双轴受压注芯混凝土砌块砌体强度试验研究

通过66个双轴受压强度试验,分析混凝土注芯砌块砌体双轴受压破坏面特点,利用应力比和异化参数建立破坏曲面函数;并得到强度分别随应力比及异化参数的变化规律.研究结果表明单轴受压时砌块砌体各向异性表现最明显,由异化参数变化而引起强度降低最大达到40%;而随横向应力的出现这种强度的差异逐渐弱化;最后在等压应力状态下蜕化成各向同性材料.不同宏单元体的强度随应力比呈凸向上的抛物线型分布,都是在单轴受压时取得强度最小值;在应力比α = 0.6左右取得最大值.研究结果为理论分析及结构设计提供参考.     

砌体本构关系的研究进展

介绍国内外砌体结构本构关系的研究现状和发展趋势,归纳砌体本构关系的各种类型及影响因素．根据实验数据的回归分析,得到混凝土多孔砖砌体受压本构关系的表达式．通过对国内外学者提出的不同本构关系进行比较和分析,给出了各本构关系的实用价值及存在问题,这是砌体结构内力分析、强度计算及有限元分析时必不可少的依据．最后,提出了砌体本构关系研究中存在的一些问题以及需要进一步完善的地方．     

高温作用后混凝土本构关系试验研究

钢筋混凝土结构遭受大灾作用后，在决定修复受损结构以前，必须估计结构的残余承载能力，这需要了解高温作用后混凝土和钢筋的性能，其中高温作用后混凝土的本构关系是计算结构残余承载能力的基础．     

粉煤灰砖砌体轴压本构关系试验研究

对粉煤灰砖砌体试件进行了受压全曲线试验研究,研究了其强度、破坏形态、应力-应变曲线等特征,考虑了不同砂浆强度的影响,并与普通砖砌体试验的结果进行了对比,结果表明,粉煤灰砖砌体的轴压性能与普通砖砌体类似,采用普通试验机并辅以刚性元件,能测得受压应力-应变全曲线,基于细观损伤建立的本构关系则能较好地预测其应力响应.     

约束灌芯混凝土砌块砌体轴压性能试验研究

以配筋砌块剪力墙结构端部受压区为研究对象,通过试验方法研究配筋砌块剪力墙端部受压区采用箍筋等约束后对剪力墙抗震性能的影响.共进行了24个采用8种不同方案的约束灌芯混凝土砌块砌体轴压试验,了解了约束灌芯混凝土砌块砌体轴压的破坏形态、承载能力和变形特征.通过对试验数据的分析,较详细地研究了各种形式横向约束件对灌芯混凝土砌块砌体强度和变形的影响,由试验分析结果可知:采用合理约束形式的约束砌块砌体的受压性能得到较大程度的改善.     

型钢与混凝土粘结本构关系的试验研究

通过１７个不同类型的型钢混凝土试件的拟梁式拔试验，得出了试件的粘结锚固特征强度和特征滑移值，并通过位置函数，粘结滑移基本形式建立了粘结滑移的本构关系。     

蒸压粉煤灰砖砌体本构关系试验与模拟

为研究蒸压粉煤灰砖砌体受压本构关系,对18个蒸压粉煤灰实心砖砌体试件进行轴心受压试验,研究试件的受力状况及其应力-应变关系曲线.以试验测得曲线为基础,与数值模拟数据相结合,并与国内外已有研究成果进行综合比较分析,给出蒸压粉煤灰砖砌体的本构关系建议表达式.将所得表达式代入ANSYS有限元分析软件中模拟砌体偏心受压力学性能,并将模拟值与试验值进行比较分析,验证了所得本构关系表达式的正确性.     

陶粒混凝土砌块砌体的结构性能

本文通过陶粒混凝土空心小砌块砌体的各项静力性能试验,分析了这种轻型墙体的特性,提出了工程应用计算方法,为编制黑龙江省技术规程提供科学依据。     

再生混凝土砌块砌体力学性能试验

通过对再生混凝土砌块砌体的抗压强度和抗剪强度试验,探讨了砌体的破坏过程和破坏形态,并根据试验结果分析了再生混凝土砌块砌体强度与砌块强度和砂浆强度的关系。基于试验数据计算了再生混凝土砌块砌体的强度标准值和设计值。研究结果表明：再生混凝土砌块砌体与普通混凝土砌块砌体的力学性能基本一致,且具有较好的抗压稳定性;普通混凝土砌块砌体的抗压强度和抗剪强度计算公式适用于再生混凝土砌块砌体。     

Experimental study on the compressive strength of grouted concrete block masonry based on nondestructive detection methods

Existing nondestructive detection methods were adopted to test the compressive strength of grouted concrete block masonry,i.e.the rebound method,pulling-out method and core drilling method were employed to test the strength of block,mortar and grouted concrete,respectively.The suitability of these methods for the testing of strength of grouted concrete block masonry was discussed,and the comprehensive strength of block masonry was appraised by combining existing nondestructive or micro-destructive detection methods.The nondestructive detection test on 25 grouted concrete block masonry specimens was carried out.Experimental results show that these methods mentioned above are applicable for the strength detection of grouted concrete block masonry.Moreover,the formulas of compressive strength,detection methods and proposals are given as well.     

