本文選題：混凝土短柱 + 有限元�。� 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：混凝土具有價格低廉、來源廣泛、易于施工等優(yōu)點,是世界上運用最為廣泛的建筑材料。同時,混凝土作為一種準(zhǔn)脆性材料,其力學(xué)性能存在尺寸效應(yīng),最典型特征為抗壓強度隨尺寸的增大而降低。然而目前各國混凝土結(jié)構(gòu)設(shè)計規(guī)范均根據(jù)小尺寸試件確定混凝土強度,無法準(zhǔn)確反映大體積混凝土構(gòu)件的真實強度,進(jìn)而導(dǎo)致不同尺寸混凝土構(gòu)件可靠度不一致,為混凝土結(jié)構(gòu)設(shè)計埋下了安全隱患�，F(xiàn)階段對混凝土尺寸效應(yīng)研究多局限于試驗手段,且試件尺寸一般較小。尺寸效應(yīng)經(jīng)典理論在大尺寸范圍內(nèi)的有效性缺乏驗證。混凝土細(xì)觀數(shù)值模擬作為一種新的混凝土性能分析方法,突破了試驗條件的限制。將其運用于混凝土尺寸效應(yīng)分析將大大降低試驗量,獲取更多有效數(shù)據(jù),同時也更為方便從細(xì)觀角度分析混凝土尺寸效應(yīng)機(jī)理。本論文工作主要包含以下三方面內(nèi)容:(1)細(xì)致梳理了代表性國家和地區(qū)(包括美國、歐洲、加拿大、中國)的混凝土以及約束混凝土(FRP約束混凝土、鋼管混凝土)結(jié)構(gòu)設(shè)計規(guī)范中混凝土設(shè)計強度確定方法和思路,分析各國混凝土結(jié)構(gòu)設(shè)計規(guī)范對混凝土尺寸效應(yīng)的考慮;廣泛收集了以往文獻(xiàn)中混凝土、FRP約束混凝土和鋼管混凝土短柱軸壓承載力試驗數(shù)據(jù),將各規(guī)范確定的設(shè)計值與所收集試驗數(shù)據(jù)對比,進(jìn)一步考察混凝土尺寸效應(yīng)對現(xiàn)行各國規(guī)范設(shè)計值可靠度的影響。(2)在細(xì)觀層次上將混凝土看作是由粗骨料、水泥砂漿基體和二者之間的過渡界面層所組成的非均質(zhì)三相復(fù)合材料,編寫隨機(jī)骨料生成程序,并建立隨機(jī)骨料有限元模型;采用隨機(jī)骨料細(xì)觀有限元模型進(jìn)行混凝土的單軸壓縮破壞性試驗,分析試件破壞形態(tài)。(3)基于細(xì)觀混凝土隨機(jī)骨料模型,探究有效模擬混凝土尺寸效應(yīng)的方法,結(jié)合試驗數(shù)據(jù)驗證采用數(shù)值方法研究尺寸效應(yīng)的可行性,最后在模型有效的基礎(chǔ)上進(jìn)行參數(shù)分析;探究主動約束力對同一級配混凝土力學(xué)行為的作用,并進(jìn)一步探索其對混凝土尺寸效應(yīng)的影響,為FRP約束混凝土、鋼管混凝土的細(xì)觀數(shù)值分析奠定基礎(chǔ)。
[Abstract]:Concrete is the most widely used building material in the world because of its low price, wide source and easy construction.At the same time, as a kind of quasi-brittle material, the mechanical properties of concrete have size effect, and the most typical characteristic is that the compressive strength decreases with the increase of size.However, at present, the concrete strength is determined according to the small size concrete structure design codes, which can not accurately reflect the real strength of mass concrete members, and lead to different reliability of concrete members of different sizes.The hidden danger of safety is buried for the design of concrete structure.At present, the research on the size effect of concrete is limited to the test method, and the size of the specimen is generally small.The validity of the classical theory of size effect in large scale range is not verified.As a new method of concrete performance analysis, meso-numerical simulation of concrete breaks through the limit of test conditions.Applying it to size effect analysis of concrete will greatly reduce the test quantity and obtain more effective data. At the same time, it is more convenient to analyze the mechanism of size effect of concrete from a mesoscopic point of view.This paper mainly includes the following three aspects: 1) combing the concrete of representative countries and regions (including the United States, Europe, Canada, China) and confined concrete FRP confined concrete.In the design code of concrete filled steel tube (CFST) structure, the concrete design strength determination method and train of thought are analyzed, and the size effect of concrete is considered in the concrete structure design codes of various countries.The experimental data of axial compression capacity of FRP confined concrete and short steel tubular columns in previous literatures are collected extensively. The design values determined by each code are compared with the test data collected.Further study on the effect of concrete size effect on the reliability of design values in current national codes. (2) the concrete is regarded as coarse aggregate at the meso level.The heterogeneous three-phase composite composed of cement mortar matrix and the interfacial layer between them is composed of random aggregate generation program and the finite element model of random aggregate is established.Based on the random aggregate meso finite element model, the uniaxial compression destructive test of concrete is carried out, and the failure pattern of the specimen is analyzed. Based on the random aggregate model of meso concrete, the effective method to simulate the size effect of concrete is explored.According to the experimental data, the feasibility of using numerical method to study the size effect is verified. Finally, the parameter analysis is carried out on the basis of the effective model, and the effect of active binding force on the mechanical behavior of the same grade concrete is explored.Furthermore, the influence on the size effect of concrete is further explored, which lays a foundation for the meso-numerical analysis of concrete confined by FRP and concrete filled with steel tube.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU528

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