Sensitive factors research for track-bridge interaction of Long-span X-style steel-box arch bridge on high-speed railway

X-style arch bridge on high-speed railways （HSR） is one kind of complicated long-span structure, and the track-bridge interaction is essential to ensure the safety and smoothness of HSR. Taking an X-style steel-box arch bridge with a main span of 450 m on HSR under construction for example, a new integrative mechanic model of rail-stringer-cross beam-suspender- pier-foundation coupling system was established, adopting the nonlinear spring element simulating the longitudinal resistance between track and bridge. The transmission law of continuous welded rail （CWR） on the X-style arch bridge was researched, and comparative study was carried out to discuss the influence of several sensitive factors, such as the temperature load case, the longitudinal resistance model, the scheme of longitudinal restraint conditions, the introverted inclination of arch rib, the stiffness of pier and abutment and the location of the rail expansion device. Calculating results indicate that the longitudinal resistance has a significant impact upon the longitudinal forces of CWR on this kind of bridge, while the arch rib＇s inclination has little effect. Besides, temperature variation of arch ribs and suspenders should be taken into account in the calculation. Selecting the restraint system without longitudinally-fixed bearing and setting the rail expansion devices on both ends are more reasonable.     

电采暖:数据释放的多重诱惑——公主岭示范实例的放大观察

正吉林省长春市区西南50公里便是公主岭。约300年前,清帝乾隆第三女下嫁蒙古王公,奉敕此地,使这个冬季苦寒之地首次扬名。今天,公主岭市引发业界关注的是电采暖推广活动。尤其在雾霾已经成为东西南北"伤不起"的心痛背景下,公主岭鼓励城乡居民采用电采暖方式的初衷和作为,更是为寒冷地区如何通过实现革命性的取暖方式替代升级,提供了有价值的论证实例。调查的初步结论是,公主岭的探索在政府、供电企业、设备厂商和用户等多个关联方中已经达成了共识,同时显示出带有趋势性的潜力。     

特高压价值再认识：助电工装备制造业重生

11月21日，烟雨朦胧的成都，在中国电机工程学会、英大传媒投资集团有限公司联合主办的特高压设备制造及应用高峰论坛上，我们发现，特高压不再如登山一般负重前行，不再是暗夜中孤独寻路；它已站上高峰，向更广泛的领域普惠技术与经验；它已拥有一大批追随者和鼓劲者，推动着它继续向前。     

动载下CRTSⅡ型无砟轨道-简支梁桥变形试验研究

为了研究动载下CRTSⅡ型无砟轨道简支梁桥的变形特征,以现场试验为依托,测试了CRH380A-001型列车以速度240~350 km/h通过纵连板式无砟轨道32 m简支梁桥时梁轨系统的结构变形。通过现场采集和数据分析,得到了桥梁结构的竖横向绝对位移、水平折角及梁端转角,轨道结构的竖横向相对位移和墩梁纵横向相对位移,研究了桥梁的共振速度及动力系数。结果表明:动载下梁体竖向跨挠比最小值为54 000,水平跨挠比最小值为150 000,远大于规范规定最小限值;梁体梁端转角最大值为0.077‰,水平折角最大值为0.119‰,满足规范限值;实测CRTSⅡ型无砟轨道32 m简支梁桥存在二阶竖向共振速度306 km/h及三阶横向共振速度312 km/h,分别与理论共振速度309 km/h和315km/h相吻合;在共振速度附近实测动力系数大于规范规定取值1.084,且最大值达1.18。     

Numerical calculation on solar temperature field of a cable-stayed bridge with U-shaped section on high-speed railway

Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.