东南大学学报（自然科学版）
東南大學學報（自然科學版）
동남대학학보（자연과학판）
JOURNAL OF SOUTHEAST UNIVERSITY
2014年
6期
1230-1234
,共5页
混凝土%损伤跨尺度演化%微裂纹模型%多尺度建模%尺寸效应
混凝土%損傷跨呎度縯化%微裂紋模型%多呎度建模%呎吋效應
혼응토%손상과척도연화%미렬문모형%다척도건모%척촌효응
concrete%trans-scale damage evolution%micro-crack model%multi-scale modeling%size effect
基于直接从混凝土破坏机理出发建立的混凝土材料微裂纹模型，对不同尺寸的混凝土三点弯梁试样进行了多尺度建模，对损伤演化导致的试样破坏进行了数值仿真分析，探讨了混凝土尺寸效应的发生机理。研究结果表明：混凝土材料微裂纹模型能成功模拟混凝土中微裂纹分布式生长、聚合、宏观裂纹形成与扩展、试样破坏的全过程；随着混凝土梁试样尺寸的增大，试样中的微裂纹数目及其分布的随机性也随之增加；这些裂纹在微细观尺度上的无序效应在损伤跨尺度演化过程中被放大，导致混凝土试样的宏观力学行为随之变化，即强度减小，断裂能增大，宏观性能的离散度减小；损伤跨尺度的非线性串级发展是导致混凝土强度尺寸效应的根源；相较于Ba-zant尺寸效应，模拟结果更符合Carpinteri多重分形尺寸效应律。
基于直接從混凝土破壞機理齣髮建立的混凝土材料微裂紋模型，對不同呎吋的混凝土三點彎樑試樣進行瞭多呎度建模，對損傷縯化導緻的試樣破壞進行瞭數值倣真分析，探討瞭混凝土呎吋效應的髮生機理。研究結果錶明：混凝土材料微裂紋模型能成功模擬混凝土中微裂紋分佈式生長、聚閤、宏觀裂紋形成與擴展、試樣破壞的全過程；隨著混凝土樑試樣呎吋的增大，試樣中的微裂紋數目及其分佈的隨機性也隨之增加；這些裂紋在微細觀呎度上的無序效應在損傷跨呎度縯化過程中被放大，導緻混凝土試樣的宏觀力學行為隨之變化，即彊度減小，斷裂能增大，宏觀性能的離散度減小；損傷跨呎度的非線性串級髮展是導緻混凝土彊度呎吋效應的根源；相較于Ba-zant呎吋效應，模擬結果更符閤Carpinteri多重分形呎吋效應律。
기우직접종혼응토파배궤리출발건립적혼응토재료미렬문모형，대불동척촌적혼응토삼점만량시양진행료다척도건모，대손상연화도치적시양파배진행료수치방진분석，탐토료혼응토척촌효응적발생궤리。연구결과표명：혼응토재료미렬문모형능성공모의혼응토중미렬문분포식생장、취합、굉관렬문형성여확전、시양파배적전과정；수착혼응토량시양척촌적증대，시양중적미렬문수목급기분포적수궤성야수지증가；저사렬문재미세관척도상적무서효응재손상과척도연화과정중피방대，도치혼응토시양적굉관역학행위수지변화，즉강도감소，단렬능증대，굉관성능적리산도감소；손상과척도적비선성천급발전시도치혼응토강도척촌효응적근원；상교우Ba-zant척촌효응，모의결과경부합Carpinteri다중분형척촌효응률。
Based on the micro-crack model established directly from the failure mechanism of con-crete material,the concrete three-point bending beam specimens with different length scales were multi-scale modeled.The damage evolution leading to samples' failure was numerically simulated and the mechanism of the size effect of concrete was discussed.The results show that the micro-crack model can successfully simulate the whole process of rupture,including the growth and aggre-gation of distributed micro-cracks,formation and propagation of macro-crack,and broken of the sample.The number of micro-cracks as well as their distribution randomness in the sample increase with the increase of the size of the concrete beam.The disorder effect of these cracks in the micro-scale view is amplified during the cross-scale damage evolution,inducing the change of macro-me-chanical behaviors of the concrete specimen,i.e.the increase of the fracture energy and the decrease of the strength and the discreteness of macroscopic properties.The concrete size effect results from the trans-scale nonlinear damage progress.Compared with the Bazant size effect theory,the simula-tion results are more consistent with the Carpinteri's size effect theory.
