What should be noted about the suitability of steel bridge truss elements for connection using string rods

The steel bridge truss element is welded by upper and lower chord rods, vertical rods and diagonal braces. One end of the upper and lower strings is a negative head, and the other end is a positive head. There are pin holes on the negative and positive heads. When two truss splicing, insert the male head of one section into the negative head of another section, align the pin hole, insert the pin. The purpose of each hole of the truss is as follows: when the string bolt hole is used for assembling double deck or reinforcing steel bridge, the truss bolt or string bolt is inserted into the string bolt hole, so that the double deck truss or truss is connected with the reinforcing string; The support frame hole is used to install the support frame, when the truss is used as the main beam, with the middle two holes, as the bridge foot, with the end of the two holes, to strengthen the connection between the two rows of trusses; The wind hole is used to connect the wind resistance rod; The support frame hole on the end vertical rod is used for installing the support frame, slanting support and connecting plate; Beam fixture hole is used to install beam fixture. The lower chord is provided with 4 crossbeam gasket plates, and the gasket plate is provided with a bolt nail to define the position of the crossbeam.