人致荷载作用下楼层网架结构舒适度研究

以钢网架和组合网架为例,基于拟夹层板法理论分析和数值模拟相结合的方法,提出了人致荷载作用下楼层网架结构的动力响应计算方法,分析了步行、跳跃荷载作用下楼层网架结构的加速度响应,得到了楼层网架结构基频在2.5~8Hz范围内时的最大加速度响应变化规律,并给出了其满足舒适度要求的频率限值。     

大跨度桥梁多目标等效静力风荷载基向量法

由于结构抖振响应计算复杂,目前主流风荷载设计规范均采用等效静力风荷载做等代替换。文中以桥梁结构为研究对象,对抖振响应的多目标等效静力风荷载计算方法进行研究。首先,采用经典的荷载-响应相关（LRC）法获得大跨度桥梁主梁各节点处的等效静力风荷载向量,并组成荷载矩阵;其次,采用本征正交分解（POD）技术获得的本征模态矩阵;然后,以主梁的抖振响应极值为等效目标,选取的前i阶本征模态作为构建等效静力风荷载的基向量,获得最小二乘意义的多目标等效静力风荷载;最后,以东海大桥为例对该方法的有效性进行验证。结果表明,由于同时包含了脉动风荷载和抖振响应的主要信息,同时是依据重要程度排序,按照文中方法获得的多目标等效静力风荷载在抖振响应计算精度和荷载分布的合理性方面均表现良好。     

基于支持度的加速度传感器布置方法

在结构物上布置加速度传感器是实时监测结构物振动信息或模态信息的重要手段,而加速度传感器布置的数量和位置是影响监测结果的重要因素。本文的方法首先计算结构有限元模型在环境激励作用下的响应信息,然后计算出待选测点的综合支持度,最后根据综合支持度的大小判定布置加速度传感器的位置。本文以网架结构为例,验证了该方法的有效性。     

风力作用下深圳市民中心屋顶网架结构的智能健康监测

本文以深圳市民中心屋顶网架结构为工程背景,详细探讨了仅需要有限数量传感器就可实现对风力作用下大跨度复杂体型屋盖网架结构整体工作状态的自动监测和未知损伤的自动诊断的智能方法。此方法的关键技术有:网架结构工作状态的智能监测技术,支承钢牛腿工作状态的智能监测技术,网架结构节点焊缝拉裂损伤的自动诊断技术,有损伤网架结构抗倒塌的实时安全评定技术。通过这些智能方法的应用,成功地实现了在最经济的条件下对整个网架结构的全面健康监测。     

用高频底座力天平研究广州西塔的风效应

广州西塔总高度432m,是目前华南地区的最高建筑,风荷载是该超高层建筑的控制荷载.采用高频底座力天平方法对该建筑的模型进行详细的风洞试验,根据试验结果计算了该结构的风振响应和基底荷载,分析了流场湍流度、现有周边主要建筑结构和待建的东塔对西塔风振响应的影响.结果表明:湍流度对静风荷载影响甚少,但动力风荷载尤其是其背景部分以及结构顶部的加速度则随湍流度的增大而增大;东塔对西塔的干扰影响体现在加速度上,它可以使西塔的结构顶部加速度增加127%.文中对结构模态阻尼比和峰值因子的取值对结构风振响应的影响也进行了讨论.     

某复杂钢结构网架设计方法研究

某复杂钢结构网架在建筑上造型独特,结构上存在许多大跨度、大悬挑部分,杆件受力情况复杂;结构受风面积大、阻尼比小,自振周期又与自然风的卓越周期非常接近,属于风敏感结构。从结构找形、数值风洞和结构整体有限元分析3个方面介绍该工程的钢结构网架设计,总结该类结构的设计要点:利用反向重力荷载找形技术保证网架杆件受力的合理;在方案阶段通过数值风洞仿真计算获得建筑物表面的风荷载数据,提高有限元计算的可信度;利用通用有限元软件ANSYS对结构进行静力分析、温度分析及动力分析。为方案评定和进一步深化设计提供参考。     

