基樁耐震性能分析之初探

Study on Performance-Based Earthquake Engineering for Pile Foundations

楊子逸(Tzu-Yi Yang)

指導教授 ： 張德文

淡江大學/工學院/土木工程學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00101

摘要

本研究嘗試以地震工程性能分析概念評估基樁耐震性能。地工構造物之地震工程性能分析須考量地震、土壤參數、地質構造等變化所可能產生之影響，其評估參數可包括：量測震度、工程需求參數、破壞計量和決策變數。對樁基而言，吾人可依據地震災害機率分析逐項分析上述參數之年超越機率，並依據美國太平洋地震工程研究中心所建議之Framing Equation程序分析特定樁基礎的耐震性能，以滿足設計須求。本研究藉EQWEAP程式探討台北、台中、高雄與宜蘭等四個台灣主要都會區之特定樁基耐震性能，並以近年影響四地之代表性地震為主，藉由各地的地震危害度曲線配合耐震設計規範之中度、設計和最大考量地震所對應的地表最大加速度，並以各地具相似地盤構造的測站紀錄為主進行地震模擬，推求不同地震等級之樁基反應，並以樁頂最大位移為工程需求參數，嘗試建立各地特定樁之不同耐震性能所對應的樁頂位移以及設計參數之影響。
研究結果顯示： (1)台北、台中、高雄與宜蘭四地區之樁基位移危害度結果均有不同，其中宜蘭最高，而台中最小，此結果主要受地層及地震危害度之影響；(2)當改變樁徑、彈性模數、SPT-N與孔隙水壓模式皆會影響樁基位移情形，考量性能設計後影響不如預期，表示性能設計與傳統設計可能有不同結果；(3不同工址的樁基反應明顯不同，除地震因素外，工址地盤較堅硬者，其樁基反應危害小；地盤土層厚度亦將影響結果，分析須視個案而行，同時須檢視破壞計量，以窺全貌；(4) EQWEAP分析程式與PHSA流程相輔使用，確實可得各地之樁基位移危害度曲線。進一步研究可就土壤-樁帽-樁基的互制、材料模式、土壤參數影響等事項加以改善並討論。

關鍵字

樁基礎 ； 耐震性能 ； 地震災害機率分析 ； 危害度曲線 ； 需求曲線 ； PSHA ； EQWEAP

並列摘要

This study intends to estimate the seismic performance of piles based on PBEE analysis. The PBEE analysis for geotechnical structures requires the concerns of varying earthquake, soil parameters and geology conditions. It is not only for design purpose, but also for decision making. The valuable parameters can include IM, EDP, DM and DV. One can analyze the probability of annual exceedance for these parameters from PSHA, and discuss the performance of a specific pile foundation based on PEER Framing Equation. This study adopts EQWEAP module to study the seismic performance of a specific pile at four major cities in Taiwan. With the recent representative earthquakes affecting four cities, the medium and design as well as the most concern earthquakes were studied for a certain single pile located in a typical soil profile. The largest pile displacements, selected as EDP , were examined whereas the possible failures were recorded. The maximum pile displacements at different performance levels in these metropolitans were obtained and analyzed to achieve the relationships of the annual rate exceedance and the maxim pile displacements. The influences of the esign factors were discussed. The observation are summarized as follows: (1) The pile displacement hazard in Taichung is the smallest, whereas Yilan has the highest, this is significantly dependent of the seismicity and geological conditions of the site. (2) Enhance the design by increasing the pile diameter and so for may reduce the pile displacement, however the influence in the response hazard curve may not that significant. This reveals clearly the resulting difference between deterministic design and probabilistic design. (3) The seismic hazard of the pile response is dependent of the site conditions, not only the ground stiffness but also the depth of bedrock will affect the results. The analysis must be at project level, and the damage measure of the pile should be taken into account. (4) The EQWEAP analysis is compiled well with the PSHA in this case. Modification of the work can be done with the concerns of soil-cap-pile interactions, material models and the influences of the soil parameters.

並列關鍵字

pile foundation ； analyze the probability of annual exceedance ； seismic performance ； hazard curve ； demand curve ； PSHA ； EQWEAP

參考文獻

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