The wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges

In this paper,wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges are investigated using the wave approach.The dynamic responses,active and reactive power flow in the finite plate are calculated by the Mindlin plate theory （MPT） and classic plate theory （CPT）.To satisfy the boundary conditions and continuous conditions at the coupled junction of the finite L-shaped plate,the near-field and far-field waves are entirely contained in the wave approach.The in-plane longitudinal and shear waves are also considered.The results indicate that the vibratory power flow based on the MPT is different from that based on the CPT not only at high frequencies but also at low and medium frequencies.The influence of the plate thickness on the vibrational power flow is investigated.From the results it is seen that the shear and rotary inertia correction of the MPT can influence the active and reactive power at the junction of the L-shaped plate not only at high frequencies but also at low and medium frequencies.Furthermore,the effects of structural damping on the active and reactive power flow at the junction are also analyzed.

Research on vibration characteristics of L-shaped plate using a mobility power flow approach

L-shaped plates have become an important focuses in structural vibration research. To determine their vibration characteristics, this paper applied a mobility power flow method. Firstly, the L-shaped plate was divided into two substructures to simplify analysis. The coupled bending moment was then deduced by applying a continuous vibration property on the common edge. Next, the response on any point of the plate and the input and transmitted power flow formulas were calculated. Numerical simulations showed the distribution of the coupled bending moment and the response of the whole structure. The validity of this method was verified by the SEA approach.

Experimental Study of Moso Bamboo to-Steel Connections with Embedded Grouting Materials

Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.

Mechanical and Acoustic Performance Test of New Designed Metal Noise Barrier Unit Plate with No Riveted Connection

The modern transportation system is increasingly developed during recent years.It is an effective solution to set the noise barriers to reduce the traffic noise pollution caused by different kinds of transportation systems.Many deficiencies on concrete noise barriers and metal noise barriers with rivet structure can be eliminated by a new kind of noise barrier with no-riveted structure.The mechanical performance examination and acoustic performance test are conducted on the new-designed noise barrier with no-riveted structure.The results indicate that the maximum stress is 1.74 MPa and the maximum deformation is 1.04 mm with load acting on the unit plate.The noise reduction coefficient of this kind of no-riveted noise barrier unit plate is 0.75 and its noise insulation is 40 dB,which were conform to or superior to the standard requirements.Therefore,this new designed noise barrier meets the field application requirements of mechanical and acoustic performance,which demonstrates the noise barriers can be widely promoted.

Mechanical Properties of Moso Bamboo Connections with External Clamp Steel Plates

The Moso bamboo,a renewable green building material used in various new green buildings,have received exten-sive attention with the promotion of the concept of green buildings.To explore the mechanical properties of Moso bamboo connections with external clamp steel plates,the 16 specimens were designed by changing the bolt diameters and the end distances of the bolt holes.Their static tension tests were conducted to investigate bearing capacities and failure modes of different connection configurations.Based on test results,three failure modes of these connections were obtained,including the shear failure of bolt shank,bearing failure of bolt hole and punch-ing shear failure of the Moso bamboo.The influence of bolt diameters and end distances of bolt holes on bearing capacities of the connections was quantitatively analyzed.Based on a simplified mechanical model,the analytical models were deduced for the bolt shear failure and the bearing failure of bolt holes.The results showed that the predictive values are in substantial agreement with the experimental results.Finally,the design and manufacturing suggestions are recommended for this Moso bamboo connections.

Effect of weld on design of steel moment-resisting connection reinforced with steel plates

The foreign experimental and FEM research of steel moment-resisting connection reinforced with steel plates are introduced. The effect of weld on the connection design is studied in two ways including weld detail and geometrical detail of steel plates contrast to the reference drawing of connection design in China. The research shows that the weld plays an important role in the design of connections. The welds connecting reinforced plates and beam/column flange and the plate geometry have direct influence on the performance of the connections reinforced with plates. The study is helpful to the application of design of steel moment-resisting connection with steel plates.

