計畫資訊 NCREE-F2012001

Project Information / 計畫資訊

Project ID. / 計畫代碼	NCREE-F2012001
主持人	張國鎮
PI	Kuo-Chun Chang
單位	國震中心
Organization	NCREE
計畫名稱	牛鬥橋耐震能力現地試驗
Project Name	In-situ Seismic Performance Test at NiuDou Bridge
Project No. / 計畫編號
Keywords / 關鍵字
Begin Date / 計畫啟始	2012/1/1
End Date / 計畫結束	2012/12/31
Abstract / 摘要	本文探討牛鬥橋現地實驗中橋柱之耐震行為。橋柱實驗規劃包括P3橋墩標竿試體耐震實驗、P4橋墩基礎沖刷裸露耐震實驗、與P2橋墩設計地震擬動態實驗。實驗結果顯示，三根橋柱材料強度雖略有差異但整體行為十分接近，最大強度約100tonf，最大側位移角可達5%。P3橋柱破壞模式為撓曲破壞、P4及P2橋墩則為呈現撓剪破壞。經由擬動態實驗驗證，本橋在設計地震0.32g等級地震作用下尚屬安全，但因耐震設計細節無耐震彎鉤之設計，較無法提供有效的圍束效果，在大位移下產生主筋挫屈與橫向鋼筋搭接脫落現象。此外，本研究建議橋柱非線性分析模式，搭配SERCB for Bridge程式可有效掌握橋柱單向側推與反覆耐震行為，提供橋梁耐震能力詳細評估與補強作業之參考依據。
Abstract	This paper presents in-situ seismic performance tests of a bridge before its demolition due to accumulated scouring problem. The tests were conducted on three single columns and one caisson-type foundation. The three single columns were 1.8 m in diameter, reinforced by 30-D32 longitudinal reinforcements and laterally hooped by D16 reinforcements with spacing of 20 cm. The column height is 9.54 m, 10.59 m and 10.37 m for Column P2, P3, and P4, respectively. Column P2 had no exposed foundation and was subjected to pseudo-dynamic tests with peak ground acceleration of 0.32 g fi rst, followed by one cyclic loading test. Column P3 was the benchmark specimen with exposed length of 1.2 m on its foundation. The exposed length for Column P4 was excavated to 4 m, approximately 1/3 of the foundation length, to study the effect of the scouring problem to the column performance. Both Column P3 and Column P4 were subjected to cyclic loading tests. Based on the test results, due to the large dimension of the caisson foundation and the well graded gravel soil type that provided large lateral resistance, the seismic performance among the three columns had only minor differences. Lateral push tests were also conducted on the caisson foundation at Column P5. The caisson was 12 m long and had circular cross-sections whose diameters were 5 m in the upper portion and 4 m in the lower portion. An analytical model to simulate the test results was developed in the OpenSees platform. The analytical model comprised nonlinear fl exural elements as well as nonlinear soil springs. The analytical results closely followed the experimental test results. A parametric study to predict the behavior of the bridge column with different ground motions and different levels of scouring on the foundation are also discussed.

