钢筋混凝土梁-钢管混凝土组合柱节点抗震性能试验

介绍了3个钢筋混凝土梁-钢管混凝土组合柱节点试件在梁端竖向往复荷载作用下的试验研究,其中一个为梁弯曲破坏的"强核芯区弱梁"试件,两个为核芯区剪切破坏的"强梁弱核芯区"试件。试验结果表明,三个试件都有大的变形能力,但峰值荷载时弱核芯区试件的核芯区剪切变形占节点总变形的50%以上,而强核芯区试件的这一比例很小;弱核芯区试件核芯区的箍筋和钢管屈服,而强核芯区试件核芯区的箍筋和钢管未屈服;弱核芯区试件的耗能能力小于强核芯区试件的;对于核芯区破坏的试件,减小核芯区的箍筋间距,可以增大节点的耗能能力和减小核芯区的剪切变形。     

长期荷载及氯盐侵蚀协同作用下海砂混凝土梁耐久性试验研究

通过对氯盐侵蚀及长期弯曲荷载协同作用下海砂混凝土梁的耐久性试验研究,对海砂混凝土梁试验过程中挠度的变化、梁的荷载一挠度曲线、延性和裂缝进行了研究,结果表明：与普通混凝土梁相比,氯盐侵蚀及弯曲荷载协同作用下海砂混凝土梁具有较高的刚度;使用荷载作用下海砂混凝土梁的挠度和裂缝宽度均满足正常使用极限状态的要求,海砂混凝土梁在破坏时表现出较好的延性。     

GFRP夹芯板力学性能的试验和定量评估

对广泛应用在海洋建筑中的夹芯结构的力学性能进行了分析,夹芯结构由玻璃纤维表皮包裹PVC泡沫材料或聚酯核所构成。系统的试验研究和定量评估显示,夹芯结构强度的理论预测和实际破坏机理能被有效位误差所影响,特别是存在剪力荷载的情况下。此外,由于抗剪刚度低及弹性恒定与外壳和核心材料失谐,破坏模式和强度受垂直于夹芯板中部的最终应力的影响。尤其是带有PVC泡沫核的夹芯结构,应力的交互作用导致了外壳与核心的分离破坏,而带有聚酯核的结构致使核剪力粘结破坏。借助精确的非线性模拟,对目前复杂荷载下用于设计阶段的精确的破坏标准也进行了拓展。     

夹层玻璃梁受弯性能研究

通过对24个夹层玻璃梁试件的受弯试验和试件梁整体稳定的有限元模拟分析,研究了聚乙烯醇缩丁醛(PVB)夹层玻璃梁和离子性Sentry Glas(SGP)夹层玻璃梁在无侧向支撑条件下的弯曲性能与整体稳定性能。通过试验获取了两种夹层玻璃梁在短期荷载作用下的全过程荷载-位移关系曲线、玻璃开裂形态以及破坏模式。通过有限元法分析了两种夹层玻璃梁在考虑长期荷载作用下由于胶片抗剪承载能力衰减所引起的构件破坏模式。探讨了夹层平板玻璃梁设计时玻璃强度的合理取值以及胶片类型对玻璃梁开裂后力学性能的影响。     

夹芯托梁在砖混结构改造中的研究与应用

对几何参数和纵筋配筋率相同,连接形式不同的两种夹芯托梁在相同加载方式下的受力性能进行试验研究。研究结果表明:夹芯托梁的破坏模式、裂缝的形态及发展规律、极限荷载、荷载-挠度曲线,与同配筋率的钢筋混凝土整浇参考梁相似。在夹芯托梁中,纵筋起到了主要的受力作用,而连接筋和销键梁钢筋并未承受太大的荷载。连接筋和销键梁保证了夹芯砖墙与钢筋混凝土托梁充分咬接共同作用,使得夹芯托梁具有较好的整体性,从而夹芯托梁中的砖墙挠度与混凝土梁挠度有较好的一致性。     

