大麻纤维增强不饱和聚酯合成材料低速冲击响应

对大麻纤维增强不饱和聚酯合成材料进行低速冲击响应试验,研究无编织大麻纤维增强材料冲击性能的效果。对纤维体积分数为0,0．06,0．10,0．15,0．21,0．26的大麻纤维增强不饱和聚酯合成材料试件的冲击响应与包含相同纤维体积分数被E—玻璃纤维缠绕的试件进行比较,采用扫描电子显微镜（SEM）评估冲击后的损坏程度。当大麻纤维作为加固材料时,承载力和冲击能量吸收显著提高。结果表明：纤维体积分数、复合层压板的刚度、冲击荷载和总吸收能之间存在明确的相关性。当出现低峰荷载、低冲击能以及破坏时间小于大麻纤维增强不饱和聚酯合成材料时,不饱和聚酯合成材料控制试件显示脆性破坏的性能。冲击试验结果显示：纤维体积率含量为0．21的大麻增强加固试件的冲击响应,与包含相同纤维体积分数被E—玻璃纤维缠绕的不饱和聚酯合成材料试件具有可比性。     

偏心距对钢管混凝土叠合柱压弯性能的影响

通过设计制作7个钢管混凝土叠合柱试件,进行偏心受压试验,研究钢管混凝土试件从加载到破坏的全过程,考察试件破坏形态,实测各试件的极限承载力和荷载-纵向位移曲线,分析了偏心距对钢管混凝土叠合柱压弯性能的影响。试验结果表明,偏心距越大,钢管混凝土叠合柱的极限承载力越低;根据试件的破坏形态,钢管混凝土叠合柱表现为大偏心受压和小偏心受压两种不同的破坏形态。     

钢管混凝土叠合柱节点环梁试验研究

钢管混凝土叠合柱环梁节点是一种连接叠合柱和钢筋混凝土梁的新型节点。针对7个钢管混凝土叠合柱边节点环梁进行了试验研究,其中对2个试件采用单调静力加载试验,对2个变径宽比(环梁半径与环梁宽度的比值)试件和3个变配筋比(同侧环梁环筋面积与框架梁纵筋面积的比值)试件采用低周反复加载试验,研究节点的破坏模式、承载力、节点区钢筋应力分布和耗能情况。结果表明:钢管混凝土叠合柱环梁节点在概念上安全可行,合理的设计可以实现"强节点、弱构件";配筋比越大,节点越易发生框架梁破坏;在一定范围内,节点承载力随着径宽比的减小、配筋比的增大而提高;环梁锚固区附近钢筋应力较大,环梁内外纵筋应力分布不均匀,环梁内纵筋一般不屈服;节点的等效黏滞阻尼系数较大,表明节点的耗能能力较好。     

偏心距对钢管混凝土叠合柱压弯性能的影响

通过设计制作7个钢管混凝土叠合柱试件,进行偏心受压试验,研究钢管混凝土试件从加载到破坏的全过程,考察试件破坏形态,实测各试件的极限承载力和荷载-纵向位移曲线,分析了偏心距对钢管混凝土叠合柱压弯性能的影响.试验结果表明,偏心距越大,钢管混凝土叠合柱的极限承载力越低;根据试件的破坏形态,钢管混凝土叠合柱表现为大偏心受压和小...     

圆形钢管混凝土叠合构件抗冲击性能试验研究

开展了钢管混凝土叠合试件落锤冲击系列试验,研究了横向落锤冲击荷载下圆形钢管混凝土叠合试件的破 坏模态、整体变形和局部变形特点,将钢管混凝土叠合试件与钢管混凝土试件、钢筋混凝土试件在横向冲击荷载 下的破坏模态进行对比。分析了冲击力、轴力和跨中挠度时程曲线的特征,研究了冲击能量、轴力和钢管厚度等 参数对圆形钢管混凝土叠合试件在横向冲击荷载作用下力学性能的影响规律。研究结果表明,管外钢筋混凝土部 件与核心钢管混凝土部件能够协调互补、共同工作,叠合试件表现出良好的抗冲击性能。在该试验的参数范围内 ,随着冲击能量的增加,冲击力峰值、跨中挠度峰值、冲击持续时间增加;预加轴压力试件的冲击力峰值较大、 冲击力平台值较小;钢管厚度较大试件的冲击力峰值和冲击力平台值较大,跨中挠度峰值较小、冲击持续时间较 短。     