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Experiments / 實驗清單

實驗代號 Experiment ID	實驗名稱	Experiment Name	地點 Site	設施 Facility	實驗類型 Type	試體材料 Material	說明	Description
P2-C	牛鬥橋現地實驗-P2橋墩	In-Situ Test of Niu-Dou Bridge, Column P2	NCREE	Field	Cyclical loading test	RC	P2橋柱位屬河道高灘地區域，無基礎沖刷情況，規劃依84年耐震設計規範製作人造地震，先進行擬動態試驗後，再施加單一循環側推試驗。擬動態實驗輸入用之地震歷時記錄，考量橋址位於宜蘭縣，地震事件選用民國91年3月31日地震（規模6.8）於三星鄉牛鬥地區所紀錄之資料，強震站測站編碼為ILA025，震央距離84.2km。依據現行民國98年6月修訂之公路橋梁耐震設計規範，第二章之震區基本資料與第三章3.4.1節地震歷時之規定製作人造地震歷時。由於實驗時橋柱受力方向與測站所收錄之東-西、南北向歷時約呈45度夾角，故將原始紀錄之東西向與南北向地震歷時，依照45度夾角分量重新組合成一組新的地震歷時，再進行人造地震製作，命名為at-45deg。因原始紀錄時間較長，考量現場作業時間與系統穩定性，實驗中僅選擇主要震動區段40秒記錄作為輸入地表加速度。	This study employed a cyclic loading experiment as the primary test for Columns P3 and P4, and the loading protocol was conducted at drift ratios of 0.25%, 0.375%, 0.5%, 0.75%, 1.0%, 1.5%, 2.0%, and 3.0%. Two cycles were performed at each drift angle. Considering the limitations to the stroke of the actuator, cyclic loading was pulled to 3% drift before it was further pushed to a drift of 5%. Prior to the single-cycle pushover test, a pseudo-dynamic test was conducted on Column P2. An artifi cial time-history compatible with the design response spectrum according to the seismic design specifi cation for highway bridges (MOTC, 2009) was developed. Because the Niu-Dou Bridge was situated in Yilan County, the data pertaining to the earthquake event on March 31, 2002 (Richter scale of 6.8) in the Niu-Dou region of Sansing Township were used in this study. The design parameters were Ss D = 0.8 and S1 D = 0.45. The ground motion record was selected from station ILA025. In the experiment, the original time history for east-west (PGA = 90.74 Gal) and southnorth (PGA = 118.62 Gal) directions was assembled into a new ground acceleration. Subsequently, an artifi cial time history compatible with the design response spectrum was created. Considering the total duration of the original record was relatively long, and the time limitation of the on-site operation and system stability, only the main 40 s vibration record was adopted as the input ground acceleration for the experiment.
P2-PD	牛鬥橋現地實驗-P2橋墩	In-Situ Test of Niu-Dou Bridge, Column P2	NCREE	Field	Pseudo-dynamic test	RC	P2橋柱位屬河道高灘地區域，無基礎沖刷情況，規劃依84年耐震設計規範製作人造地震，先進行擬動態試驗後，再施加單一循環側推試驗。擬動態實驗輸入用之地震歷時記錄，考量橋址位於宜蘭縣，地震事件選用民國91年3月31日地震（規模6.8）於三星鄉牛鬥地區所紀錄之資料，強震站測站編碼為ILA025，震央距離84.2km。依據現行民國98年6月修訂之公路橋梁耐震設計規範，第二章之震區基本資料與第三章3.4.1節地震歷時之規定製作人造地震歷時。由於實驗時橋柱受力方向與測站所收錄之東-西、南北向歷時約呈45度夾角，故將原始紀錄之東西向與南北向地震歷時，依照45度夾角分量重新組合成一組新的地震歷時，再進行人造地震製作，命名為at-45deg。因原始紀錄時間較長，考量現場作業時間與系統穩定性，實驗中僅選擇主要震動區段40秒記錄作為輸入地表加速度。	This study employed a cyclic loading experiment as the primary test for Columns P3 and P4, and the loading protocol was conducted at drift ratios of 0.25%, 0.375%, 0.5%, 0.75%, 1.0%, 1.5%, 2.0%, and 3.0%. Two cycles were performed at each drift angle. Considering the limitations to the stroke of the actuator, cyclic loading was pulled to 3% drift before it was further pushed to a drift of 5%. Prior to the single-cycle pushover test, a pseudo-dynamic test was conducted on Column P2. An artifi cial time-history compatible with the design response spectrum according to the seismic design specifi cation for highway bridges (MOTC, 2009) was developed. Because the Niu-Dou Bridge was situated in Yilan County, the data pertaining to the earthquake event on March 31, 2002 (Richter scale of 6.8) in the Niu-Dou region of Sansing Township were used in this study. The design parameters were Ss D = 0.8 and S1 D = 0.45. The ground motion record was selected from station ILA025. In the experiment, the original time history for east-west (PGA = 90.74 Gal) and southnorth (PGA = 118.62 Gal) directions was assembled into a new ground acceleration. Subsequently, an artifi cial time history compatible with the design response spectrum was created. Considering the total duration of the original record was relatively long, and the time limitation of the on-site operation and system stability, only the main 40 s vibration record was adopted as the input ground acceleration for the experiment.
