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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/882


    Title: 腐蝕劣化混凝土橋梁承載能力之檢測與評估;Inspection and Evaluation of the Load-Carrying Capacity of Deteriorated Concrete Bridge
    Authors: 陳明正;Ming-Cheng Chen
    Contributors: 土木工程研究所
    Keywords: 混凝土橋梁;腐蝕劣化;承載能力;裂縫深度;應力波;多重中子;corrosion;load-carrying capacity;stress wave;multi-neutron source;crack;concrete;bridge;deterioration
    Date: 2005-09-30
    Issue Date: 2009-09-18 17:14:38 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 橋梁是交通網路之關鍵,其安全及可靠性直接或間接影響社會之正常運作及經濟之發展。營運中的安全檢測是必須的,然而綜觀世界各先進國家的橋梁檢測技術之現況,對於橋梁劣化狀況的檢測與評估方法仍需不斷的改進,以期可以落實公共基本設施在其生命週期中之維護工作。 本論文將混凝土橋的劣化分為RC及PC兩類來探討。 首先本研究認為RC結構劣化之最終表徵為裂縫,因此配合鋼筋加速腐蝕實驗結果及依據暫態彈性應力波傳理論,提出混凝土表面裂縫深度檢測之新方法,用來評估RC梁內部裂縫之拓展與承載能力的關聯,進而討論安全範圍內現存的承載能力與修復、補強時機(使用壽命)。 對於PC結構,本研究則認為劣化主因大多為套管滲水引起的鋼鍵腐蝕,此種劣化在部分場合並無明顯的外部徵兆,甚至也不易以其他非破壞檢測(NDT)方法確認,因此本論文依據中子與氫原子最易產生彈性碰撞而熱化的原理,提出以多重中子源及多重偵測器的組合,並適當延長偵測時間,用來檢測預力混凝土套管內是否滲水,做為PC結構劣化潛勢的判斷依據,實驗結果及檢測案例顯示:本法可有效找出預力套管的滲水位置。 依據上述檢測方式,工程人員即可結合AASHTO(2003)之載重及抗力因子評估法(LRFR),進行混凝土結構物的現況承載力之評估。 The deterioration of bridge due to reinforcement corrosion is one of the reasons causing the reduction of the load-carrying capacity of bridges. However, factors causing the steel corrosion are quite complicated and their correlations to load-carrying capacity are ambiguous. It is obvious that detail investigations and development of evaluation technologies are essential to the maintenance work in the life-cycle of infrastructures. In this thesis, the concrete structures were classified into two groups as reinforced concrete (RC) components and pre-stressed concrete (PC) components to study the associated evaluation methods of deterioration. Crack is identified as the most representative indicator for the deterioration of RC structures. Therefore, a crack tip profile inspection method based on the stress wave propagation theory is developed to assist engineers to quantify the deterioration condition of a flexural member. This inspected crack tip profile can be normalized by the locations of neutral axis obtained by the working stress design (WSD) and ultimate strength design (USD) methods respectively to obtain a deterioration index. This index can be used to determine the value of resistance factor in the AASHTO (2003) method for condition evaluation and load and resistance factor rating (LRFR) of highway bridge. The accumulating water inside the duct and anchorage of pre-stressed tendon is concerned as the main reason causing the deterioration of PC member. Therefore, the principle of elastic collision between neutrons and hydrogen atoms in the emergence of thermalization suggests the development of an inspection method with multi-neutron sources and multiple detectors to detect the existence of exceeding water content inside a PC member. Experimental results show that the detectable cover thickness of embedded watery zone in the concrete member is increased as the increase of the number of neutron source. From experimental results, a formula is derived to serve as a reference for choosing the combination of ejection source quantity, detector quantity and exposure time. After identifying the location of highly water content, other NDT methods may be applied to identify the damage state of the PC component for further safety and performance evaluations.
    Appears in Collections:[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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