题目：圆形纤维增强塑料缠绕混凝土柱在持续轴向压缩下的面向设计的模型分析

目的：在实际工程服役过程中,纤维增强塑料（FRP）约束混凝土柱在遭遇极限荷载前往往已经经历了长时间的轴压荷载作用。因此,相比其短期力学性能,本文旨在研究FPR约束混凝土柱在长期荷载作用后的力学性能。创新点：1.考虑长期轴压荷载作用,提出一种轴压作用下圆形截面 FRP 约束混凝土柱的长期变形分析模型;2.提出了长期轴压作用后的FRP约束混凝土本构模型,从本构关系的角度描述两个方面的影响机理。方法：运用混凝土和FRP徐变的长期变形分析迭代计算方法（图3）。结论：1.提出的长期变形分析模型实现了对FRP约束混凝土柱任意目标时刻的应力和应变状态的高效、准确预测;2.将提出的本构模型嵌入有限元软件中,有效地实现对长期轴压作用的考虑;3.基于OpenSees有限元软件,验证了长期变形分析模型和本构模型的有效性和准确性。     

方钢管混凝土研究现状

综合国内外方钢管混凝土试验与理论研究的资料,分析了目前世界上方钢管混凝土研究的先进成果,提出了方钢管混凝土的研究方向：方钢管混凝土框架的地震模拟、框架梁柱节点域的试验研究以及复杂应力下混凝土的本构模型研究．     

钢筋混凝土扭构件计算模型探析

钢筋混凝土受扭构件计算中,薄膜元理论计算模型需要一套准确的材料本构关系方程,本文考虑了钢筋混凝土受扭构件开裂后受拉混凝土的作用,分析了其对受扭构件承载力和变形的影响.对计算模型中的受拉混凝土和钢筋的本构关系方程作了改进,并对受扭构件承载力和变形做了计算,理论结果和试验结果吻合较好.     

混凝土拱坝横缝单元和损伤本构的研究（英文）

研究目的:研究混凝土拱坝多尺度横缝单元和坝体损伤。创新要点:解决了拱坝坝段单元采用不同剖分形式(即多尺度剖分形式)时,在静动力荷载下,拱坝横缝开度和坝体损伤的计算。研究方法:首先建立大尺度交接面单元和小尺度单元坝段自由度耦合,然后建立大尺度交接面单元和大尺度单元坝段横缝单元模型,并对坝体损伤本构的计算进行研究。重要结论:通过对比计算发现,通过混凝土的损伤本构计算的应力峰值和实验结果相同,下降段的应力应变曲线基本吻合。提出的不同尺度横缝单元模型对坝体应力和横缝开度的计算误差在7%以内。     

基于ABAQUS的再生混凝土棱柱体数值模拟

通过微机控制电液伺服压力试验机对再生粗骨料取代率分别为0、30%和75%的150 mm×150 mm×300 mm再生混凝土棱柱体进行轴心抗压强度试验,测得再生混凝土弹性模量。通过ABAQUS建立与试验尺寸相同的再生混凝土棱柱体有限元模型,并设置再生混凝土材料本构关系参数。对有限元模型采用时间—位移的线性加载方法进行了单轴轴心压缩模拟,以验证ABAQUS中再生混凝土棱柱体模型的正确性。     

钢筋与混凝土粘结滑移本构关系研究现状

国内外学者一直致力于研究钢筋与混凝土的粘结滑移本构关系,试图得到比较一致的结论,但由于钢筋与混凝土间传力机理复杂、影响因素多,目前尚无可以通用的公式。文章就普通钢筋混凝土和锈蚀后的钢筋混凝土两种情况下的粘结滑移本构关系的研究现状进行了阐述。     

型钢混凝土T形柱基于ABAQUS抗扭力学性能分析

因为异形柱经常承受偏心受压加受扭的复杂受力,所以理论计算比较复杂。本研究使用有限元分析软件ABAQUS对T形截面型钢混凝土柱的抗扭性能进行了数值模拟分析,并考虑混凝土塑性发展探讨不同轴压比与钢骨率对型钢混凝土T形截面柱延性与抗扭承载力的影响。利用已有的实验数据,建立构件的受压有限元模型,通过对比荷载-位移曲线验证有限元材料本构的有效性。建立三组模型分析不同轴压比与钢骨率对构件抗扭力学性能的影响,为今后型钢混凝土异形柱的应用提供参考。     

