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1.
ZHOU Xiaoqing HAO Hong DEEKS Andrew 《天津大学学报(英文版)》2006,12(B09):132-137
To model the damage process of masonry walls under blast loading, a dynamic continuum damage material model is constructed for brick and mortar separately. The degradation of both the stiffness and strength are governed by a damage variable. By using the proposed material model, damage and fragmentation of a typical masonry wall under blast loading at different scaled distances is calculated. The hazard level of the masonry wall to blast loading is evaluated by analyzing the numerical results. 相似文献
2.
DEEKS Andrew 《天津大学学报(英文版)》2006,12(Z1)
To model the damage process of masonry walls under blast loading, a dynamic continuum damage material model is constructed for brick and mortar separately. The degradation of both the stiffness and strength are governed by a damage variable. By using the proposed material model, damage and fragmentation of a typical masonry wall under blast loading at different scaled distances is calculated. The hazard level of the masonry wall to blast loading is evaluated by analyzing the numerical results. 相似文献
3.
Terrorist attacks using improvised explosive devices (lED) can result in unreinforced masonry (URM) wall collapse.Protecting URM wall from lED attack is very complicated.An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy.However,mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world.In this palaer,numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads.A distinctive model,in which mortar and brick units of masonry are discritized individually,is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model.The aluminum foam is modelled by a nonlinear elastoplastic material model.The material models for masonry,aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads.Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads. 相似文献
4.
Terrorist attacks using improvised explosive devices (IED) can result in unreinforced ma-sonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the per-formance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the perform-ance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elas-toplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads. 相似文献
5.
建筑砂浆胶凝材料存在的问题及对策 总被引：1，自引：0，他引：1
目前建筑砂浆使用的胶凝材料主要是水泥和石灰,存在的主要问题是：生产水泥和石灰要消耗大量的矿物资源和能源,严重破坏环境;工程中往往用高强度等级水泥配制低强度等级砂浆,造成资源浪费;水泥石灰混合砂浆的物理力学性质及耐久性差,配制工艺复杂,不利于推广干混砂浆等．其解决对策是利用具有潜在胶凝活性的工业废渣研究开发能够替代水泥和石灰的建筑砂浆新型胶凝材料． 相似文献
6.
Rocks are heterogeneous from the point of microstructure which is of significance to their dynamic failure behavior. Both the compressive and tensile strength of rock-like materials is regarded different from the static strength. The present study adopts smoothed particle hydrodynamics (SPH) which is a virtual particle based meshfree method to investigate strain rate effect for heterogeneous brittle materials. The SPH method is capable of simulating rock fracture, free of the mesh constraint of the traditional FEM and FDM models. A pressure dependent J-H constitutive model involving heterogeneity is employed in the numerical modeling. The results show the compressive strength increases with the increase of strain rate as well as the tensile strength, which is important to the engineering design. 相似文献
7.
通过制作多组试件对污水污泥页岩实心砖的轴心抗压性能进行试验,并和烧结粘土砖相对比,得出了污水污泥页岩实心砖砌体的轴心抗压强度指标值均高于相同等级条件的粘土实心砖砌体的轴心抗压强度值,为污水污泥页岩砖的实际应用提供了依据. 相似文献
8.
本试验对页岩陶粒砼小型砌块砌体在水平荷载作用下的承载能力进行了研究,试验做了三个砂浆等级三类砌体共计18个试件。通过对页岩陶粒砼砌块砌体无砼芯柱、有素砼芯柱和有插筋砼芯柱三类砌体,在水平荷载作用下承载能力的研究,得出三种砌体承载能力间定量的关系,插筋砼芯柱砌体水平承载力平均可提高167.13％,并得出三种砌体的破坏形态分别为：沿水平灰缝形成贯通裂缝破坏,砼芯柱在水平灰缝处被剪断而破坏和砌块本身产生裂缝而破坏,旨为制定页岩陶粒砼砌块砌体设计和施工规范提供参考。 相似文献
9.
再生混凝土力学性能的研究 总被引：1，自引：0，他引：1
对再生混凝土力学性能的研究进行了综述，主要包括再生混凝土力学性能的抗压强度、弹性模量、干缩与徐变。研究表明，和普通混凝土相比，再生混凝土力学性能的抗压强度低，弹性模量小，干缩与徐变较大。最后提出了再生混凝土力学性能需要进一步研究的问题。 相似文献
10.
To study the influence of slenderness on the axial compressive performance of autoclaved fly ash solid brick masonry columns, compression experiments were conducted on 12 samples of autoclaved fly ash solid brick masonry column and 4 samples of fired clay brick masonry column. The damage patterns and compressive performance were compared and analyzed. The experimental results indicate that the compressive bearing capacity decreases as slenderness increases from 3 to 18, and the compressive bearing capacity of the autoclaved fly ash solid brick masonry columns is lower than that of the fired clay brick masonry columns. The formulae for the axial compressive bearing capacity of autoclaved fly ash solid brick masonry columns were derived based on the experiments. The nonlinear FEA program ANSYS was adopted to simulate the behaviors of masonry columns. By comparing the simulation results and experimental results, it is shown that the simulation results agree well with the experimental ones. The rationality and applicability of the simulation results were verified. 相似文献
11.
