大轴重列车对既有线32m预应力混凝土简支T梁的疲劳影响研究

以朔黄铁路为工程背景,从疲劳抗裂的角度对列车轴重250 kN、280 kN、300 kN、330 kN、350 kN、400 kN情况下,对朔黄铁路32 m正常高度预应力混凝土简支T梁的疲劳抗裂性进行分析。通过正截面疲劳应力分析可知:1250 kN轴重时,梁体在循环次数达500万次左右才会出现消压,1 800万次左右开裂;2280 kN轴重时,梁体在循环次数达150万次左右就会出现消压,800万次左右开裂;3300 kN轴重时,梁体在循环次数达51万次左右已开始消压,450万次左右开裂;4330 kN轴重时,梁体在循环次数达3万次左右已开始消压,150万次左右开裂;5350 kN轴重时,梁体在循环次数达1000次左右就开始消压,59万次左右开裂;6400 kN轴重时,梁体在循环次数达100次左右已出现开裂。因此,既有朔黄铁路重载运输的列车轴重从23t提高到300 kN是较为适宜的。

Study on the Effect of Fatigue in 32 m-span PC Simply Supported T-type Beams on Existing Line Due to Heavy-haul Transport

Based on Shuo-Huang railway engineering,an analysis of fatigue crack resistance is conducted on 32 m-span PC normal-height simply supported T-type beam under 250 kN,280 kN,300 kN,330 kN,350 kN,400 kN axle load. The analysis of fatigue stress of right section shows that 1under 250 kN axleloads,the bottom flange of the beam can be of decompression with about 5. 00 million cycles and cracked about 18. 00 million; 2under 280 kN axle loads,the bottom flange of the beam can be of decompression with about 1. 5 million cycles and cracked about 8. 00 million; 3under 300 kN axle loads,the bottom flange of the beam can be of decompression with about 4. 50 million cycles and cracked about 0. 51million; 4 under 33 t axle loads,the bottom flange of the beam can be of decompression with about 0. 03 million cycles and cracked about 1. 50 million; 5 under 35 t axle loads,the bottom flange of the beam can be of decompression with about 1000 cycles and cracked about 0. 59 million; 6under 400 kN axle loads,the bottom flange of the beam can be cracked with about 100 cycles. Therefore,it is appropriate that the axle-load of heavy-haul transport on the existing Shuo-Huang railway line is increased from current 230 kN to 300 kN.