Reconstruct and maintenance of 9m Bridge

GM Designs presents an exceptional reconstruction design for a 9-meter bridge, focusing on the integration of steel beams with existing concrete abutments. The existing abutment has undergone thorough inspection by GM Designs’ office, guaranteeing its suitability for the reconstruction project. The concrete abutments had a depth of approximately 1000mm and a width of 930mm.

To connect the steel beams with the concrete abutments, a 25mm thick solid steel plate is placed between them. The plate is carefully laid on the old concrete surface, and a 10mm thick levelling mortar with a strength of 60MPa is applied. The steel plate is then welded to the steel beam using a 12mm flat weld on both sides. Furthermore, the connection between the steel beams and concrete abutments is reinforced by four M24 galvanized threaded rods chemset with FIS SB Epoxy. These rods are embedded into the existing concrete abutment with a minimum depth of 300mm.

Along the width of the bridge, six H20 rods are inserted between the two steel beams. These rods are accompanied by R12 stirrups placed at 400mm centers. Vertically, 12D16 bars are installed to connect the existing concrete abutment with the newly poured concrete. The D16 bars are spaced at 400mm centers. In the newly poured concrete, D12 bars are inserted, overlapping with the D16 bars, and turned 90° at the top of the concrete. Two D12 bars are placed inside this configuration along the width of the bridge. This arrangement allows for movement of the concrete deck while maintaining structural integrity.

Before attaching any deck units to the steel beams, the beams are jacked at mid-span off the riverbed by approximately 15mm, if possible. Following the jacking process, the deck units are attached. Subsequently, dry pack non shrinkage additive grout is placed with limited water content. This grout is left to cure for 14 days before the props supporting the center of the steel beams are removed.

The deck units of the bridge are designed to withstand HN loading with a 0.85 reduction factor applied for lightly trafficked rural bridges. Additional inserts are incorporated into the precast deck units to accommodate handrails. Shear connectors are preplaced into the deck units for welding to the beam flange edges.

In summary, GM Designs presents an effective reconstruction design for a 9 meter bridge, showcasing their meticulous approach to integrating steel beams with existing concrete abutments. The design incorporates precise welding, reinforcement, and meticulous construction techniques to ensure the structural integrity, safety, and longevity of the bridge.