某复杂钢结构网架设计方法研究

某复杂钢结构网架在建筑上造型独特,结构上存在许多大跨度、大悬挑部分,杆件受力情况复杂;结构受风面积大、阻尼比小,自振周期又与自然风的卓越周期非常接近,属于风敏感结构.从结构找形、数值风洞和结构整体有限元分析3个方面介绍该工程的钢结构网架设计,总结该类结构的设计要点:利用反向重力荷载找形技术保证网架杆件受力的合理;在方案阶段通过数值风洞仿真计算获得建筑物表面的风荷载数据,提高有限元计算的可信度;利用通用有限元软件ANSYS对结构进行静力分析、温度分析及动力分析.为方案评定和进一步深化设计提供参考.     

大跨结构屋盖风致响应状态Newmark法

本文运用状态空间Newmark法,推导了大跨屋盖结构在时域内的随机风致响应和风振系数的计算方法。通过对一大跨平面空间网架结构的建模分析,计算得到了屋盖的随机风致动力响应时程,研究了屋盖的荷载风振系数和位移风振系数,分析比较了表面两种风振系数的分布特性和变化规律,研究结果可以作为大跨度网架屋盖风荷载设计的一种参考。     

高铁站房大跨钢楼盖行车和人群荷载激励下振动响应实测与分析

对西安高铁站候车大厅在列车进出站、人群荷载激励下的结构振动响应,采用加速度传感器和信号采集分析仪进行了现场实测。分析了各测试工况下结构振动响应情况、行人-结构耦合作用、行走频率及行走状态对结构振动的影响。结果表明:列车进、出站及乘客检票进站时,不会产生较大竖向振动。人群荷载激励工况下,结构发生共振时等效正弦波峰值加速度最大为609.99 mm/s2;共振状态下,具有明显的行人-结构同步效应,且不同行走状态的人群对同一振动的反应各不相同。结构在步行频率及其整数倍频率上的振动响应较大;功率谱分析表明,人群荷载前3阶谐波分量对楼板振动贡献最大,舒适度分析时可只考虑前3阶谐波分量。采用加速度峰值会高估结构加速度响应,建议采用ESPA规范评价结构竖向舒适度。     

基于完全气弹模型风洞试验输电塔风荷载识别

按照基本缩尺律,设计、制作了输电塔完全气弹模型,并通过大气边界层风洞试验,测试了多种风速、风向条件下输电塔的位移与加速度响应。通过加速度响应功率谱识别出结构的固有频率,并采用Hilbert-Huang变换结合随机减量法识别出包含结构阻尼和气动阻尼的结构总阻尼。利用虚拟激励法建立了由测点位移响应来识别结构顺风向、横风向风荷载的方法。由识别出的风荷载谱曲线,利用非线性最小二乘法拟合得到输电塔顺风向、横风向风荷载经验公式。研究结果表明：风洞试验设计、制作的输电塔气弹模型,测试得到的模型第1阶自振频率与有限元计算结果吻合较好;横风向荷载谱形态与顺风向的相比有较大的区别,其能量分布在一个更宽的频带上,其峰值频率是顺风向的3～4倍。     

Database-assisted design methodology to predict wind-induced structural behavior of a light-framed wood building

