Effects of traffic vibration on curing concrete stitch: Part I — test method and control program

When a bridge is widened by constructing a new deck and casting a concrete stitch between the existing deck and the new deck, it is often required to maintain traffic without interruption and as a result the curing concrete stitch would be subjected to traffic induced vibration. A number of experimental investigations had been carried out in the past to study the effects of traffic vibration on curing concrete stitches but widely different results were obtained by different researchers due to the different test methods and equipment used. In fact, in the previous investigations, two important loading conditions have not been properly simulated: (1) the concrete stitch should be subjected to contraflexural loading; and (2) the loading transmitted to the concrete stitch should change as the stiffness of the concrete stitch increases with time. Herein, a new test method that the authors have recently developed for application to several bridge widening projects is presented. In this test method, the above loading conditions are simulated and the applied deflection/loading is real time computer controlled by an impedance dependent control program. The test results so obtained are presented and studied in the accompanying paper (i.e. Part II).