叠合整体式混凝土剪力墙轴心受压性能研究

通过对1个现浇和7个叠合整体式混凝土剪力墙足尺试件的轴心受压试验,考察了其在轴心荷载作用下的受力性能、破坏模态和承载力,分析高厚比、预制部分截面面积占全截面面积比例（预制率）和预制薄板板肋方向等因素对剪力墙试件轴心受压性能的影响。结果表明,叠合整体式混凝土剪力墙破坏模态分为叠合面开裂破坏和轴心受压破坏两种：叠合面开裂破坏前,有明显的开裂现象,破坏过程平缓,试件承载力较低;轴心受压破坏前,试件表面无明显的裂缝产生,破坏过程突然,承载力较高。墙体高厚比对试件的承载力影响不明显;预制率越高,压缩刚度越大,墙体竖向变形越小;预制薄板板肋对叠合墙受压性能影响较小。针对叠合整体式混凝土剪力墙轴心受压破坏模态,总结中、美两国规范及已有研究中的轴心受压构件承载力计算公式,给出了叠合整体式混凝土剪力墙的轴心受压承载力简化计算式,其计算值与试验值吻合较好。     

箍筋环扣连接预制混凝土叠合梁受剪性能试验研究

为了方便现场施工,提出了一种箍筋环扣连接预制混凝土新型叠合梁.设计制作了不同剪跨比的4个预制混凝土叠合梁试件(包括"凹"形和"凸"形叠合梁各2个)和2个现浇对比梁试件,进行单调集中加载试验.通过对试件的破坏形式、荷载-挠度曲线、钢筋应变等进行分析,系统地研究了箍筋制作工艺以及箍筋连接长度等因素对叠合梁受剪性能的影响.试...     

乏燃料接收与贮存设施减振材料动力性能试验研究

针对乏燃料运输容器在乏燃料接收与贮存设施(101厂房)的坠落冲击问题,选取减振性能较好的5种材料,以试件强度、试件厚度和冲量作为试验变量,通过STLH-1800仪器化落锤冲击试验机研究切割试件的动强度、破坏深度等动力性能指标。研究结果表明:在冲击荷载作用下,冲量和厚度一定,随材料静强度的增大,动强度也增大,冲击时间减少;冲量和强度一定,随试件厚度的增大,动强度减少或不变,冲击时间增长;强度一定,随着冲量增加,若试件厚度为65mm,动强度增加,冲击时间变长,若试件厚度为35mm,动强度变化无规律,冲击接触时间变长;质量与速度针对不同材料的敏感性不同。实际工程中应依据设计选择合适的材料。     

不同加载率作用下双材料巴西圆盘动态抗拉强度试验研究

水泥砂浆广泛应用于岩石工程中,如巷道锚喷支护及山体滑坡注浆加固等,由于温度变化,岩石与砂浆之间的过渡区容易形成微裂隙薄弱区,同时地下岩体结构又常常承受着动载荷的作用,如爆破、冲击及地震等,因此研究岩石与水泥砂浆界面过渡区(interface transition zone,ITZ)的强度及其破坏特征具有重要的意义。为此提出了岩石–砂浆双材料巴西圆盘构型,采用分离式霍普金森压杆系统对两种界面粗糙度(光滑和粗糙)的双材料巴西圆盘进行了冲击实验;同时,为了比较单一材料与双材料破坏性能的差异,还制备了单一花岗岩、砂岩和砂浆的巴西圆盘试样。为了克服双材料巴西圆盘的应力分布不均匀的问题,使用实验–数值法确定了其中心抗拉强度。并且,采用Python语言建立了两种试件批量嵌入cohesive单元的数值模型模拟双材料试件ITZ的失效过程。结果表明:(1)当动态加载率相同的条件下,双材料界面粗糙度对试件的应变率影响不大,但对试件抗拉强度影响较大;(2)相比于花岗岩–砂浆试件,界面粗糙度对砂岩–砂浆试件动态初始抗拉强度影响更大;(3)基于数值模型得出圆盘模型中心处存在切应力τ_(xy),但拉应力σ_x远大于切应力τ_(xy);(4)嵌入cohesive单元的数值模型破坏规律和现象与试验试件较为接近,校验了方法的有效性。     

