## 3 One-Time Closed Study  
The side-to-mid-span ratio of existing high-pier multispan continuous rigid bridges in China is generally between 0.5 and 0.6. The selection of side-and-center-span ratio in the cantilever construction of continuous rigid bridges is related to the method of construction of the side-span cast-in-place section. When the transition pier is high, the cast-in-situ section adopts the construction method of guide beam or hanger, and the length is generally 4-5 m, so the side-to-mid-span ratio is smaller [17]. When the transition pier is high, the construction method of using a guide beam or hanger is adopted, and the length is generally 4-5 m, so the ratio of the side center span is smaller. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Closed Method** & **Advantages** & **Disadvantages** & **Scope of Application** \\ \hline \multirow{4}{*}{Hanger (guide beam) closed} & The use of Berle type rod & The truss at the top of the side & \multirow{4}{*}{The edge across the straight-line segment must not be too long or too heavy.} \\  & manufacturing equipment & pier of the hanger needs to & \\  & and fine rolled rebar to make & bear a lot of shear force and & \\  & the boom, by which the & pressure, which is not & \\  & processing cost is reduced. & conducive to the stress of & \\  & The side-pier bias is small. & the truss. & \\ \hline \multirow{4}{*}{Bracket closed} & Widely used in construction, mature technology, less & The bracket needs to be & \multirow{4}{*}{It is not suitable for continuous rigid-frame} \\  & abutment bias pressure. & bracket is cumbersome. The & \\  & abutment bias pressure. & eccentric force of the junction & \\  & & pier requires the & \\  & & counterweight to be set at the & \\  & & approach bridge side. & \\ \hline \multirow{4}{*}{Hanging-basket closed} & The use of hanging baskets & Under the action of the hanging basket and the & \multirow{4}{*}{A continuous rigid-frame bridge with a small} \\  & after the completion of the & weight of the concrete across & \\  & cantilever end construction & the side of the T structure, & \\  & greatly shortens the & there will be a large deflection, & \\  & construction cycle and & which is not conducive to the & \\  & reduces the cost of the project. & stress of the structure. & \\ \hline \multirow{4}{*}{Floor-stand closed} & The construction method is & The construction period is & It is more suitable for the \\  & relatively simple, and the & long, and the risk coefficient & continuous rigid frame bridge \\  & requirements for construction & of setting up the landing & \\  & machinery and lifting & support is higher for the high & \\  & equipment are low. & pier or the water side terrain. & \\ \hline \multirow{4}{*}{Multimodal coordination of construction} & A variety of closure methods & \multirow{4}{*}{The amount of construction} & \multirow{4}{*}{
\begin{tabular}{} \end{tabular} } \\  & that facilitate construction and & & \\ \cline{1-1}  & reduce the impact of adverse & & \\ \cline{1-1}  & construction & load on the structure to ensure & \\ \cline{1-1}  & (floor rack + hanging basket, & the construction quality. For & \\ \cline{1-1}  & bracket + hanging basket, etc.) & the unconventional closure & construction cost. & \\ \cline{1-1}  & mode, we can ensure the & & \\ \cline{1-1}  & safety of construction. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparative analysis of advantages and disadvantages of different closing methods. For high-pier continuous rigid-frame bridges with small side and center spans, construction of the side spans is performed via the one-time casting and closed method, which is more beneficial than the conventional construction process in terms of construction period and economy [18]. The conventional process of construction of continuous rigid-frame bridge side spans and one-time joining construction are shown in Figures 5 and 6 below.