高强混凝土墙耐火性能的有限元分析

确定了钢材和混凝土热工参数和热一力本构关系,采用ABAQUS软件建立了火灾下高强混凝土墙温度分布和受力性能分析的有限元模型,计算结果得到以往实验结果的验证.在此基础上,对高强混凝土墙高温下的应力分布、混凝土裂缝以及重要影响因素进行了分析,初步了解了火灾下高强混凝土墙的力学性能,为进一步确定科学合理的抗火设计方法创造了条件.     

八种典型岩石力学流变组合模型的教学研究

岩石流变模型的学习和研究不仅在教学研究中具有重要意义,而且在工程应用中也具有指导意义.对岩石流变模型进行分析,发现岩石流变模型本构方程和蠕变方程的推导过程以及八种典型的岩石力学模型、本构方程、蠕变曲线、松弛曲线及其特性,了解各个流变模型所适用的范围,并通过对八种岩石流变模型比较,加深对岩石流变模型的认识和了解。     

弹体低速侵彻混凝土材料的数值模拟研究：靶体损伤机理及阻力机制新见解（英文）

目的：弹体冲击作用下,混凝土靶呈现三个阶段的典型破坏模式,即正面成坑、中间掘隧道及背面震塌,但对三个阶段损伤破坏机理及混凝土靶抗侵彻阻力主要影响因素的认识一直存在很大争议。拟标定近期提出的较为完善的混凝土帽盖弹塑性损伤本构,全面探究弹体低速冲击下（弹体速度低于500 m/s）混凝土拉伸、剪切及体积压缩行为对混凝土靶抗侵彻阻力及损伤破坏的影响机制。创新点：1.全面分析混凝土拉伸、剪切及体积压缩行为对混凝土靶抗侵彻阻力及损伤破坏的影响机制;2.成功预测弹体在混凝土靶掘隧道高压力阶段孔隙坍缩引起的损伤行为。方法：1.改进混凝土帽盖弹塑性本构,引入单元删除准则（公式(19)）,标定模型参数（图2）;2.与公开弹道试验定性定量结果对比,验证材料本构、数值模型和参数的合理性（图6～8）;3.数值模拟究混凝土拉伸、剪切及体积压缩行为对混凝土靶体抗侵彻能力及损伤破坏模式的影响,并与公开文献中主要发现进行讨论。结论：1.混凝土正面成坑及背面震塌的形成主要由其拉伸力学行为决定,而中间高压力掘隧道过程则由混凝土剪切及体积压缩行为决定。2.单轴压缩强度不是混凝土靶抗侵彻阻力主要影响因素,其高压力下的剪切及体积...     

Coupled elasto-plasticity damage constitutive models for concrete

The paper is to design and construct a coupled elasto-plasticity damage constitutive model for concrete. Based on the energy dissipation principle, the Hsieh-Ting-Chen four-parameter yield function is used. The model can reflect different strength characteristics of concrete in tension and compression, and reduce the limitation and lacuna of the traditional damage constitutive models for concrete. Furthermore, numerical test for concrete stress-strain relation under uniaxial tension and compression is given. Moreover, the damage process of concrete gravity dam is calculated and analyzed in seismic load. Compared with other damage constitutive models, the proposed model contains only one unknown parameter and the other parameters can be found in the Hsieh-Ting-Chen four-parameter yield function. The same damage evolution law, which is used for tension and compression, is good for determining stress-strain constitutive and damage characteristics in complex stress state. This coupled damage constitutive models can be applied in analyzing damage of concrete gravity dam and arch dam.     

A study on the contraction joint element and damage constitutive model for concrete arch dams简

A new contraction joint element model for the interface in different meshes between the arch dam sections is con- structed. The study on the elastic-plastic damage constitutive model for concrete, which is applied to multi-axial stresses, is also taken. The models of the dam-foundation-reservoir system for Xingbiling and Jinping concrete arch dams, China are calculated using the proposed contraction joint elements and the elastic-plastic damage constitutive model to verify the proposed models. Results showed that the proposed contraction joint element model has a high precision in simulating the behavior of contraction joints and the elastic-plastic damage constitutive model has a high precision in simulating the behavior of the damage to the concrete.     