预制墙板内现浇自密实混凝土叠合剪力墙抗震性能试验研究

通过5片预制普通混凝土(NC)墙板内现浇自密实混凝土(SCC) 叠合剪力墙试件,2片预制普通混凝土墙板内现浇普通混凝土叠合剪力墙试件的低周反复荷载试验,研究在不同墙体边缘构件约束形式、轴压比以及保温层设置与否等条件下,预制墙板内现浇SCC叠合剪力墙的抗震性能,分析现浇SCC与预制墙板叠合剪力墙受力全过程,以及承载能力、破坏形态、滞回曲线、骨架曲线、刚度退化曲线、延性性能、耗能能力等,并将现浇SCC与现浇NC两种叠合剪力墙进行对比。分析结果表明：现浇SCC与预制墙板叠合剪力墙具有较好的抗震性能;两侧预制墙板之间的桁架钢筋起着良好连接作用,使预制加现浇的叠合墙体能整体协同受力;预制墙板内现浇SCC叠合剪力墙承载力不低于预制墙板内现浇NC叠合剪力墙;两者的受力性能、破坏形态及裂缝分布基本相同,滞回曲线、耗能能力、刚度退化等指标接近;预制墙板内现浇SCC叠合剪力墙的延性好于预制墙板内现浇NC叠合剪力墙;轴压比从0.1增加到0.2,有利于改善叠合墙体承载力;与不设置边缘构件叠合剪力墙相比,边缘构件采用暗柱形式的叠合剪力墙整体工作性能增强。     

Monitoring the effects of impact damages on modal parameters in carbon fiber entangled sandwich beams

The aim is to study the impact toughness of two types of entangled sandwich materials (heavy and light) with the help of vibration testing. A simple case of symmetrical impacts is studied in this article as no literature is available regarding impact tests on entangled sandwich materials. The variation of modal parameters with two levels of damage (BVID and Damage not apparent on the surface) is studied. Vibration test results show that the light entangled specimens possessing good damping capabilities seem more sensitive to impact damage than the heavy ones. Furthermore, damping is found to be more sensitive to damage than the stiffness variations, so it is reasonable to assume that damping may be used instead of natural frequency as a damage indicator tool for structural health monitoring purposes.     

复合夹层材料在活动房中的应用探讨

阐述了复合夹层材料在当前活动房设计生产中的重要性。概括了组成复合夹层材料的面板和芯材,并对各类面板、芯材的优缺点进行了比较分析,指出泡沫塑料和轻木是形成新型复合夹层材料的重要基础。对比分析金属与非金属两种夹芯板在不同环境下的适应性,得出玻璃钢将广泛应用于活动房复合夹层板的结论。     

Steel-concrete-steel sandwich composite structures subjected to extreme loads

This paper summarizes the latest research and development work on steel-concrete-steel (SCS) sandwich composite structures for the use as Arctic offshore platform, and to resist impact and blast loads. Current development of ultra-lightweight cement composite (ULCC) and a floatable structural cement composite (FSCC) to be used as infilled materials for SCS sandwich structure are presented. This paper aims to advance the application of SCS sandwich composite with the use of steel plate and lightweight concrete materials. A series of tests on lightweight SCS sandwich panels with shear connectors has been carried out. The superior performance of SCS sandwich panel is demonstrated. The results show that SCS sandwich with novel J-hook connectors is effective in preventing plate separation from concrete core, maintaining the structural integrity.     

Impact tests on steel–concrete–steel sandwich beams with lightweight concrete core

This paper studies the impact performance of Steel–Concrete–Steel (SCS) sandwich beams consisting of a lightweight concrete core sandwiched between two face plates that are connected by J-hook connectors. Impact tests were carried out by dropping free weights on to sandwich beams to investigate their structural response against impact loads. Test results revealed that the proposed J-hook connectors provide an effective means to interlock the top and bottom steel face plates, preventing them from separation during impact. The use of fibres in concrete core and J-hook connectors for composite action enhances the overall structural integrity of the sandwich beams when compared with those without such enhancement. An elastic–plastic analysis method is developed to predict the force-indentation relationship of sandwich sections subjected to local impact. Dynamic analysis based on the local force-indentation relationship is carried out to predict the impact force and global response behavior of the sandwich beams. The predicted results are compared with those obtained from the tests to validate their accuracy so that they can be used to evaluate the performance of sandwich beams under low velocity hard impact.     

Crashworthiness investigation of kagome honeycomb sandwich cylindrical column under axial crushing loads

