Combined Mechanical and Thermal Loading on Plain and Steel Fibrez Reinforced Concrete Pavements

Paper by ALAVIZADEH from ISCR 8th 1998 Lisbon Portugal

Plaiti aiid steel fibre reinforced concrete beams are subjected to solely thermal; solely mechanical and combined thermal and mechanical loads while the rotation of the beam-ends are prevented. The variables in the tests are type of load and combination of loads. In order to estimate the degree of restraint, some simply supported beams are also tested and the result is compared with the result from restrained tests. Heating the top surface of the test beams provides thermal load, whereas mechanical load is introduced by applying a point load at mid-span of the test beams. The induced thermal gradient, applied mechanical load, strain distribution across the critical sections and vertical and horizontal deformations along the beam are monitored. The main focus is on the analysis of measured load-carrying capacity of test beams when these are subjected to different combination of mechanical and thermal loads. This showed that the superposition of stresses for combined loading gives a satisfactory estimation of the load-carrying capacity. The result also shows that the effect of relaxation of stresses due to short time thermal loads is not noticeable in the achieved load-carrying capacity for combined tests. On the contrary, a tendency for reduction of load-carrying capacity was obseived at higher temperature gradients. In addition, the ductile behaviour of steel fibre reinforced concrete after cracking and release of thermal stresses due to reduction of stiffness are the most important observations in steel fibre reinforced concrete pavement. Using the residual load-carrying capacity of cracked steel fibre reinforced concrete may lead to a reduction of concrete thickness in pavement design.

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