1. Determine the direction: According to the layout of the building, combined with the setting of air-conditioning pipelines and gas pipelines, convenient maintenance, and the density of cable routing to determine the best route of cable bridge. In the interior, as far as possible along the walls, columns, beams and floor slabs of the building, when using the comprehensive pipeline gallery to erect, it should be parallel on one side or above the pipeline, and consider the lead line and branch line as far as possible to avoid crossing, if there is no other pipe rack to borrow, it is necessary to set up (support) pillars.
2. Load calculation: Calculate the weight of the cable per unit length on the longitudinal section of the main trunk line of the cable bridge.
3. Determine the width of the bridge: determine the type and specification of the cable bridge, the length of the bracket, the length and spacing of the pillars, the width and the number of layers of the bridge according to the number of discharge cables, cable diameter and cable spacing.
4. Determine the installation mode: determine the fixing mode of the bridge frame according to the setting conditions of the place, choose suspension type, vertical type, side wall type or hybrid type, the connectors and fasteners are generally supplied with a complete set, and select the corresponding cover according to the structure of the bridge frame.
5. Draw the plane and section of cable bridge, and the space map and material table should also be drawn in part.
Selection Requirements of Cable Bridge Frame
When the length of steel straight section exceeds 30m and the length of aluminium alloy cable tray exceeds 15m, or when the FRP cable tray passes through the expansion (settlement) joint of the building, the O-30mm compensation margin should be left. The expansion connection plate should be adopted.
The selection of cable ladder, tray width and height should meet the requirements of filling rate. Generally, the filling rate of FRP cable bridge in ladder and tray is 40% - 50% for power cable and 50% for control cable. 70%, and it is advisable to reserve l0% to 252 project development margin.
When choosing the load grade of FRP cable bridge, the working uniform load of the cable bridge should not be greater than the rated uniform load of the load grade of the selected cable bridge. If the actual span of the suspension of the cable bridge is not equal to 2 m, the working uniform load should meet the following requirements: middle qG - - working uniform load, kN/m; qE - - rated uniform load, kN/m; LG - - actual span, M.
When the rated uniform load grade of the bridge needs to shield the cable lines from electromagnetic interference, or when there are environmental requirements such as outdoor sunshine, oil, corrosive liquids, flammable dust, etc. to protect the external shadow, the non-hole tray type FRP cable bridge should be selected.
In places where dust is easy to accumulate, cover plate should be used for FRP cable tray; in public passage or outdoor crossing road section, pad plate or holeless tray should be added to bottom bridge tray.