Structural behaviors of steel roof truss exposed to pool fire

Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.

Lessons from the seismic behavior of a steel grid roof structure heavily damaged in Lushan earthquake

The seismic behavior of a school gymnasium, whose steel grid roof was heavily damaged during the Mw6.6 Lushan earthquake in 2013, is simulated through nonlinear dynamic analysis. The simulated damage is compared with field observations to validate the numerical model, based on which a parametric study was performed to provide insight into the failure process and damage patterns of steel grids. The results suggest that the grid damage is strongly related to roofsubstructure interactions. These include not only the substructure's amplification of the vibration, but the uncoordinated displacement of the substructure's columns which support the grid also play an equally important role. In particular, the latter effect may significantly alter the internal force distribution in the steel grid and lead to unexpected buckling of members that are proportioned as tension-only members. While such interactions are generally not accounted for in the design practice for grid structures in China, similar seismic damage may be expected for other existing grid roofs in future earthquakes. As is also demonstrated in this study, seismic isolation of the roof is a promising solution to protect grid roof structures by mitigating the detrimental effects of roof-substructure interactions.

Characteristics of wind pressure pulse on large-span flat roofs

The wind pressure pulse events, among the most important characteristics of wind pressure fluctuations on large-span flat roofs, were investigated by wind tunnel tests in this paper. Incorporating the formation mechanism of wind pressure pulse events, the peak over threshold method was employed to study properties of this kind of events. The event duration time, the energy contribution, the number of the pulse events, and the distribution of average peak pressure were calculated. Probability density functions of some typical samples in separation region were also given. Results show that the non-Gaussian roof pressure is strong in the flow separation region owing to the wind pressure pulse events. Evaluations of the extreme peak pressures, which can be determined by the peak over threshold method effectively, are important to the design of building cladding.

Proposal of Stainless Steel Roof Structure and Tiles for Gymnasiums

This work proposed an architectural alternative project of a stainless steel roof structure that uses roof tiles also in stainless steel with emphasis on roofs for multi-sport gymnasiums.In the development of the work,two existing multi-sports gymnasiums are taken as a reference,but with ASTM(American Society for Testing and Materials)A36 steel roof structure.The proposed cover system uses cables and light gauge profiles,in commercial stainless steel,which reduces the weight and of course the final price of the roof structure.A structure that presents technical feasibility is obtained and analyzed by checking its behavior with respect to the efforts and displacements generated by the combinations of the acting loads,following the safety recommendations of the applicable standard.It is verified that using the stainless steel structure proposed in this work would cost 42%of the reference structure if this were in AISI(American Iron and Steel Institute)304 stainless steel.And this cost tends to be minimized due to greater durability and consequent reduction in maintenance costs of this type of steel.

Slotted Hole Effect on Damage Mechanism of Gymnasium Building with RC Frame and Steel Roof

On the 2011 off the Pacific Coast of Tohoku Earthquake, gymnasium buildings exhibited the unexpected structural damages, which prevented a use as evacuation shelters in during- and post-disaster periods. The major failure occurring on the connection between the RC column top and steel roof as well as the cracks in the RC column base was observed during the emergent inspection. According to the earlier studies, it was implied that the presence of the slotted hole possibly deteriorates the seismic capacity;however, the length of slotted hole was fixed at a certain value. Facing this concern, this research attempts to clarify the influence of the slotted hole length through a comprehensive parametric study by pushover and seismic response analyses. In conclusion, it has been discovered that the slotted hole deteriorates the seismic capacity for the connection failure up to almost 50% of that without slotted hole. Moreover, the discrepancy of characteristics obtained by the static and dynamic analyses is originated by means of the presence of slotted hole. This slotted hole effect should be noted by structural engineers and researchers to provide the adequate seismic diagnosis and strengthening.

