Study On Bearing Capacity And Design Method Of CFST Double-layer Shoulder Beam

The design of the concrete-filled steel tube(CFST)double-layer shoulder beam in industrial plants has always been focused by the structural designers widely.It is located between the upper column and the lower column.The double-layer shoulder beam can transfer the internal force of the upper column to the lower column and can be used as the support of crane beam.The research of the double-layer shoulder beam is behind the engineering application at present.Thereforce,this paper makes a deep research on the concrete-filled steel tube double-layer shoulder beam.Firstly,the rationality and validity of the finite element model is verified by the existing single-layer beam text by finite element software ANSYS.On the basis,the finite element analysis model of the concrete-filled steel tube double-layer shoulder beam is established.The model is used to discuss the unfavorable load of the double-layer shoulder beam and the failure mechanism of the double-layer shoulder beam is analyzed under the unfavorable load condition.The stress distribution,failure process and failure mode of the double-layer shoulder beam are investigated.The results show that the double-layer shoulder beam is damaged because of the buckling failure of the web of the upper shoulder-beam when the upper load and the lower load towards high side crane beam and the double-layer shoulder beam is damaged because of the buckling failure of the web of the lower shoulder-beam when the upper load and the lower load towards low side crane beam.Secondly,in order to put forward the design method of the double-layer shoulder beam,the influence factors of the bearing capacity of the double-layer shoulder beam are studied on the basis of the two failure modes.The results obtained indicate that,when the upper shoulder-beam is the main bearing part,the lower load,the height-span of upper shoulder-beam,the web thickness ratio of upper shoulder beam,the height of upper load,the height of lower load and the height of inner column have significant influence on the bearing capacity of double-layer shoulder beam.When the lower shoulder-beam is the main bearing part,the height of upper load,the height of lower load,the height of inner column,the height-span of lower shoulder-beam and the web thickness ratio of lower shoulder beam have significant effect on the bearing capacity of double-layer shoulder beam,and the effect of the height-span of upper shoulder-beam and the web thickness ratio of upper shoulder beam are not significant.Finally,on the basis of the design method of the single-layer shoulder beam,this paper focues on the calculation model and the load value of the double-layer shoulder beam.For the upper shouler beam,the lower load effective coefficient is put forward in order to consider the impact of lower load.Through the analysis of key factors influencing the effective coefficient,the formula of the effective coefficient is obtained.According to the effective coefficient,the calculation formula of upper load correction value is put forward.Then,the upper shoulder beam can be calculated according to the model of single-layer side column shoulder beam.For the lower shoulder beam,because the load is located above the cross section of the lower shoulder beam,it is not necessary to modify the load.Then,the lower shoulder beam can be calculated according to the model of single-layer side column shoulder beam.It is proved that the calculation formula of effective coefficient and the design method of double-layer shoulder beam are reasonable.