Restraint of Structures Attached to Mass Concrete

On some massive concrete structures such as dams, comparatively light structural frame s such as trashracks or control appurtenances are extended and built as integral parts of the massive structures. Those structural frames are, in general, exposed to widely varying temperature s imposed by climatic conditions. The varying temperatures induce length changes in the frames. Similarly induced length changes at the surface of the mass concrete between any two points of attachment of the frame must be restrained by the mass, whose range of temperature variation becomes smaller at increasing distances from the surface into the mass. This paper presents measurements of length and temperature changes occurring at depths of up to 5 ft into the masses of three concrete dams in actual service. The measurements were made, periodically, by means of elastic wire strain meters that were embedded in the concrete during construction, and extend over periods of several years after embedment. Based on those measurements, a rational method of calculating the effects of the restraint by the mass concrete is deduced and presented. The method is applicable in design of reinforcement at junctures of massive concrete with comparatively light structural frames where temperature variations are significant.