Support Topics

Support Topics / Engineer's Studio(R) Creation of the initial state of the cable structure

Purpose

When the model using the cable element is created, it is necessary to input the tension of the cable element. However, the tension of the cable might be uncertain before it's analyzed. Then,let us introduce the function to decide the cable tension of the initial state to the program.

Input Item

Let's consider the model of the suspension bridge like Figure 1 as an example. This model is a sample "SuspensionBridge.es" attached in Engineer's Studio(R). The tension shown in Figure 2 is given as an input of the cable element, 100kN is provisionally given before it analyzes it. This 100kN is an initial value of the convergent calculation. When 0kN is given, because the cable element is not approved as an element (It becomes irregular.), some tensions are given as an initial value. The costraint condition of the node is given in Figure 3. The costraint condition of 0.0mm is given to the row of Δ so as not to displace the node at the floor slab position in a perpendicular direction. Moreover, "Dead-load (St.)" is specified for the load case of the initial state. When the lateral calculation button is pushed, the load case is loaded to the model, the tension of the cable element and the section force of each material are calculated under the condition that the node at the floor slab position is not displaced. Tension of cable element calculated automatically is displayed as an element in the row of TX-i、TY-i、TZ-i、TX-j、TY-j、 TZ-j shown in Figure 4. The curve length of the cable element by the tension provisionally given is displayed in the row of "Length", and the curve length of the cable element calculated by an automatic calculation is displayed in the row of "Length of the initial state". A latter tension is an important result. Figure1　Sample model of the suspension bridge Figure2　Tension provisionally given to cable element Figure3　Input the constraint condition of node Figure4 Tension component of the cable element calculated automatically

Result

Figure 5 is a bending moment diagram of the initial state. This is a result of the analysis by adding the dummy load case (one that load value is not set, and only load case name was given) to the sequence load only by one step. As a result, the result of the initial state calculated automatically can be confirmed. The appearance to which the bending moment of the floor slab is distributed like a continuous beam in a multi span can be seen from the Figure. Figure5　Distribution of bending moment of the initial state

Supplement

Figure 6 is a deformation diagram at the time when the analysis is started from the initial state decided automatically and the seismic waveform is given. This figure is a deformation diagram that is enlarged about 430 times. The appearance to which the cable element vibrate can be seen from the diagram. Figure6　deformation diagram at the time of dynamic analysis（x430）

List

(Up&Coming 2012, Spring Issue)