Evaluation of Stiffened End-Plate Moment Connection through Optimized Artificial Neural Network

This study involves the development of an analytical model for understanding the behavior of the extended, stiffened end-plate moment connections with eight high strength bolts. Modeling of the connection as an assemblage of finite elements (FE) used for load deformation analysis, with material, and contact nonlinearities are developed. Results from the FE mathematical model are verified with results from the ANSYS computer program as well as with the test results. Sensitivity and feasibility studies are carried out. Significant geometry and force related variables are introduced;and by varying the geometric variables of the connections within a practical range, a matrix of test cases is obtained. Maximum end-plate separation, maximum bending stresses in the end-plate, and the forces from the connection bolts for these test cases are obtained. From the FE analysis, a database is produced to collect results for the artificial neural network analysis. Finally, salient features of the optimized Artificial Neural Network (ANN) via Genetic Algorithm (GA) analysis are introduced and implemented with the aim of predicting the overall behavior of the connection.

Mechanical Behavior of Light Trusses Made of Poplar Laminated Veneer Lumber and Connected with Bolts and Tooth Plates

Poplar Laminated Veneer Lumber(Poplar LVL)is a new type of engineering materials with high strength,good reliability and small variability.Poplar LVL is manufactured from the fast-growing poplar,which is widely used in packaging,furniture and others,however,is rarely adopted in construction.In order to explore the feasibility of poplar LVL trusses in construction of roof,four 4.5-m-span Fink-and-Howe trusses were designed and assembled,which were made of poplar LVL with bolted-and tooth-plated connections.Vertical static loading on the upper chord joints of a truss was imposed by self-balancing test device.The mechanical properties of trusses were examined.The ultimate load,deformation character and failure mode of each truss were measured,observed and analyzed.Furthermore,four types of analytical models with different joint connection assumptions were used to estimate the ultimate load and deflection.The results showed that the poplar LVL trusses were basically in elastic stage before the design load was reached,showing good working performance under the action of design load.The bearing capacity of the trusses of bolted connections was greater than that of the tooth-plated connections.As for the same joint connection type,the bearing capacity of Fink trusses exceeded that of Howe trusses.The poplar LVL light trusses of both types of connections showed good structural performance,which could be reasonably used for building roof systems.

A new approach for free vibration analysis of a system of elastically interconnected similar rectangular plates

A new procedure is proposed to ease the analyses of the free vibration of an elastically connected identical plates system with respect to Kirchhoff plate theory.A structure of n parallel,elastically connected rectangular plates is of concern,whereby the motion is explained by a set of n coupled partial differential equations.The method involves a new change in variables to uncouple equations and form an equal system of n decoupled plates,while each is assumed to be elastically connected to the ground.The differential quadrature method is adopted to solve the decoupled equations.To unravel the original system,the inverse transform is applied.Decoupling the equations enables one to solve them based on the solution methods available for a single plate system.This also diminishes the computational costs of such problems.By considering different boundary conditions,a case study is run to present the method and to validate the results with its counterparts,for which excellent agreement is observed.Assessing the influence of dimensionless thickness,aspect ratio,and stiffness coefficients on the frequencies reveals the different effects of them at the low order of dimensionless natural frequencies in comparison with high orders and for different boundary conditions.