台风作用下轻钢屋面自攻钉节点的静力-疲劳统一设计模型

对已受疲劳损伤的V125型屋面板自攻钉节点进行静力拉伸试验,获得该类节点在不同幅值疲劳加载作用后的剩余承载力,并分析其在受静载作用下的损伤演化过程,提出了风致疲劳作用下的承载力折减及退化系数计算方法,建立了静力-疲劳统一设计模型.根据实验结果,推导拟合了风速与风致疲劳折减系数的相关关系.根据我国沿海11个城市的台风风速概率信息,给出了适用于相应城市的V125型自攻钉节点的静力-疲劳承载力退化模型.结果表明:V125型自攻钉节点的疲劳极限为其静力极限承载力的20%;在风致疲劳作用下,中国台北的轻钢屋面自攻钉节点的疲劳损伤折减系数最大,上海地区自攻钉节点的疲劳损伤折减系数最小.

水滴形大跨钢屋盖结构风洞试验和风振分析

自然风经过大跨结构时,由于结构屋顶形状不规则,通常会引起柔性屋面的振动,因此针对大跨屋面结构抗风设计需要考虑风压分布和风振响应。以陕西省水务集团矿泉水生产车间为工程背景,制作了1∶200的刚性模型,通过刚性模型风洞试验测得该水滴型大跨钢屋盖结构的表面风压,研究了屋盖表面典型测点及整体的风压分布规律。基于风洞试验数据,对结构进行风振时程分析,得到了屋盖表面的风振响应和风振系数。结合刚性模型风洞试验和风振分析,深入研究了水滴形大跨屋盖结构的风压分布规律和风致振动特性,并总结了其共性规律。

轮辐式索承网格屋盖钢结构单道胎架施工技术

泰安体育场作为山东省泰安市的新地标,其钢结构屋盖采用轮辐式索承网格结构,通过68榀径向索和1道中央环索形成张拉结构体系,最大悬挑跨度为45 m。通过数值分析对施工过程进行了精细化稳定性分析,针对不规则构件吊装的工程技术难点,进行了吊装方案的设计与优化;考虑到成本控制与施工周期,极具创新性地采用了径向单道胎架作为屋盖施工过程中的临时支撑,结合工程实际情况设计了胎架转换结构,并对单道胎架整体在多种可能的荷载组合作用下进行验算与校核。通过对体育场屋盖施工全过程的模拟以及对安装过程中的重难点进行优化分析,为现场施工的安全顺利开展提供了技术保障,可为其他类似采用单道胎架施工方法的工程提供施工方案设计的新思路。

隧道管棚支护承载特性及支护参数试验研究

为探究隧道管棚注浆钢管不同支护参数对管棚支护承载能力的影响,引入Pasternak双参数模型构建出更符合实际情况的管棚支护力学模型,通过多组室内试验,对管棚在不同注浆钢管管径、壁厚、注浆饱满度及加设钢筋笼条件下的承载能力进行定量研究。研究表明:1)管棚注浆钢管支护参数中,对管棚承载能力的影响排序为:管径>注浆饱满度>壁厚>钢筋笼。2)增大管棚注浆钢管管径可大幅提高管棚的承载能力,相比管径为108 mm的管棚,管径为159、219、299 mm时管棚承载能力分别增大183.58%、398.62%、874.86%。3)管棚钢管注浆不饱满会较大程度削弱管棚的承载能力,钢管注浆饱满度由100%降至75%、50%时,管棚承载能力分别降低29.8%、34.5%,注浆饱满度为50%时管棚的承载能力与未注浆时相差不大。4)管棚钢管壁厚和钢筋笼加设与否对管棚的承载能力影响较小。因此,在实际工程中,可通过增大管棚钢管管径提升管棚的承载能力,通过减小管棚钢管壁厚及不加设钢筋笼节约用钢量。

杭州电竞中心车辐式索承网格屋盖结构设计

索承网格结构是一种新型空间结构形式,广泛应用于大跨度空间结构中。针对杭州电竞中心车辐式索承网格屋盖结构进行分析和设计,采用MIDAS有限元软件进行索张拉施工方案设计与仿真,采用ABAQUS有限元软件进行稳定性分析和大震动力弹塑性分析。分析结果表明:在施工过程各个阶段,屋盖钢结构构件应力比始终小于1,索拉力小于索破断力的30%;施工完成时,与设计值相比,屋盖结构最大竖向位移和索内拉力的误差分别为6%和4%;屋盖结构稳定安全系数为9.63,单层网壳结构稳定安全系数为31.2,均大于规范规定的2.0,屋盖结构稳定性满足要求;初始缺陷对本工程单层网壳的影响很小;在大震作用下,屋盖结构构件均未出现塑性变形,且预应力拉索不退张。

