受沖刷橋梁可靠度設計方法研究

Study on the Reliability-based Design Method for Scoured Bridges

劉俊仁(Chun-Jen Liu)

指導教授 ： 張國鎮

國立臺灣大學/工學院/土木工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.02295

摘要

對於跨河橋梁而言在各種造成橋梁發生破壞之原因中，國內外研究均指出沖刷現象為主要原因之一。而現有的橋梁設計規範中，尚未以載重型式針對沖刷效應進行適當設計考量，若考量多重災害之可靠度設計，應用載重抗力係數設計法時將產生設計載重型式不一致之困擾。本研究應用創新思維，將沖刷效應轉換為等值載重之形式，並將等值載重放入載重組合後，得到直接之設計方法。
本研究接續團隊歷年研究成果，由等效沖刷載重模式出發。將此等效沖刷作用載重模式應用至沖刷易損性曲線之建置及多重災害之載重抗力係數設計法中，盼能在考量沖刷事件之橋梁評估及設計提供幫助。以蒙地卡羅法進行亂數分析，配合條件機率計算橋梁破壞機率以建置沖刷易損性曲線；而多重災害之載重抗力係數設計法則以可靠度分析來完成。
建置出沖刷易損性曲線後，工程師可由沖刷易損性曲線迅速判斷橋梁沖刷深度所對應到的破壞機率。而多重災害之載重抗力係數設計法之載重係數，則使用在跨河橋梁設計上，以求合乎可靠度分析邏輯之設計流程。

關鍵字

橋梁沖刷 ； 等效沖刷作用載重 ； 沖刷易損性曲線 ； 多重災害之載重抗力係數設計法

並列摘要

There are many reasons that make crossing bridge failure, Domestic and international studies have pointed out that one of the main reasons is scour event. In the existing bridge design codes, the scour effect is not considered as a load effect. When considering multiple-hazard reliability design, engineers will face the problem with load and resistance factor design which didn't consider scour effect as a load. This study offer a creative thinking that transfer the scour effect into load pattern and put in load combinations, obtain a more direct method of design.
The research team continues the previous results, start from the concept of equivalent scour load. We purposed two applications of equivalent scour load, one is build the scour fragility curve, the other is calculate the load factors of multiple-hazard load and resistance factor design. The objective is to help engineers to evaluate and design crossing bridge with scour event. Using Monte Carlo method to simulate hazard, and evaluate the bridge failure probability with the conditional probability. Finally we can get scour fragility curve. To calculate the load factors in multiple-hazard load and resistance factor design by reliability analysis.
After develop scour fragility curve, engineers can quickly obtain the failure probability by scour depth. The load factor of multiple-hazard load and resistance factor design will be used in design crossing bridge, which make design procedure smoother.

並列關鍵字

Bridge scour ； Equivalent scour load ； Scour fragility curve ； Multi hazard-LRFD

參考文獻

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