Numerical Simulation And Experimental Research On Cable-strut Joint In Prestressed Cable-stayed Column

The pre-stressed cables can provide lateral support for the middle column, which can reduce the calculating length to get a higher stability capacity of the pre-stressed cable-stayed column. As the cable-strut joint is one of the key parts of the cable-stayed column, study conducted on it is far insufficient.To study the friction and slippage in the cable-strut for the pre-stressed cable-stayed column with continuous and intermittent-continuous cable struts, experimental study and finite element method is conducted. In this paper, model with the orthotropic cables and model with line-surface contact element are brought up to simulate the cable-strut joints.And based on the pre-stressed cable-stayed column, cable force, equivalent friction force and slippage of each models are made comparison. The main studying work and responding conclusions are as follows:(1) Experimental study of pre-stressed cable-stayed column with continuous and intermittent-continuous cable-strut jointsPre-stress application stage and loads application stage experiments are conducted on the pre-stressed cable-stayed column with continuous and intermittent-continuous cable-strut joints. And displacement, strain and cable force are tested, relatively.In the pre-stress application stage, the cable forces of four cables of the two kinds of pre-stressed cable-stayed columns shows linearly increasing trend; slippage is caused in both of the two models. In the loads application stage, cable forces and stay stress shows linearly increasing trend and the column stress shows linearly decreasing trend. Under the same loads, the larger the pre-stress is, the smaller the slippage of the cables is; under the same loads increment, the smaller the pre-stress is, the more the increasing the slippage is.(2) Feasibility of model building method of the pre-stressed cable stayed columnOn the basis of the experimental study, finite models are built for continuous cable-strut joint and intermittent-continuous cable-strut joint. Analysis is conducted in pre-stress application stage and load application stage. Comparison is made between the simulation results and experimental results in terms of cable forces and stress to prove the element choice, contact definition and constraint types are correct. It is proved that application of beam188 and link10 and solid 185 element to simulate the stay and column,non-solid cable and the parts of the joint, relatively, is correct. Couple between the non-solid cable and solid cable, and that between the stay and cable-strut joint is feasible.In the pre-stress application stage and loads application stage, both the cable forces and stress of the middle columns for cable stayed column with continuous cable-strut joints and column with intermittent continuous cable-strut joints is consistent with the theory; the stress distribution of all parts of the joints is consistent with the theory.(3) Cable-strut Simulation method discussionOn the basis of modeling argumentation, new simulation methods of cable-strut joint is discussed. In this paper, orthotropic cable model and line-surface contact element model are applied. And cable forces, slippage and equivalent friction force and stress are made comparison among the different finite element models.Radial flexibility of model with surface-surface orthotropic cables is larger than that with surface-to-surface isotropic cables. Slippage of the former is larger than that of the latter. In this paper, slippage of the former is about 5 to 7 times larger than that of the latter.And the equivalent friction force of the former is larger than that of the latter. Simulation effect of the model with line-surface isotropic cables is relatively worse, and that of the model with line-surface orthotropic cables is relatively better. As a whole, simulation effect of model with surface-surface orthotropic cables is relatively better.(4)Analysis of stability capacityFormula of the stability capacity of the cable-stayed column with continuous cable-strut joints is derived. As a result, the theoretical system of the cable-stayed column become more perfect. Taking a cable-stayed column for example, comparison among the stability capacity of theoretical calculation, model with orthotropic cables, model with isotropic cables and model with discontinuous cables is made, which proves that model with orthotropic cables is a better simulation choice.