大跨度桁架式钢吊车梁下弦整体式节点的承载力和疲劳性能

本文对大跨度焊接重型桁架式钢吊车梁(杆件均为焊接H型钢截面)的整体式节点的静力及疲劳试验结果进行了系统的分析和总结,分析了节点上应力分布状态、节点疲劳破坏位置,探讨了节点的承载力和疲劳强度。节点的分析计算用有限单元法,采用空间平面应力薄膜单元,同时还考虑了材料的塑性性能,得出在荷载作用下节点板中塑性区的分布规律和节点的极限承载力。最后归纳提出了节点的静力强度和疲劳强度。     

大跨度钢-混凝土组合桁架铁路桥端节点模型试验研究

钢-混凝土组合桁架梁上弦端节点受力复杂,有必要通过模型试验对其钢-混上弦节点的应力应变状态及工作性能进行研究,探索组合桁架上弦节点合理构造和承载力。介绍节点模型的设计、加载过程和测点布置等;重点通过对试验结果分析和有限元计算的比较,得出弦杆应变和节点板应力的分布规律,通过绘制弦杆荷载-水平位移曲线,对节点的非线性受力行为进行研究,得出节点整体的受力性能。研究表明:钢-混凝土组合桁架节点受力合理,节点承载力安全储备较高,满足铁路桥梁设计要求,PBL连接件抗剪能力良好;节点板是受力的关键部位,加设节点板加劲肋可以有效提高节点屈服后强度,但对极限荷载的提高作用不大。     

钢吊车梁疲劳设计可靠指标及分项系数研究

定义了钢结构疲劳失效极限状态,基于已有的对钢吊车梁的研究和现场对中级工作制钢吊车梁的疲劳荷载效应实测,分析了疲劳强度和疲劳荷载效应的统计参数,应用一次二阶矩方法计算了疲劳可靠指标,研究了疲劳可靠度设计分项系数的取值。研究结果表明:钢吊车梁中12类细部构造(含应力比影响)的疲劳强度标准差取值范围在0.025 1~0.079 2之间,当等效应力幅服从对数正态分布时,等效应力幅的标准差为0.014 8。为此,建议疲劳可靠指标取值2.9,疲劳强度分项系数取值1.0,疲劳荷载效应分项系数取值1.14。     

全T型钢桁架承载力及节点性能的试验研究

通过对两种节点形式下的全T型钢桁架承载力的试验研究,分析桁架承载力的理论计算依据,并借助有限元分析软件对桁架节点进行应力分析。对试验值与有限元计算值进行对比,验证有限元软件分析全T型钢节点的适用条件,分析节点的受力性能的特征及优越性,为推广T型钢在桁架中的应用提供依据。     

直角突变式支座薄腹钢吊车梁疲劳性能评估与加固技术研究

设直角突变式支座的薄腹钢吊车梁，在吊车荷载作用下，腹板平面外变形产生的弯曲应力导致吊车梁腹板的疲劳性能明显降低。实际工程中的直角突变式支座薄腹吊车梁，在插入板端部位置的腹板沿竖向产生疲劳裂纹，裂纹长度最大达到300 mm,继续开裂会严重威胁生产安全。通过实测开裂的直角突变式支座薄腹吊车梁的动态应力、欠载效应的等效系数及平面外动态变形，得出吊车运行频繁程度和插入板端部切角弧度是影响插入板端部位置腹板疲劳强度的关键因素。采用有限元法和疲劳裂纹扩展分析技术，对直角式突变支座薄腹吊车梁插入板端部的腹板开展了拟静态疲劳裂纹扩展模拟，得出裂纹长度与应力强度因子的关系曲线。提出了适用于直角突变式支座薄腹吊车梁的钢板高强螺栓加固和“贝壳板”焊接加固两种加固方法，并对比分析了两种加固方法的有效性。证明钢板高强螺栓加固和“贝壳板”焊接加固均可有效降低裂纹尖端的应力强度因子，提高直角突变式支座薄腹钢吊车梁疲劳强度。     

T形钢桁架连接节点分析

本文主要介绍T形钢桁架的特点,指出分析桁架节点的意义,对规范中没有提出计算方法的此类连接节点进行分析。重点对T形钢桁架的上弦节点进行探讨,提出了一种节点的简化模型计算方法,采用ANSYS软件进行有限元分析,通过节点的mises应力云图和位移变形图,了解节点在不同荷载作用下的应力分布规律,找出节点受力中最不利的环节,分析节点的受力特性,提出了相应的解决办法,特别是节点设计中的一些构造措施,可以为设计人员在节点设计时提供一些参考。     