For the classic thin-walled energy absorber, the energy dissipation during a collision is concentrated over relatively narrow zones. This means that a great deal of materials of the columns do not participate in the plastic deformation or not enter into the large plastic deformation stage. To expand the plastic deformation zones and improve the energy absorption efficiency, a new type of kagome honeycomb sandwich bitubal circular column is presented in this paper. This innovative impact energy absorber is made of two circular aluminum tubes filled with core shaped as a large-cell kagome lattice. The interaction effect, deformation mode and energy absorption characteristics of the composite structure are investigated numerically. Observing the collapsing process, it is found that the kagome lattices buckle first, which triggers the outer and inner skin tubes to fold locally. This behavior increases the plastic deformation areas. Moreover, the presence of the outer and inner tubes strengthens the buckling capacity of kagome cell. Furthermore, the folded tube walls intrude into the gap of the honeycomb cell, which further retards the collapse of the honeycomb cell. So the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. In addition, the effects of geometrical parameters of the kagome honeycomb on the structural crashworthiness are studied. It is found that the cell wall thickness and cell distribution (cell number in the circumferential direction) have distinct effects on the specific energy absorption. Besides, we also studied the foam-filled column with the same foam density as the kagome honeycomb and compared it with the kagome sandwich structure. It is found that the kagome sandwich column has higher mean crash force and better energy absorption characteristics.     

砖-粉煤灰砌块夹心复合墙体传热系数研究

为计算砖-粉煤灰砌块夹心复合墙体传热系数,分析其热工性能,进行了普通砖墙体、普通砖-粉煤灰砌块夹心复合墙体、再生砖墙体和再生砖-粉煤灰砌块夹心复合墙体的传热系数试验.依据普通砖、再生砖及粉煤灰砌块导热的基本机理,结合现有研究成果,给出了这几种材料的导热系数与温度、湿度的关系表达式,并提出了适用于工程设计的传热系数真实值计算方法.通过分析试件传热系数的试验值、理论值及真实值,证明真实值计算方法正确合理;用再生砖替代普通砖应用于砖-粉煤灰砌块夹心复合墙体同样能达到较好保温效果,这可为再生砖的应用及砖-粉煤灰砌块夹心复合墙体建筑节能细化设计提供依据.     

燃烧条件下格构增强泡桐木夹芯板热传导模型

以单向格构增强泡桐木夹芯板为火灾试验的研究对象,建立了夹芯板的一维热传导模型,并用有限差分法计算了夹芯板的温度梯度;同时,通过夹芯板火灾试验进行了模型验证.结果表明:夹芯板在不同时间段内沿厚度方向存在明显的温度梯度;夹芯板在承受60min的火灾或者高温时,其受热面板与芯材均发生了不同程度的热分解,材料炭化并形成炭化层,阻止了热量传导;夹芯板中性轴以上部分的变化较小,性能稳定,具有一定承载能力.另外,通过分析受热过程中芯材与格构的温度变化,验证了芯材对格构性能的影响.     

Impact of varying area of polluting surface materials on perceived air quality

A laboratory study was performed to investigate the impact of the concentration of pollutants in the air on emissions from building materials. Building materials were placed in ventilated test chambers. The experimental set-up allowed the concentration of pollution in the exhaust air to be changed either by diluting exhaust air with clean air (changing the dilution factor) or by varying the area of the material inside the chamber when keeping the ventilation rate constant (changing the area factor). Four different building materials and three combinations of two or three building materials were studied in ventilated small-scale test chambers. Each individual material and three of their combinations were examined at four different dilution factors and four different area factors. An untrained panel of 23 subjects assessed the air quality from the chambers. The results show that a certain increase in dilution improves the perceived air quality more than a similar decrease in area. The reason for this may be that the emission rate of odorous pollutants increases when the concentration in the chamber decreases. The results demonstrate that, in some cases the effect of increased ventilation on the air quality may be less than expected from a simple dilution model.     

弦支钢丝网架混凝土夹芯板的基本特性分析

弦支混凝土集成屋盖结构是在张拉整体及弦支结构的基础上提出的一种新型的预应力钢-混凝土复合屋面结构,该结构具有跨度大、施工安装方便、工业化程度高等优点,但它在通过增加预制钢筋混凝土板厚度来提高结构刚度的同时,也会导致结构本身自重的增大。钢丝网架混凝土夹芯板是一种新型轻质建筑板材,该板材具有重量轻、刚度大、承载能力强等优点。在弦支混凝土板基础上提出弦支钢丝网架混凝土夹芯板的概念,通过有限元软件对其基本特性进行研究,主要包括拉索预应力设计、结构自振特性以及钢丝网架混凝土夹芯板的裂缝控制。     

超低能耗预制混凝土夹心保温墙板拉结件热工性能分析

试验研究了保温层厚度为250 mm夹心保温墙板的热工性能.结果表明:常规保温材料厚度为250 mm时,采用不锈钢桁架或夹形和限位拉结件组合等方式,夹心保温墙板的传热系数可以达到寒冷地区超低能耗外围护墙体的要求;相比FRP拉结件,金属拉结件会产生更大的热桥效应,对预制夹心保温墙板的传热系数有较大影响;随着拉结件传热通道的...