钢-混凝土组合转换框架试验研究

为研究钢-混凝土组合转换梁-矩形钢管混凝土柱构成的组合转换框架的受力性能,对1榀组合转换框架缩尺模型进行了竖向荷载和低周往复水平荷载试验。分析了组合转换梁在竖向荷载作用下的刚度及裂缝开展情况以及组合转换框架在水平往复荷载作用下的破坏特点、荷载-位移滞回曲线及骨架曲线、延性、屈服机制和耗能能力等力学性能。试验研究结果表明,在竖向荷载作用下,组合转换梁刚度大,抗裂性能好,满足结构正常使用要求;在水平荷载作用下,转换框架延性好,极限层间位移角大,滞回曲线对称、饱满,耗能能力强。     

预应力混凝土梁疲劳损伤机理及其尺寸效应试验研究

为了研究预应力混凝土梁在疲劳荷载作用下的疲劳损伤机理以及各种疲劳性能的尺寸效应,对三组不同尺寸的预应力混凝土简支梁进行疲劳试验研究。通过对在疲劳荷载作用下预应力混凝土梁试验数据研究分析发现:原本按照适筋梁设计的预应力梁在受到疲劳荷载作用后出现类似于少筋梁的破坏特征,这是因为梁在循环荷载作用下,不断积累的疲劳损伤,使得梁构件发生脆性破坏。其中,脆性破坏指的是梁内钢筋发生疲劳断裂。同时,预应力梁构件由于疲劳循环荷载的作用在挠度、刚度等性能方面都存在着尺寸效应,即:预应力混凝土梁的挠度随截面尺寸的增加而减小,预应力梁刚度退化的速度随着截面尺寸的增大而减小。     

混凝土夹芯复合板抗震性能试验研究

通过9片混凝土夹芯复合板的拟静力试验，对一种混凝土夹芯复合板在低周反复荷载下的抗震性能进行了研究，研究了高宽比、竖向压应力对墙板抗震性能的影响。结果表明：通过设置适当的连接件，能够保证混凝土夹芯复合板两侧混凝土面层整体工作，该种墙板具有良好的抗震性能；混凝土夹芯复合板具有较高的抗剪承载力，在水平荷载作用下最终发生正截面受压破坏，未产生剪切破坏；由于钢筋网强度较高，试件破坏时钢筋强度未得到充分发挥；墙板内的钢筋网对墙板的抗震性能具有重要影响，钢筋网应为完整的网片，不能由两片点焊拼接而成；混凝土夹芯复合板的延性与高宽比及竖向压应力有关，高宽比及竖向压应力越大，延性越好；墙板的水平抗侧承载力由正截面弯曲受压决定，其承载力可参照钢筋混凝土剪力墙计算，但计算时考虑到钢筋强度不能充分发挥作用，应将钢筋的强度乘以0.55的利用系数。     

剪弯段开双孔钢筋混凝土梁受力性能的试验研究

基于剪弯段开双孔钢筋混凝土梁受力的特点,考虑了孔洞数量、间距和位置的因素,对剪弯段开双孔梁在集中荷载作用下的受力性能进行了试验研究。研究结果表明,与未开孔钢筋混凝土梁相比,未加固开孔梁的承载力随着孔洞数量、间距和位置的变化有不同程度的降低。当孔洞位置靠近支座时,单孔梁、孔间距小于1倍孔径的双孔梁和孔间距大于1倍孔径的双孔梁的承载力分别降低了12.7%、23.3%、16.8%,破坏时梁底部钢筋均未发生屈服,呈剪压破坏状态。当孔洞位置靠近纯弯段时,孔间距小于1倍孔径的双孔梁承载力降低了6.6%,破坏时呈弯曲破坏状态;开孔梁孔周钢筋加固后的承载力与未开孔梁相比仅下降3.1%,加固效果明显,呈弯曲破坏状态。     

二次受力条件下低强度开孔梁受力性能试验研究

由于实际工程中有许多在低强度钢筋混凝土梁上开孔的情况,本文对二次受力条件下低强度开孔梁的受力性能进行了试验研究,考虑了初始荷载及孔洞位置两个影响因素,对梁的挠度、应变及承载力进行测量分析。结果表明,初始荷载大小及孔洞位置对梁的开裂荷载没有影响;随着初始荷载的增大,梁的承载能力下降,且在剪弯段开孔比在纯弯段开孔承载力下降更明显;孔洞在梁轴纵向不同位置对梁的破坏形态有影响,孔洞在跨中时梁发生弯曲破坏,在剪弯段时可能发生剪压破坏。     

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.     