纵向钢筋C型卡槽连接单向拉伸力学性能

为提高装配式纵向钢筋连接的施工效率,提出了C型卡槽连接方式,制作9个连接件并进行单向拉伸试验,观察其破坏形态,研究试件荷载-位移曲线、应变发展过程,分析不同锚固板直径对连接件连接性能的影响;基于混凝土局部受压计算公式,推导出C型卡槽连接钢筋的承载力计算公式,并给出不同锚固板直径与带锚固板钢筋直径的适配表。结果表明:锚固板直径为43 mm和48 mm的连接件发生带锚固板钢筋拉断破坏,荷载-位移曲线与单根钢筋拉伸的荷载-位移曲线相似,均能满足JGJ 107—2016和ACI 318对接头的强度要求;锚固板直径为38 mm的连接件是依据JGJ 256—2011选取锚固板直径,试验过程中发生带锚固板钢筋拔出破坏,证明按照规程取值,锚固板直径偏小,无法满足连接要求;锚固板直径为38 mm的连接件其荷载-位移曲线呈现波浪形,承载力虽小于前两者,但仍具有较好的延性和较高的残余承载力;所有连接件的C型卡槽在整个受力过程中应变值较小,始终处于弹性阶段,C型卡槽环向应变表现为压应变,C型卡槽连接钢筋承载力的理论计算结果与试验结果相符。

蜂窝梁H型柱绕弱轴向端板连接节点抗震性能研究

目的 提出一种蜂窝梁H型柱绕弱轴向端板连接节点,探究节点抗震性能及不同因素对其影响规律,为相关设计提供借鉴。方法 理论分析蜂窝梁H型柱绕弱轴向端板连接节点传力机制,建立并验证蜂窝梁H型柱绕弱轴向端板连接节点ABAQUS模型,研究端板厚度、开孔率对节点初始转动刚度、承载能力、耗能能力、延性、刚度退化及破坏形式影响规律。结果 蜂窝梁H型柱绕弱轴向端板连接节点弯矩最终由柱腹板与正向端板抗弯、柱翼缘与侧向端板抗剪承担;剪力最终由高强摩擦型螺栓连接面间摩擦力承担;端板厚度及开孔率越大,节点耗能进入蜂窝梁耗能阶段越早,连接刚度足够时节点抗震性能主要取决于蜂窝梁。结论 提出了蜂窝梁H型柱绕弱轴向端板连接节点弯矩路径传递分配系数计算方法,建议节点端板厚度应大于1倍柱翼缘厚度,开孔率取值为60%~65%。

轻钢龙骨防火组合楼板梁板节点连接试验研究

轻钢龙骨防火组合楼板是一种新型的装配式楼板,因为自重较小,同时具有较大的承载力,板底板顶附层为防火楼板,具有较好的防火能力,该种楼板作为简支板直接放置于工字钢梁上,支座处无法传递负弯矩,因此在梁顶支座处会出现一条通缝,严重影响使用效果,同时简支板体系也不符合抗震规范的要求。本文提出一种新的支座处梁板节点连接方式,目的是通过合理连接,实现支座处能够传递负弯矩,由简支变为固结。试验采用液压千斤顶对试件施加静荷载,对11个全比例节点连接试件进行研究,考虑连接件搭接长度、连接件厚度、连接所用的自攻螺钉(螺栓)的数量,以及连接件尺寸对梁板连接节点承载力和挠度的影响,并对节点连接件与C型轻钢龙骨之间的变形协调能力做出了分析。研究表明,本文提出的以Z型钢为连接件的梁板节点连接方法安全可靠,可实现该新型楼板的双跨以及多跨连接。

功能可恢复RCS混合框架结构研究进展

钢筋混凝土柱-钢梁(RCS)混合框架结构以其结合了混凝土优异的抗压性能及钢材优异的抗弯性能而受到广泛关注,而可恢复功能结构以其震后快速恢复使用功能的能力,也成为地震工程界研究的新热点。功能可恢复RCS混合框架结构可以在弯矩较大的梁端和柱脚部位设置可更换构件,实现结构的功能可恢复能力。文中简述了近年来功能可恢复RCS混合框架结构研究进展,重点关注各类型功能可恢复钢梁、功能可恢复摇摆柱脚的构造研究,介绍了功能可恢复RCS混合框架结构性能分析研究进展。最后,对功能可恢复RCS混合框架结构仍需深入研究的问题进行了展望。