冲击载荷作用下混凝土本构模型(英文) 总被引：2，自引：0，他引：2
为了更好地设计和分析混凝土结构,对冲击荷载作用下混凝土材料的力学特性进行了研究.将混凝土材料看成实体和微裂纹组成的复合材料,其中实体由粗骨料和水泥砂浆基体组成.假设水泥砂浆基体为弹性的、均匀的和各向同性的.基于Mori-Tanaka理论和Eshelby等效夹杂理论建立了冲击荷载作用下混凝土材料的动态本构模型.同时,进行了混凝土和水泥砂浆的冲击压缩试验.实验表明:混凝土和水泥砂浆都是率相关材料.在相同的冲击速度下,混凝土比水泥砂浆具有更高的承载能力,但混凝土的最大应变低于水泥砂浆材料.不论混凝土材料还是水泥砂浆材料,随着冲击速度的提高,破坏实验后试件的尺寸都逐渐减小. 相似文献
12.
利用ABAQUS有限元软件,开展不同材料微型桩—土动力相互作用的影响研究,桩身材料分别选为C40普通混凝土、C60普通混凝土、钢管混凝土、RPC混凝土。分析结果表明,由于弹性模量发生变化,不同材料微型桩的桩身弯矩存在明显差异;桩身材料的弹性模量过大会使微型桩的变形减弱;与静力荷载作用不同的是,动力荷载作用下的微型桩在上、下土层范围分别出现了一正一负两个较明显的桩周土反力峰值点。相关研究结论对指导微型桩的设计具有参考价值。 相似文献
13.
在分析传统混凝土两相复合材料弹性模量计算模型的基础上,考虑再生骨料中老旧砂浆含量的影响,分析水泥砂浆的体积与新天然骨料体积分数、再生骨料体积分数和再生骨料替代率之间的关系,建立预测再生混凝土弹性模量的三相复合材料模型。开展了不同龄期下不同骨料替代率再生混凝土弹性模量测试的试验研究,并采用所建立的各个复合材料模型与试验结果进行对比分析,建议了最适合再生混凝土弹性模量计算的复合材料模型,给出了随龄期变化时再生混凝土弹性模量的变化规律。 相似文献
14.
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. 相似文献
15.
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. 相似文献
16.
混凝土作为一种多相复合基材料，具有较高弹性模量和抗压强度及较低的抗拉强度，在受约束作用下少许收缩就会产生裂缝，裂缝产生的材性原因较多。当裂缝产生时，为保证结构的耐久性，就需要修补，修补材料的材性和基性材料的材性需要有效协调，以免产生二次裂缝。 相似文献
17.
Ultra high toughness cementitious composite (UHTCC) usually shows strain hardening and multiple cracking under static tension loads. In practice, structures could be exposed to high strain rates during an earthquake. Whether UHTCC can maintain its unique properties and provide high structural performance under seismic loading rates largely determines whether it can successfully fulfil its intended function. To determine the rate dependence of UHTCC, uniaxial tensile tests with strain rates ranging from 4×10?6 s?1 to 1×10?1 s?1 were conducted with thin plates. The experimental results showed that UHTCC had significant strain hardening and excellent multiple cracking properties under all the rates tested. The ultimate tensile strain lay in the range of 3.7% to 4.1% and was almost immune to the change in strain rates. The rate of 1×10?3 s?1 seemed to be a threshold for dynamic increase effects of the first crack tensile strength, elastic modulus, ultimate tensile strength, and energy absorption capability. When the strain rate was higher than the threshold, the dynamic increase effects became more pronounced. The energy absorption capability was much higher than that of concrete, and the average ultimate crack widths were controlled below 0.1 mm under all rates. Several fitting formulas were obtained based on the experimental results. 相似文献
18.
陈宝璠 《三明高等专科学校学报》2013,(4):94-100
以再生骨料、天然骨料、河砂、P·O42．5R．普通硅酸盐水泥、粉煤灰、S95粒化高炉矿渣粉、自研的MPE—GAA—AA—AMPS三元共聚聚羧酸类高效减水剂为主要原料,通过再生骨料不同取代率制作了520个再生骨料混凝土试块,运用普通混凝土力学性能试验方法,对再生骨料混凝土的抗压强度、回弹值、弹性模量和单轴受压进行综合试验。结果显示：再生骨料混凝土抗压强度的发展规律与普通混凝土存在一些差异：再生骨料取代率直接影响着再生骨料混凝土各龄期的抗压强度、单轴受压应力一应变关系、弹性模量以及再生骨料混凝土修正后回弹值。通过加入自研的MPEG从-从-AMPS三元共聚聚羧酸类高效减水剂,以50％再生骨料取代率,配制设计强度为30MPa的再生骨料混凝土是最切合实际的。 相似文献
19.
用标号超过425~#的水泥配制砌筑砂浆,既不经济也不合理.加入60%以上粉煤灰作混合材配制175~#、275~#砌筑水泥,符合GB/T3183-1997的要求,具有良好的社会效益和经济效益. 相似文献
20.
提出多孔材料平面微结构拓扑优化模型,在给定材料体积含量的情况下,分别以材料的体积模量和剪切模量作为目标函数,对微结构进行拓扑优化设计。等效材料常数通过数值均匀化方法计算得到,采用移动渐近线法求解该优化问题．利用敏度过滤去除拓扑优化中存在的数值不稳定性问题。数值算例验证了拓扑优化模型和算法的有效性,并分析了材料体积含量以及有限元网格粗细对优化结果的影响。 相似文献