Analysis On Truss With Rotary Dish-type Fastener In Silo

The silo is widely used due to its high capacity and convenience.The storage of the silo is increasing with the economic development.The diameter of the silo is enlarged constantly and the diameter of the construction is larger,which increases difficulties to the design and construction of the truss.While there is little research on the silo construction platform and few construction experience can be referenced at present.Therefore,it is necessary to research the silo construction platform in detail..A new type of truss with rotary dish-type fastener is researched in this paper.The new truss is erected by steel pipes and converts the traditionally vertical support system to the horizontal support system.The safety and security of workers are enhanced.The construction period is shorted with lower cost.The resource is saved because the truss could be used repeatedly.Nonlinear analysis of the whole process is proceed to study the ultimate bearing capacity of the truss in diameter of 30 meters.The finite element analysis is carried out on the truss with two circles of cables and with three circles of cables respectively.The ultimate load of the two kinds of truss is 6300 kN and 12300 kN.The safety of truss is quantificated by the security reserve index of bearing capacity and deflection.It is indicated that the security reserve of the two kinds of truss is bigger than one.And the security coefficient is smaller than the limit.So the security reserve of truss with new rotary dish-type is sufficient.According to the mechanical analysis on the truss in diameter of 30 meters,the truss is reinforced by four different schemes.Through the comparative analysis on truss stiffness(namely the maximum deflection)and total steel quantity(namely the weight)of strengthened truss,the most economical and reasonable reinforcement scheme is the double layer truss in the center of 3 x 3.The deflection of reinforced truss compared with the one without strengthening reduces 28% in the second construction period and 33% in the third construction phase,while the weight increases just a little.It is revealed that the stiffness of truss is improved effectively by strengthening.Prestress is applied to the lower chord in order to reduce the deflection of the truss.The prestress cables are linked to the joint where the cables in inner circle anchorages to the truss.It is showed that the deflection decreases straightly by the increasing of prestress,and the stress of lower chords in the middle of the longest span decreases.Considering the stress limit and prestress loss,the tension control stress is 930 MPa.The deflection of the truss is 73 mm,which is 33% lower than that of the ordinary truss without prestress.It is indicated that the stiffness is increased effectively by prestress infliction.The ultimate bearing capacity of the prestress truss is 7100 kN,which is a little bigger than that of non prestress truss.