STRAIN GAGE ASSEMBLY FOR MEASURING EXCESSIVE TENSILE STRAIN OF A FLEXIBLE ELONGATED MEMBER, SUCH AS A STEEL STRUCTURAL CABLE, OR AN ELECTRICAL TRANSMISSION CABLE, OR A GLASS FIBEROPTIC COMMUNICATION CABLE, WHICH MAY SLIGHTLY TWIST UNDER TENSILE STRAIN

摘要

A strain gage assembly is secured between two initially longitudinal locations on the exterior of a flexible elongated member, such as a steel structural cable, or an electrical transmission cable, or a glass fiber optic communication cable, after or before the installation of the flexible elongated member, to thereafter upon the subsequent pre-stressing and/or the possible excessive straining of the cable, create an observable or transmittable reading of the excess tensile strain being sustained by the flexible elongated member. This strain gage assembly includes, in one embodiment, the in line arrangement of a vibrating wire strain gage, having the vibrating wire thereof secured to a calibrated coiled spring, which in turn is secured to an inner tube shaft, which in turn is telescopingly fitted within an outer tube shaft, that is secured to the vibrating wire strain gage. By using two spaced securement means, such as clamps, this strain gage assembly is secured to the exterior of a flexible elongated member. One securement means secures the combined vibrating wire strain gage and the outer tube shaft to the flexible elongated member at one location. The other securement means secures the combined calibrated coiled spring and the inner tube shaft to the flexible 1 elongated member at a spaced second location. The inner tube slightly radially turns relative to the outer tube, within controlled limits, to compensate, if necessary, for any slight twisting of the flexible elongated member, which may occur when the flexible elongated member is excessively strained in tension. This strain gage assembly, when installed, may also include a thermistor to signal temperature changes, a data transmission means via electrical cable leads of electrical circuits, and/or a signal transmitter means via radio waves, optionally utilizing satellite transmissions or meteor burst transmissions, and/or a protective cover, and/or a vibrating wire readout instrument. When the flexible elongated member is a tieback steel structural cable, for example, the strain gage assembly created reading may be read at random times, at scheduled times, or constantly, during either static or dynamic loading periods of time. Observations may be made before, during, and after earthquakes.