A modified constitutive model for FRP confined concrete in circular sections and its implementation with OpenSees programming

OpenSees is a well-recognized open source platform with high compatibility, and it has a well-developed fiber ele- ment method to cope with nonlinear structural analysis. Fiber reinforced polymer （FRP） confined concrete can effectively improve the seismic performance of concrete structures. However, sophisticated constitutive models for FRP confined concrete are not available in the current version of OpenSees. In this paper, after reviewing several typical FRP confined concrete constitutive models, a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lain and Teng （2003）＇s model with four main modifications including the determination of FRP rupture strain, ultimate condition, envelope shape, and hysteretic rules. To embed the proposed constitutive model into OpenSees is a practical solution for engineering simulation. Hence, the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow chart. Finally, with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases, FRP confinement types and geometric properties, the utility and accuracy of the proposed model compared with Lam and Teng （2003）＇s model and new material secondary development in OpenSees were well validated.     

Effects of Temperature and Strain Rate on Dynamic Properties of Concrete

To study the dynamic properties of the concrete subjected to impulsive loading,stress-time curves of concrete in different velocities were measured using split Hopkinson pressure bar (SHPB).Effects of temperature and strain rate on the dynamic yield strength and constitutive relation of the concrete were analyzed.The dynamic mechanical properties of the reinforced concrete are subjected to high strain rates when it is at a relatively low temperature.But with temperature increasing,the temperature softening effect makes the strength of the concrete weaken and the impact toughness of the concrete is saliently relative to strain rate effect.So,strain rate effect,strain hardening and temperature softening work together on the dynamic mechanical capability of concrete and the relation between them is relatively corn plex.     

Effects of Temperature and Strain Rate on Dynamic Properties of Concrete

To study the dynamic properties of the concrete subjected to impulsive loading, stress-time curves of concrete in different velocities were measured using split Hopkinson pressure bar (SHPB).Effects of temperature and strain rate on the dynamic yield strength and constitutive relation of the con-crete were analyzed. The dynamic mechanical properties of the reinforced concrete are subjected to high strain rates when it is at a relatively low temperature. But with temperature increasing, the temperature softening effect makes the strength of the concrete weaken and the impact toughness of the concrete is saliently relative to strain rate effect. So, strain rate effect, strain hardening and temperature softening work together on the dynamic mechanical capability of concrete and the relation between them is relatively complex.     

Natural Frequency of Full-Prestressed Concrete Beam

Dynamic tests of three bonded and two unbonded full-prestressed concrete beams were carried out.The purpose was to seek the relation between prestressing force and natural frequency.Test results indicate that the frequency of prestressed concrete(PSC)beam increases with the increase in prestressing force approximately.The results are different from the dynamic characteristics of isotropic material beam subjected to compressive axial force which were put forward by Clough et al.The reason is that the beams were considered as isotropic,homogeneous,linear elastic material in the traditional analysis method.However,more accurate results are required in the analysis of frequency of PSC beam.The constitutive mode of PSC member is analyzed based on microstructure of concrete in this paper.The orthotropic linear elastic mode is used to analyze the relation between dynamic frequency and prestressing force of concrete beam,at the same time the equivalent stiffness of prestressed tendon relating to the prestressing force is added to the bending deformation stiffness of the beam.The analytical value agrees well with the test result,indicating that the current analysis method in this paper is feasible to full-prestressed concrete beam.     

NONLINEAR ANALYSIS OF REINFORCED CONCRETE RECTANGULAR SLABS USING FINITE ELEMENT METHOD

The nonlinear analysis of reinforced concrete rectangular slabs undermonotonic transverse loads is performed by finite element method.The layered rectangu-lar element with 4 nodes and 20 degrees of freedom is developed,in whichbending-stretching coupling effect is taken into account.An orthotropic equivalentuniaxial stress-strain constitutive model of concrete is used.A program is worked out andused to calculate two reinforced concrete slabs.The results of calculation are in goodconformity with the corresponding test results.In addition,the influence of tension stif-fening effect of cracked concrete on the results of calculation is discussed.