic characteristics of the structure were studied using a finite element model.The parametric analysis show that the frequency of the vertical bending vibration of the structure gradually increases with the increase of the thickness of the web and the height-to-span ratio of the structure;it decreases gradually with the increase of the number of diaphragms,width-span ratio,and web wave angle;There was no significant change in the increase.The transverse bending vibration frequency first increases and then decreases with the thickness of the web and the aspect ratio;it decreases first and then increases with the increase of the corrugation angle of the steel web;it gradually decreases with the increase of the number of diaphragms;Gradually increase with the number of chambers.The torsional vibration frequency of the structure gradually increases with the increase of the web thickness,the number of diaphragms,and the number of boxes;it gradually decreases with the increase of the width-to-span ratio;it increases first and then decreases with the increase of the highspan ratio;With the increase of the corrugation angle of the web,it decreases first and then increases.