This study investigates the applicability of the database-assisted design (DAD) methodology to predict structural reactions in a light-framed wood structure subjected to fluctuating wind pressures. Structural influence functions were determined on a 1/3-scale light-frame wood structure, which was then subjected to a wind flow, while the surface pressures and structural reactions at roof-to-wall and wall-to-foundation connections were simultaneously recorded. There was a good agreement between the DAD-predicted structural reactions and experimentally measured reactions, confirming that the DAD method is suitable for predicting the structural reactions in light-frame wood buildings. Subsequently structural reaction time histories at several connections within the building were generated using a 1:50 scale wind tunnel model of the structure and the peak structural reactions determined using the DAD method and previously obtained influence functions. When the DAD-estimated reactions were compared with reactions predicted by the ASCE 7-05 main wind force resisting system (MWFRS) method, they showed the ASCE 7 reactions were highly non-conservative(i.e. smaller than the DAD method predictions), by as much as 39% at the gable end truss. The components and cladding method showed reasonable agreement with the DAD method for the gable end and first interior truss reactions but it too underestimated the reaction loads at the second and third interior trusses by 30% and 12% respectively.     

基于数字孪生的预应力钢结构施工安全智能化分析方法

针对预应力钢结构施工过程中力学参数时变导致结构安全性能分析精度低的问题,提出了基于数字孪生的预应力钢结构施工安全智能化分析方法,结合轮辐式索桁架的结构和施工特点,总结了施工过程中结构安全性能的特征,引入了数字孪生的建模方法,并对数字孪生的构建与应用过程进行了详细描述。在此基础上,通过融合智能算法修正得到高保真性的孪生模型,并通过在模型中设置与现实施工过程相同的工况进行实时仿真,判别施工过程结构的力学性能变化情况,实现了高精度的结构安全性能分析。最后以轮辐式索桁架为研究对象,分析其施工过程的安全状态,在数字孪生的驱动下,分析拉索松弛度对结构安全性能的影响,找到了试验模型中关键拉索构件,验证了所提方法的有效性。结果表明:该研究方法融合了施工过程的时间、空间、应用等多个维度信息,实现了对结构的实时分析与科学预判,为提高结构施工的智能化控制水平提供了可靠的借鉴。     

大跨度点支式幕墙支承结构风振性能分析

广州新白云机场航站楼主楼点支式玻璃幕墙结构,长108m、高33m,采用钢桁架与预应力索桁架交叉的混合支承体系。本文针对该幕墙支承体系的三种结构方案,应用非线性有限元软件,对其风激动力性能进行分析,给出了方案合理性的评价。主要工作有:应用子空间迭代法分别对单榀索桁架和整体结构进行自振特性分析,得到相应的频率和振型;应用非线性随机模拟风振分析方法分别对三种结构方案进行整体分析,得到结构在脉动风作用下的响应时程;对风振分析结果进行统计分析,得到可供设计参考的风振系数。计算结果表明:三种结构方案的风振动力性能差别较大;其中,方案一最差,在脉动风作用下发生了弯扭跳跃式失稳;方案三最好,表现出良好的动力稳定性和整体工作性能。     

Wind effects on a long-span beam string roof structure: Wind tunnel test, field measurement and numerical analysis

The Guangzhou International Convention & Exhibition Center (GICEC) with roof dimensions of 210 m wide and 457 m long is the largest exhibition center in Asia and the 2nd largest of this kind in the world. This paper presents results from a combined study of wind tunnel test, full-scale measurement, and numerical analysis of wind effects on the long-span beam string roof structure. In the wind tunnel test, wind-induced pressures including mean and fluctuating components were measured from the roof of a 1:300 scale GICEC model under suburban boundary layer wind flow configuration. The Proper Orthogonal Decomposition (POD) method and the quasi-steady approach as well as probability analysis were adopted to estimate the characteristics of the fluctuating wind pressures on the roof. On the other hand, full-scale measurements of wind actions and wind-induced structural responses of the roof were conducted during the passage of Typhoon Nuri. The field data such as wind speed, wind direction, and acceleration responses, etc., were continuously and simultaneously monitored from a wind and structural response monitoring system installed on the roof structure during the typhoon. Detailed analysis of the field data was performed to investigate the characteristics of the typhoon-generated wind and the wind-induced vibration of the long-span roof structure under typhoon condition. The dynamic characteristics of the roof were determined from the field measurements and comparisons with those calculated from the finite element model (FEM) of the structure were made. The damping ratios of the roof structure were estimated by means of the random decrement method and the amplitude-dependent damping characteristics were presented and discussed. Finally, the full-scale measurements were compared with the model test results to examine the accuracy of the wind tunnel test results and to identify possible modelling errors in the numerical study. The results presented in this paper are expected to be of considerable interest and of use to researchers and professionals involved in designing long-span roof structures.     

