CONTROL AND MONITORING OF TEMPERATURE CRACKS OF BASEMENT WALL FOR SHANGHAI SCIENCE MUSEUM

In the project of Shanghai Science Museum,the pre-stressing technology was used to control the cracking of the arc shaped ultra-long basement wall.The steel string type steel bar taseometer was installed in the wall in advance to examine the pre-stressing value.The measurement of the change of the pre-stressing value in the wall was lasted for eight month.The results indicated that the pre-stressing exerted on the wall has met the designed requirements.The changing of the pre-stressing value displays certain regularity in the time and the space.In the time,the performance is,the pre-stressing value of identical measuring point is firstly increasing gradually along with the time,finally tends to stability.In the space,the performance is: verticaly,in the wall,the pre-stressing value is small nearby the basement roof,then it will become the biggest at a place with some distance away from the basement roof,after that,it will reduce gradually.In crosswise,the pre-stressing value is biggest in both the tensile ends,it will then reduce gradually to the middle of the wall.Meanwhile,the crack monitoring instrument was used to monitor the cracks,the result showed that the concrete crack quantity and the scale finally were under control.The practice indicated that the pre-stressing technology is an ideal method to control the cracks of ultra-long concrete structures.