| The replacement of corrugated steel web for the traditional flat web is an improvement of I-girder.I-girder with corrugated webs can greatly reduce the cost of beam manufacturing and the weight of superstructure,improve the efficiency of Prestressed Loading,and make up for the shortcomings of poor bending performance and easy fatigue failure of the traditional stiffener flat web.At present,many scholars have done a lot of research on the bending and torsional buckling of the traditional I-beam with flat web,but the lateral-torsional buckling with discrete torsional braces I-girder with corrugated webs has not been studied in depth.In this paper,the theoretical derivation and finite element simulation are used to do a series of work on lateral-torsional buckling with discrete torsional braces I-girder with corrugated webs,the main contents and achievements are as follows:(1)Combined with the non contribution of corrugated steel web to bending stiffness,the calculation methods of the moment of inertia,moment of inertia,shear modulus,reasonable wave height,exact position of torsion center and warping moment of inertia of corrugated steel web I-beam with any section are given.The results show that the moment of inertia of the warping presented in this paper is in good agreement with the finite element results;the section moment of inertia and shear modulus of I-girder with corrugated webs are smaller than that of the I-beam with the flat web,and the shear modulus decreases with the increase of the maximum wave height and the bending angle;the warping moment of inertia of I-girder with corrugated webs is large It is found in the flat web,and increases with the increase of the maximum wave height and the angle of the wave.(2)Based on the verified section characteristics,the energy method is used to derive the calculation formula of the lateral torsional buckling strength of I-girder with symmetrical section corrugated steel webs under uniform bending moment.Its correctness is verified by the finite element value and the existing literature value.The thickness of corrugated steel webs,the type of corrugated steel webs,the calculated span and the height span ratio of corrugated steel webs are analyzed The impact of the..The lateral-torsional buckling strength of I-girder with corrugated webs under the action of unequal end bending moment,uniform load and concentrated load is studied.The influence of end moment ratio and torsion slenderness ratio on lateral-torsional buckling strength is analyzed.The results show that increasing the number of torsional braces can significantly improve the total stiffness requirements of structure and lateral-torsional buckling strength of full support beam;I-girder with corrugated webs lateral-torsional buckling strength is less affected by corrugated steel web thickness;it is affected by corrugated steel web model,calculated span,high span ratio,torsion length and slenderness The lateral-torsional buckling strength of I-girder with corrugated webs increases with the increase of end moment ratio.The stiffness requirements under uniform bending moment can be used to calculate the stiffness requirements of unequal end bending moment conservatively.(3)Based on the verified section characteristics,the calculation formula of Lateral-torsional buckling strength of I-girder with corrugated webs with asymmetric section under uniform bending moment is deduced by energy method.The correctness of the formula is verified by finite element method,and the influence of unequal end bending moment and asymmetry on lateral-torsional buckling strength is analyzed.The results show that the strength of lateral-torsional buckling increases first and then decreases with the increase of the end moment ratio of the unequal end bending moment,and increases with the increase of the asymmetry.The influence of the asymmetry on the strength of lateral-torsional buckling increases with the increase of Torsional braces number.The stiffness requirements under the uniform bending moment can be used to calculate the stiffness requirements under the action of unequal end bending moment.(4)Based on the existing research on elastic lateral-torsional buckling,according to the buckling curve recommended by the specification and the nonlinear finite element analysis,the non elastic lateral-torsional buckling strength of corrugated steel web I-shaped and fully supported beams is estimated and analyzed.The results show that the lateral-torsional buckling strength of I-girder with corrugated webs decreases due to the existence of initial defects,and the larger the initial defect,the lower the lateral-torsional buckling strength is,the less the whole supported I-girder with corrugated webs has no support I-beam,with an average decrease of about 30%;For both unsupported I-girder with corrugated webs and full support I-girder with corrugated webs,the defect coefficient 0.49 can be used to estimate lateral-torsional buckling strength;however,for both initial defects,the lateral-torsional buckling strength can be estimated conservatively by using the defect coefficient 0.76 recommended by the specification. |