基于能力保护的新型拉压双向限位装置设计方法研究

为保护通航渡槽结构缝之间止水不被破坏,提出替代止水受力的新型拉压双向限位装置.此装置力学特征类似销轴耳板连接结构,此类结构有多重破坏模式的弱点.为克服此弱点,结合《钢结构设计标准》(GB 50017—2017)中销轴耳板连接结构设计方法,在该装置的静力设计中,基于能力保护的设计思想提出了以单一销轴弯曲破坏为该装置破坏模式的设计方法.基于实体有限元数值模拟,分析了加载过程中此装置整体与各部件的受力-变形曲线特点.结果表明:以外荷载-整体变形量曲线不出现塑性特征为依据,判定装置的静力承载力大于设计外荷载、设计方法偏于安全;通过销轴的外荷载-弯曲变形量曲线与限位装置的外荷载-整体变形量曲线显现的非线性特征相一致以及板的外荷载-整体变形量曲线在加载过程中基本保持线性状态,说明板是被保护构件、装置破坏模式为单一的销轴弯曲破坏.研究结果表明此设计方法现实可行.

两边连接木盖板屈曲约束钢板剪力墙抗侧力性能试验研究

从环保角度提出一种钢木组合形式的两边连接防屈曲钢板剪力墙。基于已有的研究成果,设计两个试件,一个是没有木盖板约束的钢板剪力墙,另一个是覆盖木板作为钢板面外屈曲约束的钢板剪力墙。对试件采用位移控制加载方式进行拟静力试验,得到试件的滞回曲线。根据试验结果,分析了试件的骨架曲线、刚度退化和耗能能力。试验结果表明,木盖板抑制钢板屈曲效果较好,能够有效减小鼓曲声音;与无木盖板试件相比,有木盖板试件具有更高的承载力和更强的耗能能力。在试件破坏后,对试件进行拆卸,发现钢板腹部木盖板覆盖区域能够保持平整,拆卸后的木盖板在加载后也能保持完整。采用软件ABAQUS进行有限元分析,模拟结果和试验结果吻合,验证了模型的可行性。

叠合板式综合管廊侧墙连接节点面外抗震性能试验研究

叠合板式综合管廊属于半装配式结构,其接缝数量少,抗渗性能优越,应用前景广泛。为了研究采用灌浆套筒连接和浆锚搭接连接两种连接方式的叠合板式综合管廊侧墙在面外荷载作用下的抗震性能,该文开展了采用两类连接方式的足尺侧墙模型的面外低周反复试验,并与管廊现浇侧墙构件作对比。通过分析试件破坏模式、裂缝分布以及受力性能指标,初步揭示了不同连接方式对叠合板式侧墙面外抗震性能的影响。研究表明:叠合板式试件与现浇试件抗震性能基本一致,滞回曲线均较饱满,极限承载力与刚度退化规律基本一致,满足装配式结构等同现浇的抗震设计要求;两类叠合板式管廊侧墙试件延性系数分别为7.05和8.50,均具有良好的面外延性,满足我国抗震设计规范中变形能力要求;采用浆锚搭接连接的叠合板式试件与采用灌浆套筒连接的叠合板式试件相比,滞回曲线更加饱满,变形能力好,但峰值抗侧承载力低,相同侧向位移下损伤破坏严重;两种连接方式的均可有效传递钢筋应力直至构件破坏。

端板攻丝高强度螺栓连接受力性能试验研究

对10.9S级M16、M20高强度螺栓和Q345B端板攻丝连接与传统高强度螺栓连接受力性能进行试验对比,研究了其在单向受拉、单向受剪以及拉-剪复合受力状态下的破坏形态、受力机理和极限承载能力。试验结果表明:单向受拉时,极限承载能力和变形与传统连接方式基本一致;单向受剪时,即使是厚径比为0.8的M20螺栓,仍可实现栓杆剪断,而端板攻丝孔内牙体无明显变形破坏且攻丝连接件形式早期滑移量明显较小;拉-剪复合受力时,随着拉剪比从0.58增大到1.73,破坏形态由剪切破坏转变为受拉破坏。因此,为确保端板攻丝牙体无明显破坏,应考虑螺栓与板厚的合理设计,建议M20螺栓在单向受拉和拉-剪复合受力时厚径比不小于0.9d,3种受力状态下高强度螺栓端板攻丝连接方式的承载力与传统连接方式基本一致。试验结果分析可为工程设计提供参考依据。

