压弯复杂应力下焊趾局部应力一应变研究

通过对模拟结合壳典型部位的焊接试件进行加载试验,分析了压应力对局部应力应变特征的影响,结果显示,焊趾处名义应力相同条件下,局部应力应变值与施加的载荷形式有关．同时,对此试件进行的弹塑性有限元分析,得到了与试验结果基本吻合的规律．由此得出,压应力与弯曲应力的比值较小时,对焊趾处局部应力应变产生的影响可忽略;比值较大时,产生的影响不可忽略．     

设置级配碎石基层沥青路面结构力学分析

以沥青路面路基顶面压应变、路表弯沉为研究指标,使用Bisar3.0软件分析了级配碎石基层厚度与模量及土基模量变化对这两种指标的影响,可供同行参考。     

闭口肋加劲板屈曲临界应力计算方法

采用能量法,推导了单向均匀受压四边简支闭口肋加劲板屈曲临界应力计算方法,考虑加劲肋扭转刚度的影响,按照截面实际形心位置计算了加劲肋和母板的抗弯刚度。以苏通大桥钢箱梁中采用的梯形闭口肋加劲板为例,采用Timoshenko方法、小西一郎方法、板壳有限元法及提出的能量法进行了屈曲临界应力比较。分析结果表明：加劲板长宽比口小于1时,Timoshenko方法和小西一郎方法计算的临界应力与钢材屈服强度比值A大于能量法计算值;口在1～6之间时,Timoshenko方法和小西一郎方法计算的A值小于能量法计算值;口在3～6之间时,能量法计算值与有限元分析结果最接近,偏差在9％～25％之间。可见,采用能量法进行正交异性钢箱梁顶、底板弹性稳定分析可行。     

桥梁基桩完整性检测技术研究

主要对反射波低应变法检测基桩完整性的原理及在基桩检测中的应用进行了探讨,结合工程实例,对检测结果进行分析和判断,可供同行参考。     

汽车车架纵梁焊接变形预测

采用固有应变有限元法,通过一次弹性有限元计算,即可得到整个焊接结构件的残余应力及变形。同时,针对汽车纵梁部分直线段模型进行焊接变形分析,并与试验数据进行了对比,验证了该方法的有效性。在此基础上较准确地预测了某汽车车架纵梁的焊接变形。     

低应变动测在桩基检测中的应用

结合工程实践,从低应变动测的基本原理、现场测试、结果分析以及影响因素等方面介绍低应变动测在桩基检测中的应用。     

基于温度效应的隧道二次衬砌混凝土结构力学状态分析

为了研究寒冷地区隧道二次衬砌混凝土结构在环境温度变化情况下的力学状态,基于振弦式混凝土应变计的测试原理,提出温差引起的误差修正公式,并采用数值模拟的方法,对隧道二次衬砌混凝土的温度应力进行了分析。结合陕西省吴堡至子洲段高速公路刘家坪3号隧道现场二次衬砌混凝土应变监测数据,研究了1年内环境温度变化情况下隧道二次衬砌混凝土的结构受力。结果表明:在温度的影响下,混凝土内部在冬季产生了比较大的拉应力,混凝土内侧拱顶产生压应力,其余部位内侧产生拉应力;混凝土外侧拱顶和边墙部位产生了比较大的拉应力,最大值出现在拱顶部位;混凝土的内外侧应力最大值为1.01 MPa,接近C25混凝土的设计抗拉强度1.33 MPa。     

船舶轻围壁结构的间断焊和单面连续焊变形仿真

针对船舶上层建筑典型薄板轻围壁结构,对间断焊焊接方式和单面连续焊焊接方式进行有限元仿真。在相同的工艺参数下,对2种焊接方式对轻围壁结构焊接变形的影响进行对比。结果表明,2种焊接方式均使轻围壁结构自由边发生翘曲,与实际施工情况相符。依据焊接变形数据得出结论,间断焊有利于对轻围壁结构焊接变形的控制。     

Modeling and analysis of thin-walled Al/steel explosion welded transition joints for shipbuilding applications

The study presents an analysis of S355J2+N steel and AA5083 aluminum alloy welded structural joints using explosion welded transition joints of reduced thickness. The transition joint thickness reduction significantly hinders the welding of the joints due to the risk of damage to the Al/steel interface as a result of the high temperatures during welding. Numerical modeling of the welding process is performed to determine safe welding parameters for the transition joint. The numerical analysis is supported by measurements of the temperature areas by a thermographic method. Welded structural joints are analyzed to determine the welding influence on the mechanical properties and microstructure of the transition joints. On this basis, a number of tests are carried out, including microhardness distribution measurements, strength tests of joints in two welding configurations and strength tests of the microspecimens of transition joints. Moreover, an experimental and numerical analysis of strain and stress distributions is carried out in combination with the use of the finite element method and digital image correlation, which allow us to identify the critical areas of the joints with regards to their strength. The results of the microstructural and strength tests carried out using macro- and microspecimens show softening of the aluminum alloy layers. However, the AA5083 and AA1050 layer softening as a result of welding did not reduce the load capacity of the transition joints, which could determine the strength of the dissimilar Al/steel welded structural joints.     

Seismic Dynamic Response of an Atrium-type Subway Station北大核心CSCD

Atrium-type subway stations have been utilized for multifunctional demands. For natural lighting, the middle parts of slabs are replaced by beams. And to expand space, no columns are set for the 1st floor underground, while flat columns are set for the 2nd floor. These characteristics make the seismic response of the atrium-type subway station differ from the traditional station. In this paper, by a shaking table test of soil-structure 1/30 scale model of the atrium-type subway station, the amplification and attenuation effect of soils to the ground motion, as well as the acceleration and the strain response of the structure are analyzed when the model is subjected to lateral ground motions with different PGA and frequency contents. Subsequently, the seismic dynamic effect on the structural internal force distribution is discussed to improve the seismic design of the atrium-type subway station. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.