共查询到20条相似文献，搜索用时 46 毫秒
1.
采用钢纤维混凝土(SFRC30)配合比设计对双牌水库溢流面工程进行改造.在试验分析钢纤维品种、掺量对钢纤维混凝土力学性能及工作性能影响的基础上,选择SFRC30混凝土所用钢纤维的品种和合理掺量.并对SFRC30的力学性能、干缩性能、抗冲磨性能等进行试验,结果表明:SFRC30的性能较基准混凝土有较明显的提高. 相似文献
2.
SINGH Bhupinder SINGH S.P KAUSHIK S.K. 《浙江大学学报(A卷英文版)》2007,8(2):257-263
INTRODUCTION Finite Element (FE) procedures are at present widely used in engineering modelling and analysis and employed extensively in the analysis of solids and structures and heat transfer and fluids (Bathe, 1996). The essence of FE solution of an engineering problem is that a set of governing algebraic equations is es-tablished which are then solved with the help of a digital computer. The first practical FE procedures were employed in linear analysis of solids and struc-tures (B… 相似文献
3.
INTRODUCTION A number of experimental fatigue studies were conducted on plain concrete as well as on steel fibre reinforced concrete (SFRC) beams of different sizes under different loading conditions. Murdock and Kesler (1958) investigated the effect of stress ratio on the fatigue strength of plain concrete. Batson et al.(1972) reported fatigue strength of 74% and 83% of the first crack static flexural strength at 2 million cycles of complete reversed and not-reversed loads respectively… 相似文献
4.
This paper establishes a 3D numerical model for 15# hydropower house of the Three Gorges Project (TGP) and performs a nonlinear static and dynamic damage analysis. In this numerical model, a coupling model of finite and infinite elements for simulating infinite foundation of hydropower station is adopted. A plastic-damage model based on continuum damage mechanics, which includes the softening and damage behavior under tension is considered for the concrete material. The dynamic equilibrium equations of motion are solved by using the HilberHughes-Taylor (HHT) time integration method. Firstly, the static damage response analysis of the hydropower station is conducted due to high tensile stress resulting from large water head and diameter of an inlet pipe. Then, on the basis of static simulation, the dynamic damage analysis of hydropower house subjected to earthquake motion is simulated. Numerical results show that under large water head and diameter of an inlet pipe of the project, the damages are mainly located near the top of the spiral case from the inlet section to the 0° section; under combined loadings of static loads and earthquake, the damages of the concrete surrounding the spiral case increase insignificantly; however, some damages occur on the side walls of the main powerhouse. 相似文献
5.
In Order to reduce economic and life losses due to terrorism or accidental explosion threats,reinforced concrete(RC)slabs of buildings need to be designed or retrofitted to resist blast loading.In this paper the dynamic behavior Of RC slabs under blast loading and its influencing factors are studied.The numerical model of an RC slab subjected to blast loading is established using the explicit dynamic analysis software.Both the strain rate effect and the damage accumulation are taken into account in the material model.The dynamic responses of the RC slab subiected to blast loading are analyzed,and the influence of concrete strength,thickness and reinforcement ratio on the behavior of the RC slab under blast loading iS numerically investigated.Based on the numerical results.some principles for blast-resistant design and retrofitting are proposed to improve the behavior of the RC slab subjected to blast loading. 相似文献
6.
