English：

In industrial building construction, the scenario of installing equipment prior to roofconstruction is frequently encountered. When the roof is a concrete structure, the pre⁃installed equipmentoccupies the space required for support systems, posing significant challenges to the design andconstruction of the subsequent concrete formwork support system. Focusing on a water plant project inJinan, this study addresses the working condition where roof slabs are not cast yet but equipment isinstalling already, by designing a gantry support system spanning over the existing equipment. Z⁃shapedrosette⁃type scaffold is employed in the support system, with I18 steel joists placed in the U⁃shaped jacksat the top of the vertical members, secured on both sides with wooden wedges. Above these joists, a steelplatform spanning over the equipment is installed, utilizing I20B steel sections for the 6⁃meter span andI32C steel sections for the 9⁃meter span. Distribution beams are laid on the platform to facilitate theerection of the support system for the roof concrete structure. A three⁃dimensional finite element model ofthe gantry platform was developed and numerically analyzed. The results demonstrate that the mechanicalperformance and overall structural stability of the gantry support system comply with standardrequirements. During the dismantling phase, a “ dual⁃chain⁃block coordinated lifting ” method wasemployed, utilizing top⁃mounted blocks for vertical hoisting and side⁃mounted blocks for horizontaltraction, enabling the safe removal of steel sections within confined spaces. The rosette⁃based gantrysupport system effectively resolves construction challenges associated with spanning existing equipment in limited indoor spaces.