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Wang Gaoxin,Ding Youliang 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.3
Based on health monitoring system installed on steel truss arch girder of Dashengguan Yangtze Bridge, temperature differences from cross sections of top chord, arch rib chord, bottom chord and diagonal web member are specially monitored and researched through extreme value analysis, correlation characteristics analysis and probability statistics analysis. On this basis, yearly extreme values of temperature differences are simulated for the whole service period by combination method of Monte-Carlo simulation and Newton iteration, and furthermore standard values of temperature differences with exceeding probability of 2% are calculated by generalized extreme value distribution function. And main research results reveals that: (1) obvious temperature differences actually exist in the cross sections of chord members and diagonal web member; (2) uniform temperature action actually exists in cross sections of chord members and diagonal web member at night, and temperature differences in the daytime commonly increase under solar radiation; (3) temperature differences from cross sections of top chord, diagonal web member and arch rib chord increase or decrease simultaneously; (4) Weighted sum of three Weibull distribution functions can well describe cumulative probability characteristics of daily extreme samples; (5) generalized extreme value distribution function can well describe cumulative probability characteristics of simulated yearly extreme values, and correlation scatter plots between calculated standard values and monitoring extreme values show good linear relationship.
Thermal Field Characteristic Analysis of Steel Box Girder Based on Long-term Measurement Data
Youliang Ding,Guangdong Zhou,Aiqun Li,Gaoxin Wang 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.2
Thermal loads are important factors that affect the serviceability of long-span bridges. In this paper, the distribution characteristics and statistical features of thermal field in flat steel box girder are presented based on long-term field measurement data collected by the structural health monitoring system (SHMS) permanently installed on the Runyang Suspension Bridge (RSB). Firstly, the daily variations as well as seasonal ones of measurement temperature and temperature differences in the box girder cross-section are summarized. Secondly, employing a combined probability distribution model defined by the weighted sum of one Weibull distribution and one normal distribution, the probability density function (PDF)of each temperature difference is formulated. Thirdly, making use of the extreme value analysis, the extreme temperature differences are predicted with a return period of bridge design working life and compared with the expected values in British standard (BS EN 1991-1-5, 2003). Finally, the critical temperature difference models in cross-section are proposed for thermal stresses calculation according to correlation analysis. The results provide a clear understanding of thermal field in flat steel box girder bridges and have reference values for structural design and evaluation.