Study on the critical factors of the successful construction using the incremental launching method (ILM) for a steel cable-stayed bridge

The construction of steel-structure bridges is faster and less damaging to the environment than that of concrete bridges. However, the traditional scaffolding method often used to construct steel bridges fail to fully exploit these advantages. The incremental launching method (ILM) minimizes traffic disruption and working space during construction; therefore, this method is ideal for inaccessible sites or where construction interference must be minimized. Despite its benefits, ILM is primarily used for constructing concrete bridges; it has rarely been applied for constructing steel-structure bridges. This article explores the advantages and applicability of the ILM for constructing steel-structure cable-stayed bridges by considering the new Dazhu Bridge in Taoyuan, Taiwan, as a case study. This bridge spans a 110-m highway, and its design requirements prohibit the creation of piers on the highway or the disruption of highway traffic. We compared the performance of the ILM and scaffolding method for single-span cable-stayed bridges with a focus on structural models, usage specifications, and construction methods. The incremental launching of steel structures can considerably reduce traffic interference and construction time while improving construction quality and safety. This method combines techniques for concrete bridge superstructure construction, such as the precast segment method, ILM, and ASM.