P3	牛鬥橋現地實驗-P3橋墩	In-Situ Test of Niu-Dou Bridge, Column P3	NCREE	Field	Cyclical loading test	RC	P3橋柱現況基礎裸露深度為1.2公尺，所受沖刷影響較為輕微，屬一般橋梁中為數較多的情況，故歸類為本試驗之標竿試體；P4橋柱現況基礎裸露深度為2.8公尺，為求確切反應沖刷對橋柱耐震能力的影響，並兼顧試驗的安全性，於基礎底部再額外開挖至總裸露深度為4公尺，即1/3沉箱深度，以做為本試驗之沖刷試體。而P3及P4橋柱將先各別進行反覆載重試驗至側位移比3%，再施以單向側推試驗至油壓制動器之最大衝程（約5%側移角）。	This study employed a cyclic loading experiment as the primary test for Columns P3 and P4, and the loading protocol was conducted at drift ratios of 0.25%, 0.375%, 0.5%, 0.75%, 1.0%, 1.5%, 2.0%, and 3.0%. Two cycles were performed at each drift angle. Considering the limitations to the stroke of the actuator, cyclic loading was pulled to 3% drift before it was further pushed to a drift of 5%. Prior to the single-cycle pushover test, a pseudo-dynamic test was conducted on Column P2. An artifi cial time-history compatible with the design response spectrum according to the seismic design specifi cation for highway bridges (MOTC, 2009) was developed. Because the Niu-Dou Bridge was situated in Yilan County, the data pertaining to the earthquake event on March 31, 2002 (Richter scale of 6.8) in the Niu-Dou region of Sansing Township were used in this study. The design parameters were Ss D = 0.8 and S1 D = 0.45. The ground motion record was selected from station ILA025. In the experiment, the original time history for east-west (PGA = 90.74 Gal) and southnorth (PGA = 118.62 Gal) directions was assembled into a new ground acceleration. Subsequently, an artifi cial time history compatible with the design response spectrum was created. Considering the total duration of the original record was relatively long, and the time limitation of the on-site operation and system stability, only the main 40 s vibration record was adopted as the input ground acceleration for the experiment.
P4	牛鬥橋現地實驗-P4橋墩	In-Situ Test of Niu-Dou Bridge, Column P4	NCREE	Field	Cyclical loading test	RC	P3橋柱現況基礎裸露深度為1.2公尺，所受沖刷影響較為輕微，屬一般橋梁中為數較多的情況，故歸類為本試驗之標竿試體；P4橋柱現況基礎裸露深度為2.8公尺，為求確切反應沖刷對橋柱耐震能力的影響，並兼顧試驗的安全性，於基礎底部再額外開挖至總裸露深度為4公尺，即1/3沉箱深度，以做為本試驗之沖刷試體。而P3及P4橋柱將先各別進行反覆載重試驗至側位移比3%，再施以單向側推試驗至油壓制動器之最大衝程（約5%側移角）。	This study employed a cyclic loading experiment as the primary test for Columns P3 and P4, and the loading protocol was conducted at drift ratios of 0.25%, 0.375%, 0.5%, 0.75%, 1.0%, 1.5%, 2.0%, and 3.0%. Two cycles were performed at each drift angle. Considering the limitations to the stroke of the actuator, cyclic loading was pulled to 3% drift before it was further pushed to a drift of 5%. Prior to the single-cycle pushover test, a pseudo-dynamic test was conducted on Column P2. An artifi cial time-history compatible with the design response spectrum according to the seismic design specifi cation for highway bridges (MOTC, 2009) was developed. Because the Niu-Dou Bridge was situated in Yilan County, the data pertaining to the earthquake event on March 31, 2002 (Richter scale of 6.8) in the Niu-Dou region of Sansing Township were used in this study. The design parameters were Ss D = 0.8 and S1 D = 0.45. The ground motion record was selected from station ILA025. In the experiment, the original time history for east-west (PGA = 90.74 Gal) and southnorth (PGA = 118.62 Gal) directions was assembled into a new ground acceleration. Subsequently, an artifi cial time history compatible with the design response spectrum was created. Considering the total duration of the original record was relatively long, and the time limitation of the on-site operation and system stability, only the main 40 s vibration record was adopted as the input ground acceleration for the experiment.