鄂尔多斯体育场转换桁架节点试验研究

为考察鄂尔多斯体育场钢屋盖转换桁架节点在设计荷载下的受力性能,对该钢桁架上、下弦的两个节点进行了缩尺试验研究。试验表明上、下弦节点在设计荷载下均未发生破坏,节点整体仍处于弹性状态,大部分区域的应力水平较低,下弦节点的最终破坏模式为受压杆件及相连节点板的局部屈曲。随后建立了考虑材料和几何非线性的有限元模型,计算结果与试验中的测点数据吻合良好。试验和有限元的分析结果均表明,鄂尔多斯体育场钢桁架上下弦节点在设计荷载下具有足够的刚度和强度,满足工程应用的要求。     

敞开式连续钢桁架节点设计与分析——以赣州螺溪洲大桥为例

常规钢桁架桥梁上部存在较多的横联及平联,影响桥梁的通透性及景观效果,而敞开式钢桁架桥能较好解决这一问题,使其在城市桥梁中得到更广泛应用。以赣州螺溪洲大桥为例,对大跨径敞开式钢桁架桥的整体受力性能进行分析。在整体分析基础上,选取受力最不利的隔离体模型进行局部有限元分析。局部模型上部最大等效应力出现在斜腹杆与竖腹杆的节点板连接处,局部模型下部最大等效应力出现在主梁纵向支座加劲肋与横隔板交界处,且应力峰值均小于钢材屈服应力。故应重视大跨径敞开式钢桁架桥节点应力集中部位的设计,也为同类型桥梁的节点设计和分析提供一定参考。     

设有悬挂吊车支座的钢桁架结构设计

通过南亚PU厂房的设计实践 ,对设有吊车梁悬挂支座的钢桁架结构在吊车荷载作用下的内力分析、截面选择、节点设计、变形计算以及支撑布置等进行了介绍和探讨 ,并提出了设计中应注意的几个问题及相应建议。     

重庆江北国际机场新航站楼大跨钢桁架铸钢节点性能研究

本文针对大跨钢桁架铸钢节点受力性能进行了相关的研究。通过重庆江北国际机场新航站楼钢桁架大型铸钢节点的现场跟踪测试,得到铸钢节点表面应力的测试值;利用Pro/E软件建立所测试的铸钢节点模型,并采用有限元软件进行弹性分析,得到各测点的应力值。通过比较铸钢节点表面测试值和相应测点分析值,发现现场测试应力值和计算分析值之间相互印证。在测试值与计算值印证较好情况下,可以推断节点内部应力分布。此外,还模拟了铸钢节点的典型缺陷并进行有限元分析,进而推断铸钢节点带缺陷工作状况对节点的受力性能影响程度。最后对铸钢节点在整个结构体系中的受力性能和安全性做出了评价,重庆江北国际机场新航站楼钢桁架铸钢节点是安全可靠的,具有充足的强度储备;并给出了节点的设计强度取值和判别式,可供类似的工程应用参考。     

Structural performance of composite joints using bent studs

A composite truss bridge is an efficient structural type where the merits of both the steel member and the prestressed concrete member are combined. The design of a connection for the truss bridge is of particular interest due to complex details resulting from concentrated forces at the composite joint. In this paper, experimental investigations were conducted to evaluate the performance of the joint with bent studs welded on a gusset plate. Push-out tests for static and fatigue loadings on a group stud connection were conducted to evaluate the direct shear strength and fatigue endurance of the joint. Because the joints are subject to various loading conditions, flexure-shear tests were also performed to verify the design provisions for the joints under a combination of tension and shear. In order to enhance the structural behavior of the connection, a bent shaped stud was proposed to increase the pull-out strength of the concrete slab. Test results showed that it is adequate to use Eurocode-4 for the evaluation of a shear connection which satisfies the requirement of minimum stud spacing specified in Eurocode-4. Since the shear load is concentrated at the joint structure of composite truss bridges, additional confining reinforcements are needed to enhance the horizontal shear strength of the shear connection. The design provision on the interaction of tension and shear for the joint structure gave conservative results. When the pyramid failure surface was assumed, internal studs had little effect on the pull-out strength of the joint. Constructability of the joint can be enhanced by decreasing the number of connectors and by strengthening the concrete slab through simplified design checks assuming four failure modes and their interactions.     

钢管混凝土桁架新型节点试验研究

对6个圆形钢管节点板式节点和6个钢管混凝土节点板式节点进行了对比试验研究。试验结果表明:空钢管试件在达到极限荷载时,节点板下空钢管发生严重局部屈曲而丧失承载力;钢管混凝土节点则在节点板下只发生轻微局部屈曲现象,具有较高的承载力。相比之下,钢管混凝土的承载力明显高于空钢管的承载力,并具有更好的延性性能。在钢管混凝土桁架中采用节点板式节点可比相贯节点更加方便、可靠。     

子结构技术在钢桁桥疲劳分析中的应用

运用子结构方法,建立钢桁桥的有限元模型,把容易发生疲劳破坏的焊接节点作为子结构凝聚到整体有限元模型中。对结构施加移动荷载,进行瞬态分析。结果表明,子结构方法具有较高的精度,能够反映节点部位的疲劳损伤状况;并且,节省了大量的机时。     

