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標題: | 車輛動態特性對於橋梁頻率攫取的影響 Effect of vehicle dynamic properties on extraction of bridge frequencies |
作者: | Wei-Fan Chen 陳韋帆 |
指導教授: | 楊永斌 |
關鍵字: | 橋梁,間接量測,量測車輛,參數分析,現地實驗, bridge,indirect approach,measuring vehicle,parameter study,field test, |
出版年 : | 2015 |
學位: | 博士 |
摘要: | 利用一移動車輛通過橋梁,以攫取橋梁頻率的量測方式,稱之為橋梁間接量測法,此法係Yang和其研究團隊於2004年所提出,只須感應器安裝在量測車上,相對而言,傳統的直接量測法則須將感測器安裝於待測橋梁上。本研究係以間接量測法中所使用的量測車的動態特性,作為研究主軸,同時亦探討地面粗糙度和橋上隨機車流,對於該法的影響。
本文首先對橋梁直接振動量測法的研究,進行一定程度的回顧,從中吸取相關技術,特別是有關訊號處理方面的,以利間接量測法之發展;其次,將對橋梁的間接量測法的發展,進行全面性的回顧。接著,將對具備自身阻尼之量測車,進行兩階段的分析,藉由量測車的動態特性的參數分析,來評估車輛阻尼和頻率對於間接量測法的影響。其次,將運用隨機子空間識別法(stochastic subspace identification, SSI),考慮其在統計學上不同訊號源的非正交性,來分離量測車所得到的訊號,推導出涵蓋車橋互制效應 (vehicle-bridge interaction)的VBI-SSI識別法,可提升橋頻之識別效能。 接下來,將針對Yang的研究團隊在量測車和現地實驗方面的研究,進行詳細的回顧,並對量測車輪胎的力學特性進行探討。吾人採用充氣式輪胎與彈性剛輪兩種型式,進行實際測試分析,並提出懸浮質量模型的修正模式,以便能更精準的模擬彈性剛輪通過粗糙路面的情況。最後,吾人將使用彈性剛輪作為量測輪胎,進行現地實驗,考慮三種不同的控制參數,即量測車質量、行進速度、以及外在隨機車流量,以驗證其在實際應用的可行性。依據本文的理論模擬和現地實驗可知:間接量測法所面臨的最大難題,為路面粗糙度之存在,路面粗糙度會激盪量測車的振動,使其在頻率域中的幅值過大而影響橋頻的識別。若要增進橋梁間接量測法的工作效益,有效地提升量測車的行進速度,則唯有提高量測車的穩定性,此點可藉車重之增加達成,同時並增加橋梁本身、而非量測車的振盪能量,此點可經由橋上車流之引進而達成。 Using the vibration data recorded by a moving vehicle during its passage over a bridge to detect the frequencies of the bridge is a technique proposed by Yang and co-workers in 2004. This technique has been referred to as the “indirect approach” for measuring the bridge frequencies, which this requires the vibration sensors to be mounted only on the test vehicle. In contrast, the conventional approach relies on vibration sensors directly mounted on the bridge for measuring the bridge respone, for which the name “direct approach” is given. The objective of this study is focused on the dynamic properties of the test vehicle for use in the indirect bridge measurement. Also investigated are the effects of pavement roughness and existing random traffic flows on the identification of bridge frequencies. First, a brief review will be given of the researches on measurement of bridge dynamic properties using the direct approach. From this review, techniques that have been used in the direct approach, especially those for signal processing, will be adopted in developing the indirect approach. Next, a comprehensive review will be given of the previous studies on the indirect approach. After this, for a test vehicle equipped with internal damping, a parametric study based on a two-stage analysis technique will be carried out to process the vehicle response collected, aimed at evaluating the effect of damping and frequencies of the test vehicle on bridge frequency identification. Furthermore, the stochastic subspace identification (SSI) algorithm is modified to include the vehicle-bridge interaction (VBI) effect, resulting in the proposed so-called VBI-SSI approach, by which the noises associated with the vehicle and roughness are filtered out and the identifiability of the bridge frequencies is enhanced. Then, a detailed review will be given of the progress by Yang’s research group in designing the test vehicle and in conducting the field test, with attention paid to the mechanics properties of the tires of the test vehicle. Two types of tires will be adopted in the field measurement, i.e., the inflatable wheel and the rigid wheel with elastic surface. Meanwhile, a modified sprung mass model is proposed for the simulation of elastic-surface rigid wheels running over rough pavements. Finally, the test cart equipped with elastic-surface wheels will be used in the field test considering various control factors to analyze its applicability. From the numerical studies and field tests, it is understood that pavement roughenss is the key factor determining the efficacy of the indirect approach for identifying the bridge frequencies. The existence of pavement roughenss may amplify the vehicle-frequency peaks in the acceleration spectrum of the vehicle response, making it difficult to identify the bridge frequency peaks. Thus, in order to enhance the workability of the indirect approach under higher moving speeds, it is necessary to increase the stability of the test vehicle, say, by adding the vehicle weight, while enlarging the vibration amplitude of the bridge (rather than the vehicle), say, by allowing lagre traffic flows to exist on the bridge at the moment when the measurement is taken. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/18035 |
全文授權: | 未授權 |
顯示於系所單位: | 土木工程學系 |
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