内置薄钢板的纤维复合材料接头连接性能

为研究内置薄钢板的纤维复合材料接头的连接性能,对该连接接头结构展开单轴拉伸试验.采用ABAQUS重点对影响连接性能的端径比(E/D)、边径比(S_(W)/D)、列径比(S/D)和孔径厚度比(D/t)等几何连接参数进行研究.研究结果表明:内置薄钢板的纤维复合材料连接接头相较于无内置钢板的纤维复合材料连接接头,具有更大的刚度,峰值荷载和峰值位移分别提升约50%和58%,孔周应力集中现象有所降低,改善了破坏模式,表现出较好的承载能力与延性性能;几何连接参数对连接接头的承载能力和失效模式有较大的影响,为提高连接效率,建议选用参数S_(W)/D≥2、E/D≥4、4≤S/D≤5、1.6≤D/t≤2.

新型外包钢板-自攻螺钉连接胶合竹梁柱节点转动性能

针对胶合竹材不易预开槽和预开孔以及节点转动时竹材易发生横纹劈裂的问题,研究了新型外包钢板-自攻螺钉连接节点的转动性能。对T形外包钢板-自攻螺钉连接节点和双L形外包钢板-自攻螺钉连接节点共5个试件进行了单调加载试验,分析了节点的破坏模式、初始刚度、极限承载力、变形能力和延性系数。试验发现,T形外包钢板-自攻螺钉连接节点相较双L形外包钢板-自攻螺钉连接节点,各项受力性能参数均较优。布置直径小但数量多的自攻螺钉时,节点(T8×8-M)的破坏表现为钢板和自攻螺钉的受拉断裂以及与胶合竹柱连接的自攻螺钉受拉断裂,布置直径较大但数量少的自攻螺钉时,节点(T6×10-M)的破坏则表现为竹材的横纹劈裂和自攻螺钉的剪切破坏。横纹方向采用自攻螺丝加强,可改善节点的受力性能,对T形外包钢板-自攻螺钉连接节点改善更明显。现行《工程竹结构设计标准》(T/CECS 1101—2022)提供的节点设计方法偏于安全地预测胶合竹自攻螺钉连接梁柱节点的抗弯承载力。

贴敷约束阻尼层的螺栓连接板半解析动力学建模及减振分析

在太空环境中太阳翼帆板的振动难以抑制,因此太阳翼帆板的减振研究至关重要。利用双搭接螺栓连接板结构模拟太阳翼帆板的展开状态,研究了通过贴敷约束阻尼层对其进行振动抑制的方法。创建了贴敷“H型”约束阻尼层双搭接螺栓连接板结构的半解析动力学模型,包含:利用层间剪切变形原理,推导了约束阻尼层结构的应力应变关系,用复模量表征黏弹性层的阻尼特性;考虑螺栓的影响区域,提出用复面弹簧单元和修正质量模拟双搭接螺栓结合部的刚度、阻尼和质量特性;引入正交多项式作为位移容许函数,利用拉格朗日方程和Hamilton原理建立了局部贴敷“H型”约束阻尼层的螺栓连接薄板的动力学方程。进行了实例研究,通过组建的试验系统证明了所创建的复合结构半解析模型在求解固有特性及振动响应参数方面的合理性,同时试验及半解析模型计算结果均证明约束阻尼层对双搭接螺栓连接板具有减振效果。最后,基于所创建的半解析模型分析了贴敷面积及约束阻尼层厚度对双搭接螺栓连接板减振效果的影响。