新型组合桁架式吊车梁试验研究

为了解组合桁架式钢吊车梁的受力性能,对9 m跨度的组合桁架式钢吊车梁进行了3次静力试验研究,直观了解了吊车梁的受力性能和破坏机制,并验证了理论分析的正确性。研究表明,组合桁架式钢吊车梁受力最大杆件是下弦受拉杆,竖向腹杆与上弦热轧工字钢焊接节点的刚度和下弦节点的侧向支撑对整个桁架式吊车梁的受力性能影响较大,在设计中要予以充分考虑。     

Study on failure modes of steel truss bridge gusset plates related to tension and shear block failure

Tension and shear block failure is a limit state which occurs in the connection of tension steel members. The failure mechanism is a combination of tensile failure on one plane and shear failure on the perpendicular plane. The design strength equations for the tension and shear block failure are described in the well known design codes. However, they provide inconsistent levels of safety when they are used in different types of connections. In this paper, the authors survey the design strength equations in the various codes. Then, the pertinent strength equations for the gusset plates of steel truss bridges are selected. Moreover, the authors propose a pair of strength equations for compression and shear block failure for gusset plates subjected to compressive force. And to examine the applicability of proposed equations and to investigate the mechanical behavior of compression gusset plates, parametric analyses on the various thicknesses of gusset plates were conducted.     

Fatigue strength improvement of welded joints by blast cleaning for subsequent painting

In the fabrication of steel bridges, prior to painting, blast cleaning is performed to clean the surfaces and to increase the adhesive properties of the surfaces for the subsequent painting. In addition to these objectives, blast cleaning can improve the fatigue strength of welded joints, as a result of the impact of forcibly propelled abrasive materials on the welded joints. A series of fatigue tests were carried out on the five different types of welded joints: one-side out-of-plane gusset fillet welded joints, both-side out-of-plane gusset fillet welded joints, non-load-carrying rib fillet welded cruciform joints, butt welded joints, and a large-scale model beam with out-of-plane gusset welded joints, and under the three different types of load conditions: uniaxial tension, out-of-plane bending, or in-plane bending stress cycles. Drawing on previous fatigue test results that include unpublished data, this paper presents the beneficial effects of blast cleaning for the subsequent painting applications on the fatigue strength improvement of welded joints and also presents a simple quality control method for the blast cleaning process that improves the fatigue strength.     

建筑施工中大型塔吊支撑架的设计及验算

某大型钢结构工程中桩基位置偏离,须安装塔吊转换支撑桁架。为此,进行了塔吊支撑桁架的设计、验算以及ANSYS和MIDAS数值模拟分析,分析转换桁架和塔吊支撑桁架在工作情况和非工作情况下,节点水平位移、杆件应力比,验证其是否满足强度要求以及施工精度要求。通过对某大型钢结构工程中大型塔吊支撑的数值模拟后可知:承载的实际值与数值模拟的理论值相当接近。该方法可在类似大型塔吊支撑架的设计中推广运用。     

Zur Bemessung von Knotenblechen in Stahlfachwerkkonstruktionen

On the design of gusset‐plates in steel‐truss‐constructions. Due to the fact, that it is very complicated to develop a correct estimation of the stresses in gusset‐plates, there is generally no great emphasis on the design process of these elements. On the base of elementary mechanical relations, it is possible to develop a simplified calculation model to determine the relevant forces and moments for the verification of continuouses and slotted gusset‐plates taking fatigue effects not into account. These formulae can be used to establish easy to use design diagrams for the critical cross‐sections of these elements of a truss‐construction.     

空间板节点的非线性分析与极限受压承载力研究

本文提出一种改良的网架节点型式一空间板节点。现行规范中板节点的计算方法多是依据强度条件得出的,而当节点板在轴压作用下,可能在达到屈服强度以前就发生整体失稳,因此有必要对板节点的受力性能进行深入分析,提出相应节点的计算方法。本文采用有限元软件ABAQUS建立板节点数值模拟模型,通过变参数分析考察了节点板厚度和无支长度等因素对节点板受压性能的影响,并将结果与现行规范计算值进行对比分析,提出了单面连接节点板极限受压承载力的计算方法,并对其适用性进行了验证。     

在悬挂吊车作用下螺栓球节点网架的疲劳性能

本文对１２根螺栓球节点网架杆件试件，１２个悬挂吊车吊点试件及两榀螺栓球节点桁架试件进行了静力及疲劳试验。通过对三种试件破坏形式分析得出了：在悬挂吊车荷载作用下，网架杆件、悬挂吊点与螺栓球连接高强螺栓的疲劳断裂是螺栓球节点网架的主要破坏形式，并提出了Ｓ－Ｎ疲劳曲线及表达式．为螺栓球节点网架的疲劳设计及有关规程的修订提供了依据。