In-plane shear behaviour of fibre composite sandwich beams using asymmetrical beam shear test

The in-plane shear behaviour of a new generation composite sandwich beam made up of glass fibre skins and modified phenolic core material was investigated to determine its application as shear loading component in a structural beam. Iosipescu shear test was conducted to characterise the shear properties of the fibre composite skins and the phenolic core material. The fibre composite sandwich beams were then tested under asymmetrical beam shear to determine its behaviour under in-plane shear loading. The results show that the in-plane shear behaviour of the composite sandwich beam is similar to that of the skins. A theoretical prediction of the in-plane shear strength of the composite sandwich beam was proposed and showed a good agreement with the experimental results. Based on the results of the study, the asymmetrical shear test is recommended as a test method for determining the shear properties of sandwich structures with high strength core materials.     

GFRP面板-冷弯薄壁型钢组合梁受弯性能试验研究

土木工程领域通常采用的纤维增强复合材料夹层结构主要以模量较低的轻质材料作为芯材,使其设计承载力由截面刚度控制,而非强度控制,限制了纤维增强材料强度的充分发挥。为此,提出一种轻质、高强的玻璃纤维增强复合材料（GFRP）面板-冷弯薄壁型钢组合梁（GCS组合梁）,该组合梁由GFRP面板与夹层轻质泡沫和冷弯薄壁型钢组合而成,薄壁型钢和纤维面板之间采用剪力键（抽芯铆钉）连接。通过四点弯曲试验探讨了该组合梁的破坏模式、荷载-位移曲线和应变分布的发展规律,并与传统夹层梁进行对比,分析了有无薄壁型钢增强、薄壁型钢开口方向、界面增强方式等参数对组合梁弯曲性能影响。研究结果表明：GCS组合梁具有良好的刚度和承载能力。相对于传统复合材料夹层梁,其正常使用极限状态（挠度限值L/250）和承载力极限状态下对应荷载分别提高了306.2% 和157.5%;不锈钢抽芯铆钉能有效抑制GFRP面板与压型钢板界面剥离裂纹扩展,显著改善GCS组合梁的变形能力。研究为该组合构件的加工设计与实际工程应用提供参考。     

泡桐木芯材夹层梁抗弯性能试验研究

试验研究了复合材料泡桐木芯材夹层梁抗弯性能,考察了试验构件的破坏模式、荷载-位移曲线、抗弯承载力及受弯段的应变发展规律;开展试验构件抗弯承载力的有限元模拟,试验结果与有限元分析结果吻合较好,验证有限元模拟分析可行。基于试验及有限元分析可知:整个加载过程中复合材料泡桐木芯材夹层梁表现为线弹性受力,最后破坏发生脆性破坏;受弯承载力计算可以近似采用平截面假定。文章可供轻木芯材复合材料夹层结构的抗弯设计参考。     

Out-of-plane behaviour of partially composite or sandwich beams by exact and Finite Element Methods

The out-of-plane vibrations of composite beams with interlayer slip or three-layer sandwich beams are theoretically and numerically investigated in this paper for general boundary conditions. The governing dynamics equations are derived by applying the Hamilton's principle. A Finite Element Resolution is presented for general boundary conditions, and compared to the exact solution based on the resolution of a tenth-order differential equation. The Finite Element Method may exhibit slip locking phenomenon for very stiff connection, a phenomenon widely investigated in the past for the in-plane behaviour of partially composite beams or sandwich beams. This slip locking, analogous to the shear locking for Timoshenko beams, can be faced with some relevant interpolation shape functions of the same order for each kinematics variables, namely the deflections and the torsion angle. The numerical results are presented for layered wood beams and laminated glass beams, with particular emphasis on the rate of convergence of the natural frequencies with respect to the number of Finite Elements. It is theoretically and numerically shown that the elastic spectra of the symmetrical composite beam are composed of two independent spectrums. One spectrum is independent of the connection parameter and can be studied using the solution of the non-composite action, whereas the second spectrum can be obtained from the resolution of a third-order polynomial equation using the Cardano's method. We show the phenomenon of cut-on frequency for this out-of-plane problem, a phenomenon already noticed for the in-plane Timoshenko beam vibrations. The exact method associated to a 10 degrees-of-freedom shape function can be formally associated with the dynamics stiffness method. The numerical and the exact approaches lead to the same dimensionless spectra, up to four digits.     

