【正文】 ?x=tα2Sn1。關鍵詞：橋梁工程 質量評定 可靠性 樣本The reliability in assessment of bridge quality Abstract: With the booming development of traffic in China, a large number of bridge construction projects being started in the vast land of China. Quality control and evaluation engineers of bridge during the construction bee an issue of growing concern in the mon project quality on the estimated methods of mathematical statistics，a sample of a bridge engineering quality reliability analysis methodhas be used, this method is more suitable in evaluation of the projects’ quality, which can reduce the assessment work in the past subjective wishes, and the oute of the assessment could increase objectivity and reliability.Key words: Bridge engineering，Assessment of quality，Reliability，Samples 現(xiàn)行橋梁質量評定方法中，都是利用樣本抽樣的統(tǒng)計數(shù)量來推斷整個工程質量即母體的質量情況，這就存在一個問題，即利用樣本的統(tǒng)計質量特征來估計推斷母體的質量特征的可靠性問題。因為x服從N（u，σxn）分布，所以xuσx/n服從標準正態(tài)分布，（xuσx/n)2服從 X2（1）分布。隨即取樣得到混凝土樣本強度（MPa）為：