In this study, an artificial neural network （ANN） model for studying the strength properties of steel fiber reinforced concrete （SFRC） containing fly ash was devised. The mixtures were prepared with 0 wt%, 15 wt%, and 30 wt% of fly ash, at 0 vol.%, 0.5 vol.%, 1.0 vol.% and 1.5 vol.% of fiber, respectively. After being cured under the standard conditions for 7, 28, 90 and 365 d, the specimens of each mixture were tested to determine the corresponding compressive and flexural strengths. The pa- rameters such as the amounts of cement, fly ash replacement, sand, gravel, steel fiber, and the age of samples were selected as input variables, while the compressive and flexural strengths of the concrete were chosen as the output variables. The back propagation learning algorithm with three different variants, namely the Levenberg-Marquardt （LM）, scaled conjugate gradient （SCG） and Fletcher-Powell conjugate gradient （CGF） algorithms were used in the network so that the best approach can be found. The results obtained from the model and the experiments were compared, and it was found that the suitable algorithm is the LM algorithm. Furthermore, the analysis of variance （ANOVA） method was used to determine how importantly the experimental parameters affect the strength of these mixtures. 相似文献
7.
将Debye-Hckel理论和Onsager电导理论用于研究混凝土孔溶液中离子的扩散规律.首先,建立了饱和混凝土中离子扩散系数的计算模型,该模型考虑了离子的种类、孔溶液中离子的浓度、环境温度等因素对离子扩散系数的影响.其次,以孔溶液中氯化钠的浓度变化为例分析了离子氛半径、松弛效应、电泳效应等对孔溶液中氯离子扩散系数的影响规律,发现氯离子的扩散系数随氯化钠溶液浓度的增加而减小,离子氛半径和电泳效应是影响氯离子扩散性能的重要参数.最后,通过RCM法测定了不同水灰比混凝土的氯离子扩散系数,并将模型的计算结果与实测结果进行了对比,以验证模型的合理性,结果表明所建立的模型与实测结果较为符合. 相似文献
8.
Fibre-reinforced polymer （FRP） composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete （RC） columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short columns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design. 相似文献
9.
钢筋砼L-形截面双向拉弯构件正截面承载力的研究 总被引：1，自引：0，他引：1
对钢筋砼 L-形截面双向拉弯构件的正截面承载力进行了研究 ,还对三根钢筋砼 L-形截面双向拉弯构件进行了试验研究 .编制了计算机程序 ,可用于各种类型截面的计算 ;并用此程序对 L-形截面在双向拉弯作用下的 N- M相关曲线、等轴力下的 Mx- My相关曲线进行了计算分析 ,理论计算结果与试验结果吻合较好 相似文献
10.
We proposed a bilinearity constitutive curve model of fiber reinforced polymer （FRP） confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength, ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status, and the increase of the confinement ratio has a limited capacity to increase the compressive strength, The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is, the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles, a peak/inflection point stress and strain model, and a compressive strength and ultimate strain model. 相似文献
11.
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. 相似文献
12.
采用ABAQUS有限元软件对各种强度等级下各龄期钢筋混凝土梁的受扭性能进行分析。各龄期混凝土的本构关系采用塑性损伤模型,受拉指标采用断裂能。有限元分析结果表明:各龄期混凝土的抗扭承载力随龄期的增长而增长,开裂前早龄期混凝土梁的抗扭承载力主要由混凝土承担,钢筋的贡献很小;前3d是混凝土扭矩增长最快的主要时间段,开裂扭矩和极限扭矩达到28 d的60%左右。最后,根据有限元参数分析结果,在现行规范的基础上提出了早龄期混凝土梁开裂扭矩和极限扭矩的修正公式。 相似文献
13.
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. 相似文献
14.
INTRODUCTION Creep is an internal characteristic of concrete under long-term load. A long time has elapsed since the first discovery of concrete creep in 1907 by Hatt. Many researches have been devoted to this complex problem ever since. However, despite major suc-cesses, the creep phenomenon is still far from being fully understood, even though the phenomenon has occupied some of the best minds in the field, such as Glanville, Dischinger, Troxell, Pickett, Neville, etc. Creep phenome… 相似文献
15.
通过不同纤维掺量、不同养护龄期下钢纤维混凝土的力学性能试验,研究钢纤维掺量对混凝土抗压强度和抗折强度的影响。结果表明,钢纤维对混凝土抗压强度和抗折强度均有明显增强作用,掺量为1．6％时强度最大。 相似文献
16.