地下室顶板车行荷载简化计算及补强方法探索

通过调查分析施工荷载特性和地下室顶板极限承载力影响因素,利用荷载规范研究结论,简化地下室顶板车行荷载对顶板结构受力影响的计算方法,并以兰州市某高校公寓楼地下室顶板为研究对象进行实体验证。在顶板荷载设计基础上,通过顶板增加覆土、利用地下室顶板未拆除的钢管架支撑等措施,作为施工临时道路,可满足施工阶段施工车辆满载行车需要。在此基础上,综合分析评估了地下室顶板采取覆土及加固措施可行性及注意事项,为其它工程的后期建设施工提供了合理的计算方法和评估依据。

襄阳东站柱分叉铸钢节点缩尺模型试验研究

襄阳东站在南、北两端区域采用柱分叉支承钢屋盖以减小屋盖悬挑长度,柱分叉节点考虑到建筑美观要求及受力复杂等因素采用了铸钢节点型式,论文对柱分叉铸钢节点进行了1/2缩尺模型加载试验验证,详细介绍了试验加载装置、加载方案、试验现象及试验结果,有限元对比分析结果与加载试验吻合较好,结果表明柱分叉铸钢节点构造合理、承载力高,薄弱部位出现在与铸钢件相连的接长钢管上,满足强节点弱构件、强连接弱构件的设计要求。

襄阳东站钢屋盖超多杆连接节点设计与足尺模型试验研究

襄阳东站屋盖南北向长358m,东西向最大跨度86m,采用焊接球钢网架,整体不设变形缝,南端开设瀑布造型大洞口,由于屋盖结构超长、不连续、大悬挑及瀑布造型使得钢屋盖空间受力十分复杂,特在分叉柱柱顶沿南北向设置加强杆以加强屋盖瀑布区洞口两侧边缘约束刚度及改善结构整体受力性能。钢屋盖瀑布区悬挑端分叉柱柱顶节点相连杆件达12根之多,该节点作为屋盖结构的关键节点,其受力状态尤为复杂,创新地采用了半铸造半相贯焊连接形式并采取了构造加强措施,针对该超多杆连接节点进行了足尺模型加载试验验证,详细介绍了试验加载装置、加载方案、试验现象及试验结果,并进行了有限元对比分析。结果表明有限元对比分析结果与加载试验吻合较好;该超多杆半铸造半相贯焊连接节点构造合理、承载力高,薄弱部位出现在与铸造本体相连的接长钢管上,满足强节点弱构件、强连接弱构件的设计要求。

重庆江北机场T3B航站楼大厅屋盖钢结构提升施工技术

重庆江北机场T3B航站楼大厅屋盖钢结构为异形三维曲面造型焊接球网架。由于周边飞机不停航,且由于构造复杂、结构高差大、跨度大、杆件数量多,给屋盖钢结构施工带来很大挑战。基于方案探讨和专家论证,提出一种优化施工方案:大厅钢屋盖划为7个提升分区,每个分区在楼面拼装为提升小分块,通过二次及多次累积提升进行施工。施工前运用BIM技术进行工序预演,并采用3D3S,MIDAS Gen软件进行数值模拟分析,为施工的准确性和安全性提供有力支撑。

广州南沙国际金融论坛永久会址主体结构设计

广州南沙国际金融论坛永久会址属于大型复杂会议类建筑,具有大底盘双塔、钢屋盖连体、大开洞、竖向质心偏移、大跨结构等多项不规则项。介绍了结构重力体系和抗侧体系的选型思路,主体结构选用混凝土框架+屈曲约束支撑体系,外表皮采用空间钢结构。重点分析了单塔与整体结构的差异以及钢屋盖对下部双塔的影响。通过弹塑性分析,对大震作用下各个时程点的损伤水平进行评估,对大开洞的楼板进行了地震及温度作用下的楼板应力分析;对大跨桁架进行了抗连续倒塌分析。结果表明结构可满足大震不倒的要求,支撑承载力能充分发挥,大底盘结构具有良好的基座支撑特性。

