By comparing with stochastic structural analysis, relations between the two methods have been found . the response surface method is used to obtain the second order estimates of the calculated results bound . by means of viscoelastic stochastic finite element method, the instantaneous reliability, the first passage reliability and fuzzy reliability of srm grain are investigated 采用凸集合模型表示藥柱參數(shù)的不確定性,在粘彈性有限元攝動分析基礎(chǔ)上進(jìn)行了結(jié)構(gòu)的響應(yīng)區(qū)間計算,討論了概率方法和集合理論模型得到的響應(yīng)區(qū)間之間的關(guān)系,利用響應(yīng)曲面法進(jìn)行了區(qū)間的二次估計。
The numerical methods and the monte carlo method for thin-walled box girders are studied systematically . the one-dimensional stochastic finite element method for box-girders is proposed, and applied to the reliability analysis successfully . the main contributions of the thesis are as follows : 1 對薄壁箱梁結(jié)構(gòu)隨機分析的數(shù)值計算理論和蒙特卡羅法進(jìn)行深入研究,提出了基于一維離散有限元法的薄壁箱梁隨機分析理論,對薄壁箱梁結(jié)構(gòu)的可靠度進(jìn)行了分析和計算。
Based on the study for the methods of structural reliability analysis, including monte carlo method, response surface method and stochastic finite element method, response surface method ( rsm ) is selected . based on the random analysis of aqueduct's frequent actions and resistances, by rsm method together with the fem method and form method, the reliabilities of its primary poles can be analyzed and the reliability of the structure be reached 利用此方法,在對渡槽常遇荷載的不確定性分析和抗力不確定性分析的基礎(chǔ)上,結(jié)合結(jié)構(gòu)分析的確定性有限元法(fem)及可靠度計算的一次二階矩法(form),對桁架拱結(jié)構(gòu)主要受力狀態(tài)構(gòu)件進(jìn)行了可靠度分析,從而對結(jié)構(gòu)的可靠性進(jìn)行了評價。
The main purpose of this paper is to establish viscoelastic stochastic finite element method and non-probabilistic method for uncertain structural analysis of srm grain . several reliability models are analyzed and structural response of srm grain with random parameters under different loads is investigated 本文重點建立了固體藥柱不確定結(jié)構(gòu)分析的粘彈性隨機有限元方法和非概率方法,研究了藥柱的結(jié)構(gòu)可靠度計算問題以及不同載荷作用下具有隨機參數(shù)藥柱的結(jié)構(gòu)響應(yīng)問題。
Based on the anti-seismic standards and stability evaluation criteria of high arch dams, the current calculation methods for high arch dams are systematically summarized, which include the rigid body limit equilibrium method, method combing rigid body limit equilibrium and finite element, discontinuous deformation analysis method ( dda ), numerical manifold method, interface element method, fe-be-ibe coupled method, stochastic finite element method, artificial transmitting boundary and explicit fem, parallel computation and modeling test 摘要從高拱壩的抗震設(shè)防標(biāo)準(zhǔn)及動力穩(wěn)定安全判定準(zhǔn)則出發(fā),對現(xiàn)有的高拱壩計算方法,如剛體極限平衡方法、剛體極限平衡與有限元結(jié)合方法、非連續(xù)變形分析(dda)法、數(shù)值流形方法、界面元法、有限元邊界元無限邊界元耦合方法、隨機有限元、人工透射邊界和顯式有限元法、并行算法,以及模型試驗等進(jìn)行了歸納。
At first, the basic theory and general process of the abutment stability against sliding of the arch dam with common definite solution ( the limiting equilibrium method of the rigid body and finite element method ) are simply developed . then combined with, reliability computation, the stochastic finite element method is used to establish the relationship between the load effect ( stress or force ) and basic stochastic variable dealing with statistical features of variables . based on the stochastic finite element method, the reliability of the arch dam abutment stability against sliding is analyzed, and the corresponding reliability index is calculated 首先簡要介紹用傳統(tǒng)定值方法(剛體極限平衡法和有限單元法)分析拱壩壩肩抗滑穩(wěn)定的基本原理和一般過程,再與可靠度理論相結(jié)合,考慮變量的隨機特性,通過隨機有限元法建立荷載效應(yīng)(如應(yīng)力、內(nèi)力等)與基本隨機變量之間的關(guān)系,然后在隨機有限元的基礎(chǔ)上進(jìn)行拱壩壩肩抗滑穩(wěn)定的可靠度分析,計算相應(yīng)的可靠指標(biāo)。