The marine structures such as harbour,pier and inshore concrete terrace are exposed in adverse circumstances in a long period of time . Owing to the attack of external corrosive medium, their safety, durability and reliability decline. Especially the reinforced concrete(RC) structures in the wave splash area are more likely to be subjected to destruction and the loss is vast. Now the safety ,durability and reliability of structure have become increasingly an important subject to be studied. By way of the soaking and drying cycle test on the different mix proportions oblique section of 10 pieces of RC beams suffered artificial sea water(ASW) corrosion under 0,35,70,105,140 times of dry-wet cycles, the compared results of exerting pressure test of these beams under simply supporting were investigated. The law about the changes of the mechanical performance for RC beams with different mix proportions under different time periods for suffering corrosion of dry-wet cycles is as follows: the resistivity to ASW corrosion of the concrete specimens with various water cement ratio(various initial strength) is different ; the characters of oblique section failure for RC beams attacked by sea water are about the same as those for ordinary RC beam; along with the extension of the time for sea water attack, the bearing capacity for oblique section of RC beams varies wave upon wave. The specimens attacked by sea water for about 35 times of corrosion cycle achieve minimum bearing capacity. 相似文献
17.
CHEN Kuen-suan SUNG Wen-pei SHIH Ming-hsiang 《浙江大学学报(A卷英文版)》2005,6(8):836-843
INTRODUCTION In recent years, devastating disasters in whichreinforced concrete structures collapsed have causedmajor loss of life and property damage around thworld. Investigation of these incidents showed thathe collapses were mainly due to the poor concretquality (NCREE, 1999; SECL, 1999; Watabe, 1995)Therefore, high quality assurance in reinforced concrete (RC) structure design and manufacturing is onof the most important safety factors. To promote threliability of structure, co… 相似文献
18.
INTRODUCTION Reinforced concrete elements with box section are commonly used in horizontal subsystems and in vertical support of bridge structures. The horizontal structural members normally have box section and top flange. The vertical supports of the bridge usually have a box section also. To simplify the deduction of such structural member under combined forces, the box sections without top flange are discussed here. Fig.1 shows the typical section types of reinforced concrete members.… 相似文献
19.
为了研究沥青混凝土的疲劳特性,提出了基于双线性内聚力模型（CZM）的数值模拟方法．建立了疲劳损伤演化模型并将其与内聚力模型耦合,以反映沥青混凝土在循环荷栽作用下的软化行为．通过编制用户材料子程序。实现了疲劳损伤模型在有限元软件ABAQUS中的应用,并对劈裂疲劳试验进行了模拟．研究结果表明：模拟得到的疲劳寿命与实验室结果基本一致;疲劳损伤随加载次数的累积是非线性的,且损伤累积阶段是疲劳破坏的主要阶段;应力比增大时,损伤稳态发展阶段的寿命明显减小．可以发现提出的疲劳损伤数值模型是一种预估沥青混凝土疲劳损伤的有效方法． 相似文献
20.
Based on a series of previous studies, an experiment on the integral seismic behavior of a 1/3 scaled model of two-bay and three-story reinforced concrete frame with split columns at lower two stories is performed under cyclic loading. The original columns at lower two stories of the model frame are short columns and they are replaced by the split columns. The hysteresis curves between the horizontal cyclic load and the lateral displacement at the top of the model frame, indicate that under the cyclic loading, the model frame undergoes the process of cracking, yielding, and maxi-mum loading before being destroyed at the ultimate load. They also indicate that the model frame has better ductility, and the ratio of the ultimate displacement to the yielding displacement, reaches 6.0. The yielding process of the model frame shows that for the frame with split columns, plastic hinges are generated at the ends of beams and then the columns begin yielding while the frame still possesses the bearing and deformation capacity. The design idea of directly changing the short col-umn to long one in the reinforced concrete frame may be realized by replacing the short column with the split one. 相似文献