西安咸阳国际机场T5航站楼钢屋盖旋转提升施工技术

西安咸阳国际机场T5航站楼钢屋盖采用大跨异形空间网架结构体系,结构造型独特,场地条件复杂,工期紧,施工难度大,质量要求高。介绍项目施工的重难点及方案选择,同时对施工过程中涉及的关键技术进行重点说明,主要包括异速等比同步旋转提升施工技术、大面积异形网架屋盖提升措施、旋转提升分区檩托及马道安装定位技术、全过程施工模拟计算分析技术、施工健康监测技术等。

厦门翔安国际机场航站楼三重檐屋盖提升施工技术

在厦门翔安国际机场航站楼建设项目中,屋盖钢结构分上中下3层,上下重叠部分面积大、屋檐高,施工难度大。综合土建施工工艺、施工场地条件、工期等要求,选用满堂脚手架进行安装,并将上层屋檐与船形桁架相连。为保证整体稳定性和施工精度,上层屋檐采用液压提升,中层、下层屋檐安装选用分块吊装或全部分块液压提升方案,控制结构稳定提升。在保证安装质量和精度的前提下,减少施工成本、缩短工期。

中国海洋大学船形钢结构及采光顶施工关键技术

介绍了中国海洋大学海洋科教创新园区(西海岸校区)一期工程船形钢结构及采光顶的施工方案,解决了钢结构安装复杂的技术难题,并取得了速度快、质量好、低消耗的效果。通过有限元分析,得到了每步张拉的钢索张拉力大小,为实际张拉提供理论依据。合理的张拉顺序和适当的工具选择确保了安装的顺利进行。经过船形钢结构安装及吊索张拉、采光顶安装及吊索张拉、船形钢结构稳定索张拉等步骤,最终实现了预期的结构状态。该施工技术具有可行性和可靠性。

预应力倒三角管桁架钢屋盖滑移施工技术

广交会展馆四期展馆扩建工程地处城市核心区,环境复杂,铁、隧、馆多重结构交互。工程体量大,结构复杂,施工难度大,总工期仅644d,在同类工程中工期最短,工期履约压力大。其中展厅屋盖钢结构为预应力倒三角管桁架结构,钢构体量大。针对此屋盖钢结构特点、难点,从缩短工期、高效建造方面开展研究,创新提出超长大跨度钢桁架分段等节奏滑移施工技术,即展馆两侧附属混凝土结构先行施工,提供滑移支撑体系,屋盖钢结构滑移与展厅下部2层主体混凝土结构同步施工,实现了展厅屋盖钢结构提前插入安装,各专业平面、立面穿插施工,缩短了关键线路工期;研发了基于装配式、自稳定高空平台的大跨度钢桁架拼装技术,实现超长大跨度重型钢桁架分单元快速拼装;针对主体结构作为滑移支撑体系两侧异标高的特点,设计双向滑移轨道,并研制滚针式滑靴及动力系统,确保滑移安全稳定;应用倒三角预应力钢绞线快速穿束和张拉技术,解决了超长预应力筋穿束张拉与高空滑移技术难题;液压同步控制系统与智能施工监测确保了大跨超重钢桁架屋盖滑移的应力、应变可控,按方案模拟过程平稳进行。

大型国际航站楼异形双曲金属屋面系统施工研究

以杭州萧山国际机场三期项目新建T4航站楼为例,研究了超大面积异形双曲钢结构金属屋面系统、不锈钢天沟系统、天窗系统、不锈钢防坠落系统和防雷系统施工工艺及施工关键技术,提炼总结形成超大面积异形双曲金属屋面施工成套技术,实现了各系统的精准安装,为后续大型会议会展场馆和机场类超大型建筑金属屋面施工提供可借鉴经验。