Research On Design Method Of The Capacity Of Arched Castellated Beam

The arch-shaped castellated beam has the advantages of both the solid web arch and the web opening beam,it can realize the stable bearing system with large span and save the cost of steel,and the hole is convenient for laying pipes and wires,and full of dynamic,its application is more and more extensive.However,when there is no lateral bracing or lateral bracing is insufficient,the beam will appears lateral buckling before in-plane buckling.At present,in the actual project,most rely on experience to layout the lateral bracing,and in the academic field,there is a little research on the lateral buckling of castellated arch,especially the effect of lateral support on its bearing capacity.In this paper,the castellated stability of circular arc-shaped castellated beams with lateral bracing and without lateral bracing will be researched.Four castellated arch members are designed to carry out the static loading test,at the same time,the FEM is simulated,and then will compare the results of both of them.By comparison,it is found that the results are close to each other,thus it is verified that the method of establishing finite element model is correct.Studied the lateral elastic buckling load of circular arc-shaped castellated girder without lateral bracing.By FEM,the buckling load under three kinds of vertical loads is obtained by eigenvalue buckling method,and combined with the range analysis in the orthogonal test method,to find out the influence rule of the various factors on the buckling load of the arch-shaped castellated beam and the order of influence degree,and then the optimal combination of factors under different load is given.The results show that the order of factors influencing is:rise-to-span ratio>web slenderness>diameter-depth Ratio.Under the same load,the arch castellated beam's buckling load of arch fixed at tow end is larger than pin-ended arch,and the effect of the three factors is more obvious.Studied the lateral elastic buckling load of the castellated beam with lateral bracing.Firstly,analyzed the beam with single bracing.Firstly,to study the influence rule of section position of the lateral bracing point,the lateral bracing stiffness and the rise-to-span ratio on the buckling load is.The results show that it is the most reasonable when the lateral bracing be placed on the upper flange,and then gives the critical stiffness when a single dome support.Then,the castellated arch with several equidistant lateral supports and the concentrated load of arch crown was studied.It is concluded that the buckling load of the castellated arch increases with the increase in the number of lateral supports(ie,the reduction of the lateral support spacing).And when the lateral support distance is 1/10 of the span of the arch,the critical stiffness of the lateral support is maximized.With the increase of the rise-to-span ratio,the critical stiffness of the equidistant lateral support decreases gradually,which indicates that the lateral support is more effective for the pin-ended arch under the concentrated crown load.Learn from the critical formula given in the "technical specifications for steel arch structure " that pin-ended and arc arch with biaxial symmetrical I-section no longer considered lateral buckling when full span horizontal uniform load.Considering the influence of the open hole in the web,the geometric slenderness ratio in the arch plane be converted into regularized slenderness ratio,receive the formulas when no longer consider the formula of out-of-plane stability of the arch after the open hole of the web under the same conditions are considered.