基于抗力時變特性的內(nèi)河框架碼頭可靠度分析
發(fā)布時間:2018-04-01 14:02
本文選題:框架碼頭 切入點:結構全壽命 出處:《重慶交通大學》2014年碩士論文
【摘要】:碼頭結構在長期使用過程中,受自然環(huán)境、使用條件和內(nèi)部材料等因素的影響,鋼筋混凝土構件易產(chǎn)生鋼筋銹蝕、混凝土碳化以及鋼筋與混凝土間粘結力降低等現(xiàn)象,導致其抗力隨時間不斷的降低。本文應用可靠度理論,提出考慮鋼筋混凝土構件時變特性的內(nèi)河框架碼頭全壽命分析方法,并通過算例說明如何運用該方法計算隨時間變化的結構物可靠度。論文的主要工作和結論包括以下內(nèi)容: (1)基于混凝土銹脹開裂過程的隨機性,考慮內(nèi)河環(huán)境中混凝土碳化引起的鋼筋銹蝕作為混凝土結構劣化的主要環(huán)境作用因素,提出了一種預測鋼筋銹蝕程度的概率模型;谠撃P,采用蒙特卡羅法模擬碼頭橫梁性能退化過程,得到鋼筋銹蝕率在不同時段的概率分布,實現(xiàn)了混凝土構件“混凝土碳化-鋼筋銹蝕-混凝土開裂-鋼筋銹蝕加劇-構件承載能力下降”的性能劣化全過程數(shù)值模擬。模擬結果表明鋼筋銹蝕率的分布特征隨時間變化。 (2)本研究將鋼筋混凝土構件的抗力和作用荷載均視為隨機過程,將其離散為設計使用期內(nèi)不同時間段相應極值的隨機變量,同時假設以最危險構件的可靠度代表整個結構系統(tǒng)的可靠度,,采用JC法計算結構物的時變可靠指標,建立了基于抗力隨時間變化的內(nèi)河框架碼頭可靠度計算模型。 (3)以某內(nèi)河鋼筋混凝土框架碼頭為背景,基于本文的研究方法,采用MATLAB編程計算碼頭構件時變可靠指標。在此基礎上分析碼頭主要構件因鋼筋銹蝕和混凝土劣化造成的可靠指標退化過程,從結構可靠性理論方面對結構的剩余壽命進行定量的評估。結果表明鋼筋開始銹蝕時間是結構抗力退化的一個重要時間節(jié)點,在碼頭設計時推遲鋼筋開始銹蝕時間對碼頭結構的安全性和耐久性有重要的意義。
[Abstract]:During the long-term use of wharf structure, due to the influence of natural environment, usage conditions and internal materials, reinforced concrete members are prone to corrosion, carbonization of concrete and reduction of bond force between reinforcement and concrete, etc.It causes its resistance to decrease over time.Based on the reliability theory, this paper puts forward a method to analyze the whole life of the inland river frame wharf considering the time-varying characteristics of reinforced concrete members, and illustrates how to use this method to calculate the reliability of structures varying with time.The main work and conclusions of the thesis include the following:1) based on the randomness of the process of concrete corrosion cracking, a probabilistic model for predicting the degree of reinforcement corrosion is proposed, considering the corrosion of steel bar caused by concrete carbonization in the inland river environment as the main environmental factor of the deterioration of concrete structure.Based on the model, Monte Carlo method is used to simulate the degradation process of wharf beam performance, and the probability distribution of the corrosion rate of reinforcement in different periods is obtained.Numerical simulation of the whole process of performance deterioration of concrete members "concrete carbonization-reinforcement corrosion-concrete cracking-reinforcement corrosion aggravation-member bearing capacity decline" has been realized.The simulation results show that the distribution of corrosion rate of steel bars varies with time.2) in this study, the resistance and the action load of reinforced concrete members are regarded as random processes, which are discretized into random variables corresponding to extreme values in different time periods of design life.At the same time, assuming that the reliability of the most dangerous component represents the reliability of the whole structure system, the time-varying reliability index of the structure is calculated by using JC method, and the reliability calculation model of the inland river frame wharf based on the variation of resistance with time is established.Taking the reinforced concrete frame wharf of a inland river as the background and based on the research method in this paper, the time-varying reliability index of wharf members is calculated by MATLAB programming.On this basis, the process of reliability index degradation caused by the corrosion of reinforcement and deterioration of concrete is analyzed, and the residual life of the structure is quantitatively evaluated from the aspect of structural reliability theory.The results show that the corrosion time of steel bar is an important time node of structural resistance degradation. It is important for the safety and durability of wharf structure to delay the start corrosion time of steel bar in the design of wharf.
【學位授予單位】:重慶交通大學
【學位級別】:碩士
【學位授予年份】:2014
【分類號】:U656.1
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