Model for Evaluation of Cast-in-place cantilever methods - considering safety cost progress

[[abstract]]台灣的地形，山區所佔比例很高，而都市土地之取得也日益困難。為減少對環境及生態之衝擊，及避免交通阻隔影響區域發展，公路建設採橋梁構築之比例大增。歷年來橋梁佔主線之比例已由中山高速公路的9%至北宜高速公路的54%。第二高速公路、西濱快速公路、東西向快速公路、高速鐵路、北宜高速公路等都大量引進先進的橋梁施工技術與設備，橋梁工程可謂是蓬勃發展，同時累積了可觀的經驗與大幅提高了施工成效。就橋梁工程上部構造而言，於北二高時期引進而加以推廣的場鑄節塊懸臂工法是一個典型的例子。 本研究探討國內場鑄節塊懸臂工法可能選用之工作車型式，旨在建構方案評估模式。先透過相關文獻之回顧，提出懸臂工法工作車評估架構，以「安全」、「成本」、「進度」三個構面下之「系統操控性」、「構架穩定性」、「施工可靠性」、「初置成本」、「操作成本」、「施工循環週期」、「閉合節塊施工時間」為評估因子，再運用層級分析法(AHP)，產生各因子之權重及各工作車型式之評分。其次，以橋長1000m、橋寬16m及最大跨距150 m之節塊箱梁橋設計為案例條件，驗證評估模式，並獲得三種工作車種型式之整體評分，懸吊桁架：0.1270、三角形桁架：0.4407、及菱形桁架：0.4323。本模式可作為營造商評估及選擇場鑄節塊懸臂工法工作車方案時之參考。[[abstract]]The terrain of Taiwan is characterized by a very high percentage of mountain areas, while lands in urban areas have become increasingly difficult for acquisition. To reduce the impact on the environment and ecological systems and to prevent traffic problems from affecting regional development, road projects have adopted a much greater share of bridge construction. Over the years, the proportion of bridges in the length of a main route has increased to 54% for Taipei-Ilan freeway from 9% for North-South freeway. A number of advanced bridge construction methods and systems have been introduced to projects such as the Second freeway, West Coast expressway, East-West expressway, Taiwan High Speed rail, and Taipei-Ilan freeway, rapidly advancing bridge engineering, while accumulating considerable experience and raising construction efficiency. In terms of construction of bridge upper structure, the cast-in-place cantilever method introduced during the Second freeway project for wider use is a successful example. This study investigated the false-work systems for the cast-in-place cantilever methods that may be selected for use in Taiwan, with the objective of developing a model for evaluation of possible options. Through a review of related works in the literature, an evaluation framework for the false-work systems was first proposed, which consists of seven factors: system controllability, structural stability, construction reliability, initial cost, operating cost, construction cycle time, and closing segment construction time that are categorized into three aspects: safety, cost, and progress. The analytic hierarchy process (AHP) method was used to produce the weights of the factors and the score of each false-work system. Next, the design of a segmental box-girder bridge with a length of 1000m, width of 16m, and largest span of 150m was used as case conditions for verification of the model, obtaining the overall scores for three false-work systems: suspension truss, triangular truss, and diamond truss at 0.1270, 0.4407, and 0.4323, respectively. Contractors may use the model as a decision aid in evaluating and selecting the false-work systems for the cast-in-place cantilever method