Wind suction effect on long-span stiffened steel truss bridges during erection

During the erection of long-span steel truss bridges, the bridge decks and the steel truss girders are commonly constructed simultaneously in order to shorten the construction period, leading to wind suction effect on the decks when wind strikes. This effect may have a remarkable influence on the wind-resistant behavior of stiffened steel truss bridges which hold long-span cantilevers during erection, as wind suction can act together with the gravity load to increase the structural response. However, neither current codes nor studies have taken this effect into account. This paper is intended to investigate the wind suction effect and its influence on the static wind-resistant behavior of stiffened steel truss bridges during construction. Two wind tunnel tests, including a high-frequency base balance (H-FBB) test and a synchronous multi-pressure sensing system (SM-PSS) test, were carried out with the world's longest arch-stiffened steel truss bridge as a model. On the basis of the experimental results, two net pressure coefficients which could be used to determine the wind suction are proposed. A finite element analysis considering the wind suction effect is also performed, through which the wind suction influence on the model bridge during erection is obtained.     

基于单元应变模态差的网架结构损伤诊断研究

对具有一定程度损伤的网架结构来说,常规的结构有限元分析或实验模态分析得到的位移模态和频率难以有效地反映结构的损伤状况。为了提高诊断效率与诊断结果的可靠性,根据空间杆系结构的受力特点,利用两节点空间铰接杆单元有限元法,由节点位移模态推导出单元应变模态,提出采用结构损伤前后的单元应变模态差作为网架结构损伤定位的识别指标,并以损伤单元应变模态的差值大小确定损伤程度。通过对一个典型网架结构的数值模拟研究表明:该方法能够在低阶模态条件下,有效识别网架结构不同位置和程度的局部损伤;且在一定噪声水平下具有较强的鲁棒性,适用于实际观测条件下的网架结构损伤定位。     

安装过程中风吸力对大跨加劲钢桁桥的影响

在大跨钢桁桥的安装过程中,为缩短工期,桥面板和钢桁梁常同时施工,这将导致风吸力对桥面板产生影响,从而影响安装过程中含大跨悬臂梁的加劲钢桁桥的抗风性能,因为风吸力与自重共同作用会增大结构响应。然而,现有规范和研究都没有考虑这种影响,故需研究风吸力对安装过程中加劲钢桁桥的抗风静力性能的影响。以世界最长的拱加劲钢桁桥为模型,进行2个风洞试验:高频底座天平试验和同步多点压力传感系统试验。基于试验结果,建立2个净压力系数以确定风吸力。通过确定安装过程中风吸力对桥梁的影响,建立了考虑风吸力的有限元模型。     

大跨度铁路站房屋盖结构风洞试验与等效静风荷载研究

以哈尔滨西客站站房屋盖结构为研究对象,采用刚性模型同步测压风洞试验对建筑表面的平均及脉动风荷载进行测定,结合本征正交分解技术对风压场进行重构及预测,解决了风压测点与结构有限元模型节点的不匹配问题。分别建立整体结构和屋盖结构有限元模型,利用时程分析方法考察了下部结构对风致响应的影响,研究表明下部结构会导致屋盖结构的刚度弱化,建模中忽略下部结构可能导致对屋盖结构位移和内力响应的低估。引入多目标等效静风荷载分析方法,以结构在风荷载作用下的最大动力响应为控制指标获得针对多个等效目标的静风荷载分布,并对等效结果进行了验证,结果表明该方法可以实现以少量静风荷载分布形式实现所有响应均与动力极值响应等效。