Hiroaki NISHIMAKI
Experimental Study on the Behavior of Composite Girder Continuous Clarification with a Composite Slab Subjected to Under Hogging Bending
Masatsugu NAGAI
In order to meet the demand of construction cost reduction, in Japan, the construction of continuous composite girder with high durable slab has been increasing. In recent years, composite girder with composite slab has been recognized as a promising solution for attaining LCC minimum, long life and high durability.
In the design of continuous composite girder bridges, crack width control in the slab at intermediate supports becomes important subject. In this study, we propose crack width control design for composite girder with composite slab based on experimental study. Furthermore, in order to find the possibility of the reduction of the number of shear connectors (headed studs) at intermediate supports, three two-span composite girder test models with different number of headed studs were prepared, which is denoted as CASE-1, CASE-2 and CASE-3. The number of the headed studs was determined based on AASHTO LRFD design code, which gives a smaller number of studs compared to Japanese roadway design code. CASE-1 is full composite action. CASE-2 has no stud at intermediate supports. The stud number in CASE-3 is smaller than that of CASE-1.
From the experimental results, it is known, regardless of the number of the headed studs, that three moles shows the same the load-displacement relation. It means that flexural rigidity will not be affected by the number of the headed studs. It is also known that the bottom steel plate in composite slab contribute the reduction of crack width. In order to take into account of the contribution, we already proposed the design method, in which ¦Ç coefficient giving percentage of the thickness of the bottom steel plate is used. Calculated crack width based on our proposition shows a good agreement with experimental results, when we set ¦Ç value of 0.4 for the CASE-1 and we set from 0.2 to 0.4 for the CASE-2 and CASE -3.
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