Modular girder system with easily variable cross-sections and construction method thereof

Soundproof tunnel girder with variable cross-sections using prefabricated steel pipe flanges and grout-connected webs

This technology is a modular girder system with variable cross-sections. It assembles composite girders spanning between roadside supports by combining prefabricated steel pipe upper and lower flanges with a web structure consisting of upper and lower members and a web plate.

I-beam and H-beam girders used for urban soundproof tunnel roofs are heavy, obstruct driver visibility, and have poor wind load resistance and ventilation. Furthermore, they require a uniform cross-section based on maximum member force, preventing section optimization, and are difficult to install between opposing supports.

This technology integrates the web structure by filling the space between the flanges and the web with grout. Adhesion is enhanced by protrusions on the inner surfaces of the upper/lower members and outer surfaces of the flanges. Fillets on the web reduce stress concentration at pipe joints, while ring stiffeners, threaded rods, and bolts reinforce the ends. Designers can select different pipe and web sizes for each section. Applicable to urban highway soundproof tunnels, elevated road noise barriers, and pedestrian decks, it uses standard KS steel pipes to reduce costs while allowing customized designs that increase cross-sections only where loads are high.

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Key Features:

• A flange section comprising an upper flange positioned at the top between supports and a lower flange spaced below it, arranged in segments laterally
• A web structure where a web plate is joined between an upper member inserted over the upper flange and a lower member inserted over the lower flange
• Grout filled into the space between the flange section and the web structure, which is coupled to at least one of the connected or non-connected parts of the flanges
• Protrusions formed on at least one of the inner surfaces of the upper and lower members or the outer surfaces of the flanges where the grout is filled

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This invention was developed with support from the Ministry of Land, Infrastructure and Transport for the development of a new lightweight soundproof tunnel structural system for four-lane roads.

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