The purpose of the middle hole in the truss of bailey bridge

The purpose of each hole of the truss of bailey bridge is as follows: when the string bolt hole is used for assembling the double deck or reinforced bridge, the truss bolt or the string bolt is inserted into the string bolt hole, so that the double deck truss or the truss is connected with the reinforced string rod; The support frame holes are used to install the support frame. When the truss is used as the main beam, the middle two holes are used; when the bridge foot, the end two holes are used to strengthen the connection between the two rows of trusses. The wind structure hole is used to connect the anti-wind tie rod; The support bracket hole on the end vertical rod for mounting the support bracket, diagonal brace and coupling plate; Beam jig hole is used for mounting beam jig. The lower chord is provided with four beam pads, on which bolts are fixed to limit the position of the beam. Each truss weighs 265 kilograms; 4 hands for shoulder lifting and 8 hands for hand lifting; If the reinforcing rod of the upper and lower chord is connected and then lifted by hand, 4 more people are needed. Install the beam in front of the vertical bar at the rear end of the second truss and clamp it with the beam clamp but do not tighten it. Install the diagonal bracing on the second beam and the wind-resistant pull rod of this truss, and assemble the external truss of the third section of the bridge. The windproof pull rod should not be tightened temporarily. Install the middle beam of section 2 and clamp it with the beam clamp. Install the support frame and tighten the wind-resistant tie bar and beam jig of the second section of the bridge. The following sections are assembled in the same procedure.