At first, the basic theory and general process of the abutment stability against sliding of the arch dam with common definite solution ( the limiting equilibrium method of the rigid body and finite element method ) are simply developed . then combined with, reliability computation, the stochastic finite element method is used to establish the relationship between the load effect ( stress or force ) and basic stochastic variable dealing with statistical features of variables . based on the stochastic finite element method, the reliability of the arch dam abutment stability against sliding is analyzed, and the corresponding reliability index is calculated 首先簡要介紹用傳統(tǒng)定值方法(剛體極限平衡法和有限單元法)分析拱壩壩肩抗滑穩(wěn)定的基本原理和一般過程,再與可靠度理論相結(jié)合,考慮變量的隨機特性,通過隨機有限元法建立荷載效應(yīng)(如應(yīng)力、內(nèi)力等)與基本隨機變量之間的關(guān)系,然后在隨機有限元的基礎(chǔ)上進(jìn)行拱壩壩肩抗滑穩(wěn)定的可靠度分析,計算相應(yīng)的可靠指標(biāo)。
For spatial, ideal elasto-plastic girder-pane structure system, using the stochastic finite element method, the static response of structural system is analyzed . taking redistribution of internal forces into account, safety margin functions of failure modes are established . using the advanced branch-and-bound method, the significant failure modes are identified, and the reliability of structural system is evaluated by pnet method 對空間理想彈塑性梁板體系結(jié)構(gòu),采用隨機有限元計算結(jié)構(gòu)系統(tǒng)的響應(yīng)量;考慮內(nèi)力重新分配,建立失效模式的安全余量方程,用驗算點法計算失效模式安全余量的可靠性指標(biāo);用改進(jìn)的分枝限界法,尋找主要失效模式:然后用pnet法計算結(jié)構(gòu)系統(tǒng)的可靠性指標(biāo)(或失效概率)。
Meanwhile, the influence of the distribution types, cut-tail and correlation of the stochastic variable on the reliability is discussed finally, the application of the arch dam abutment stability against sliding analysis with the way of common definite solution and stochastic finite element method is tested by one practical example analyzed and calculated in our province 并討論了隨機變量的分布類型、截尾情況以及相關(guān)關(guān)系對可靠指標(biāo)的影響。最后對我省一實際工程進(jìn)行計算和分析,驗證傳統(tǒng)定值分析方法及隨機有限元方法在拱壩壩肩抗滑穩(wěn)定分析中的應(yīng)用。
Under the influences of random variabilities, during both construction period and operation period, the temperature field within a gravity dam body could be regarded as a random one . in this paper, stochastic finite element methods are suggested to deal with the random temperature field . by use of the suggested methods, the influences of random environmental and random hydration heat of concrete and the initial temperature of concrete as well as the thermal parameters of both concrete and rock foundation are all taken into account . according to a scheduled time table of construction, random temperature fields of a typical concrete gravity dam within both the construction period and the operation period are calculated by emulation the layer constructing of the dam . some useful conclusions are obtained from the computational results 由于施工期和運行期各種隨機因素的影響,使重力壩溫度場成為隨機.本文綜合考慮了環(huán)境溫度(包括氣溫和庫水溫度)、混凝土絕熱溫升、入倉溫度以及混凝土和基巖的熱學(xué)參數(shù)隨機性的影響,基于隨機有限元法,給出了重力壩隨機溫度場的計算方法,對一典型重力壩按給定的施工進(jìn)度模擬分層澆筑施工過程,對施工期及運行期前期的隨機溫度場進(jìn)行了計算,并得出了一些有益的結(jié)論