铝面板PMI泡沫芯夹层材料力学性能研究

对铝面板聚甲基丙烯酰亚胺(PMI)泡沫芯夹层材料进行了弯曲、平拉、压缩、剪切、侧压等试验,得到了弯曲、平拉、压缩、剪切、侧压等性能数据,为采用铝面板PMI泡沫芯夹层材料提供了设计依据.     

采用增强槽钢连接件的双钢板-混凝土组合梁受弯性能研究

为了解决常规双钢板-混凝土组合结构整体性不足的问题,提出了一种采用增强槽钢连接件的双钢板-混凝土组合结构。为研究该组合结构受弯性能,对6根采用增强槽钢剪力连接件的双钢板-混凝土组合梁开展四点弯曲试验。研究参数为核心混凝土种类(超高性能混凝土及普通混凝土)、剪跨比、钢板厚度及连接件间距。试验结果表明：合理控制距厚比和剪跨比,试件将呈现弯曲破坏形式,并展现出良好的延性,增加钢板厚度和核心混凝土强度,截面受弯承载力得到提升。提出了该双钢板-混凝土组合梁受弯承载力理论分析模型,与试验结果比较表明,该理论分析模型能较好计算该组合梁承载力。同时,基于ABAQUS软件建立采用增强槽钢连接件双钢板-混凝土组合梁精细化有限元分析模型,与试验结果验证表明,该分析模型能精确模拟组合梁受力性能,可为该种组合结构的设计与应用提供基础。     

黏弹性核组合夹芯梁的振动和热皱折

对由聚合物面层与黏弹性核构成的夹芯梁的振动和热皱折性能进行了研究。比较了夹芯板和夹芯梁的单元。将每个组合层视为一个等价的单层,假定了稳定的温度区域。公式是一个解耦的热力学公式,首先计算了梁的区域和温度,然后用于进一步的计算。研究了纤维角度、比率以及核芯厚度对单元性能的作用。研究显示,对某些纤维角度,梁单元和板单元的预测结果有很大不同。     

A finite element model based on coupled refined high-order global-local theory for static analysis of electromechanical embedded shear-mode piezoelectric sandwich composite beams with various widths

In this study, a new theory for the accurate simulation of the shear-mode behaviour of thin or thick piezoelectric sandwich composite beams is developed. The effects of transverse normal stress and transverse flexibility of layers are considered in the development of the proposed formulation. In order to increase the computational accuracy, all kinematic and stress continuity conditions are satisfied at layer interfaces. Moreover, for the first time, both the electrically induced strain components and the transverse flexibility are taken into account in the proposed formulation. Despite the fact that the number of unknown mechanical parameters in this theory is only one degree higher than the first order shear deformation theory, the accuracy is surprisingly more pronounced for the thicker beams.     

Fatigue performance of lightweight steel-concrete-steel sandwich systems

This paper investigates the static and fatigue strength behavior of a composite sandwich system, which consists of a lightweight concrete core sandwiched in between two steel plates and interconnected by J-hook connectors. For this purpose, fibre-reinforced lightweight concrete, of density less than 1450 kg/m³, and novel J-hook connectors that are capable of resisting tension and shear have been developed. Fatigue tests were carried out to study the fatigue behaviour of sandwich beams by varying the maximum applied load and load range. It is found that maximum applied load and load range affect fatigue performance independently. The maximum applied load has a significant effect on fatigue performance when the difference between it and the load range is large. Test evidence shows that considering only the load range, without taking into account the maximum applied load, may over-predict the fatigue life of the sandwich structural system. Finally, a three-parameter fatigue design equation, taking into account both the load range and maximum applied load, is proposed based on regression analysis of test data.