ANALYSIS OF CONCRETE JOINT MOVEMENTS AND SEASONAL THERMAL STRESSES AT THE CHIANG KAI-SHEK INTERNATIONAL AIRPORT

Abstract: Optical fiber sensors for measuring concrete joint movements were embedded in the concrete slabs during the reconstruction of primary taxiway at Chiang Kai-Shek International Airport since Jan. 2002. Field data have been collected regularly for the first 13 days of concrete curing, and continuously 48 hours per month on a monthly basis. Readings of the sensor 7 demonstrate the joint movements with seasonal temperature changes. It is found that the induced crack occurred four days after joint saw cut and the initial crack width is about 0.29 mm. Concrete slabs shrink during the curing time, mainly due to the drying shrinkage. Joint movement becomes more sensitive to air temperature around two weeks after curing. The slab moves toward joint when air temperature increases from January to June, and backward to its center line from September to January. The measured average moving rate is 0.035 mm per Celsius degree for a 7 m long slab. Due to the limited space at joint, slabs stayed at the closest condition for almost four months, from June to September, with the maximum horizontal compressive stress of 41 kg per square centimeter (586 psi). A prediction model of the readings of joint movement sensor is derived in this study, and the joint movements can be predicted by two regression equations with an average error percentage of 5.8%