某海外型钢混凝土井塔结构火灾事故后的评估与加固

Appraisal and Retrofit of an Overseas Composite Shaft Structure after an Fire Accident

根据国内外对钢结构、混凝土火灾后性能分析与鉴定的一般程序、内容及方法,结合某海外型钢混凝土井塔结构的火灾事故,对火灾现场的钢材现场取样拉伸试验及里氏硬度试验;对火灾现场的钢筋现场取样屈服强度、抗拉强度、伸长率试验;对火灾现场的混凝土回弹法、超声波检测、钻芯取样法试验,进一步设计了利用钻芯取样法对混凝土的耐久性检测的试验方法。随后采用测得的相关数据,分析了该火灾后结构材料的力学性能,并与火灾前结构材料的力学性能进行了对比分析。对原结构中钢材节点区域焊缝裂纹进行修复,对不同损伤等级混凝土进行分类处理的维修方案,通过维修保证了结构的强度、稳定性和耐久性等设计要求。此外,对火灾后型钢混凝土的检测鉴定需要注意的问题进行了探讨,对比了中关两国规范钻芯取样法异同点,结合试验,对中国规范钻芯取样法提出了修正意见。

According to general procedures of steel with concrete material appraisal, an overseas composite shaft structure after a fire accident was investigated. Steel materials were studied through tensile tests and the Leeb Hardness. The tensile strength, the yield strength, and the elongation of rebar were obtained by lab tests. The concrete strength was estimated by the ultrasonic-rebound tests, the compressive test of drilling con- crete cores. Concrete durability was studied with these drilling cores as well. With these data, mechanical properties of the structural materials damaged in fire were compared with those from the non-fire area. The cracks at the steel bar welding joints caused by fire were repaired. Different repair schemes were designed for different degrees of concrete. Through retrofit works, strength, stability and durability of the structure were en- sured. Engineering practices of sampling concrete between and US were compared and some suggestions on Chinese codes were proposed.