Experimental study on water seepage constitutive law of fracture in rock under 3D stress

The test method and test result of water seepage constitutive law of fracture in rock under 3D stress are introduced. A permeability coefficient formula including the coefficient of fracture connection, normal stiffness, 3D stress, initial width of fracture and Poisson ratio is presented based on the analysis of the test theory and its result.     

Experimental investigation on strength and deformation of plain high-strength concrete under multiaxial stress state

To investigate the strength and deformation behavior of plain high-strength concrete (HSC) under multiaxial stress states,a large static-dynamic true triaxial machine was employed,and multiaxial tests were performed on 100 mm×100 mm×100 mm cubes concrete specimens.Friction-reducing pads were three-layer plastic membranes with glycerine in-between for the compressive loading plane.The tensile loading plane of concrete samples was processed by attrition machine,and then the samples were glued up with the loading plate with structural glue.Failure modes of specimens were described.The principal static compressive strengths,strains at the peak stress and stress-strain curves were measured,and the influence of stress ratios on them was analyzed as well.Experimental results show that the ratio of the compressive strength σ3f over the uniaxial compressive strength fc depends on brittleness-stiffness of concrete besides stress state and stress ratios.The formula of Kupfer-Gerstle’s and Ottosen’s failure criterion for plain HSC under biaxial compression and multiaxial stress state is proposed respectively.     

复杂应力状态下混凝土强度理论研究

混凝土的强度理论是土木、采矿和水利等众多混凝土工程中的安全性和稳定性设计的重要基础理论。对它进行研究具有重要的意义．为此，在双τ^2屈服准则的基础上，建立了两参数双τ^2强度理论，给出了材料的极限强度比，从而说明了不同的材料对应着不同的强度理论．其次，利用两参数双τ^2强度理论分析了混凝土的脆性破坏，并同某些混凝土的实验数据进行了对比，最后，讨论了中间主应力效应，结果表明，运用两参数双τ^2强度理论分析混凝土强度的结果是令人满意的．     

A macro-meso constitutive law for concrete having imperfect interface and nonlinear matrix

The overall behavior of concrete depends on its meso structures such as aggregate shape, interface status, and mortar matrix property. The two key meso structure characters of concrete, bond status of interface and nonlinear property of matrix, are considered in focus. The variational structure principle is adopted to establish the macro-meso constitutive law of concrete. Specially, a linear reference composite material is selected to make its effective behavior approach the nonlinear overall behavior of concrete. And the overall property of linear reference composite can be estimated by classical estimation method such as self-consistent estimates method and Mori-Tanaka method. This variational structure method involves an optimum problem ultimately. Finally, the macro-meso constitutive law of concrete is established by optimizing the shear modulus of matrix of the linear reference composite. By analyzing the constitutive relation of concrete established, we find that the brittleness of concrete stems from the imperfect interface and the shear dilation property of concrete comes from the micro holes contained in concrete. Supported by the National Natural Science Foundation of China (Grant Nos. 50679022, 90510017, 50539090) and National Basic Research Program of China (Grant No. 2007CB714104)     

零屈服应力下混凝土三轴受压塑性模型

为了模拟混凝土真三轴压缩的力学性质,在分析混凝土真三轴和常规三轴压缩试验结果基础上,以经典塑性力学为理论基础,建立了混凝土的真三轴本构模型.模型考虑了混凝土初始屈服强度为0的实验特性,采用4参数的Hsieh-Ting-Chen作为破坏准则,假定材料强化和软化符合各向同性和非相关联的塑性流动法则,并将混凝土压缩实验中的扩容和塑性功相联系起来,把lode角引入塑性势函数中.模型与两种不同配比的混凝土立方体试件分别在6组不同加载路径下的试验结果进行了验证.     

用不同规范本构关系分析钢筋混凝土压弯截面

建立的钢筋混凝土任意截面梁柱单元材料与几何非线性耦合分析模型,取截面作为梁柱单元积分的高斯点．为研究不同混凝土本构关系对截面分析的影响,分别用我国混凝土结构设计规范、CEB规范以及美国学者建议的混凝土本构关系,对钢筋混凝土双向弯压截面进行分析比较．截面分析表明,3种本构关系对截面极限承载力影响较小,截面弯矩曲率关系曲线的上升段基本吻合,下降段存在差异．3种本构关系的分析结果与试验结果吻合均较好．     

自应力钢管轻骨料砼中核心混凝土的本构关系

总结现有的砼本构关系,经过试验和理论分析,修定了基于弹塑性理论的砼本构关系;确定了四参数强度准则的参数,使之适合于自应力钢管轻骨料砼的核心砼．     

混凝土在双向应力作用下新的破坏准则和弹塑性本构关系

讨论了混凝土在双向应力作用下的破坏准则和弹塑性本构关系。根据混凝土的破坏特性，提出一个包含二个物理参数的破坏准则。在此基础上，通过构造塑性位势导出了混凝土在双向应力作用下弹塑性本构关系。最后，该破坏准则和本构关系与混凝土实验进行了比较，从而证实了它们的有效性。