Lattice and Profile Girders

Lattice and Profile Girders

Steel ribs: NPI, NPU, HEA and HEB sections are bent to the tunnel profile and fitted with welded connection plates. They carry load as soon as they are installed, so they are preferred in heavy and squeezing ground, at portals and where face instability is a risk. Lattice girders: Three-dimensional frames of longitudinal bars joined by diagonal members. Lighter and easier to handle than steel ribs, they let shotcrete fill in and around the girder without voids, so the girder and shotcrete act together. Both types are bent on jigs in our plant, with section geometry, flange positions, bolt holes and weld details checked. Every segment is marked with a project and part code (e.g. T7 M2) before shipment, so the erection sequence on site is clear. On-site fabrication is available on request where conditions allow.