[WRE UPDATE | PROJECT]
of the PXI controls a bank of 54 motor contactors occupying the west wall of the control room, which drive the Brametal-supplied winches on the ground. T e control system and software - created specifi cally for Sabre - was developed in LabVIEW software by Cohen, a Certifi ed LabVIEW Developer. Secure Remote Access - a standard on most current Chant systems - is included. Initiated by the client, secure remote access allows Chant engineers to log onto a system remotely, seeing exactly what the operator sees. Diagnostics, system upgrades and even training can be accomplished quickly and effi ciently on any machine with internet access, a huge cost savings for end users. Accurate load readings are essential, with calibration
often required both before and after a test; and the time required to calibrate over 50 load cells can be substantial. Chant’s engineers designed and produced a custom Calibration Station capable of calibrating
COMMISSIONED IN AUGUST, 2013, THE SABRE/BRAMETEL’S NEW STATE-OF- THE-ART, FULL-SCALE STRUCTURE TESTING FACILITY WAS DEVELOPED TO TEST LATTICE TOWERS AND TUBULAR STEEL STRUCTURES UP TO 235’ HIGH.
wind defl ects the structure, joints in the structure slip, and the reaction frame itself fl exes. As a result the loads are continually shifting,
creating a very complex control task. But controlling and maintaining the balance between loads is crucial, especially when loads are near the upper limits of the test. Structures can collapse inadvertently if balance is not maintained properly. Chant’s control system - with its wireless stream of
data provided 8 times a second - is able to monitor, control and maintain balanced loads much faster and more accurately than any human operator could. T e constant tap dance of the motor contactors inside the control room is a constant reminder of the speed of the controller – and the benefi t of automation. T e scale of the test station is enormous. Designed for one full scale test per week, the reaction frame encompassing the test area easily accommodates a lattice tower 235’ high and 85’ wide and can be seen for miles from the highway. T e Brametal-supplied winches are arrayed around the reaction frame according to load direction: 14 for vertical loads are located just south of the test structure, 20 for transverse loads are 250’ to the east and 20 for longitudinal loads are 250’ to the north. To get a sense of the lengths of wire rope in use, trace
fi ve load cells at once to ASTM E4 standards, in a fraction of the time previously required. Rounding out the project was a Chant 100,000 lb. Universal Testing Machine allowing immediate on-site verifi cation of structural material strength. With so many loads applied simultaneously – up to 54 at a time - a structure test is very diff erent from a single-pull proof test. When the structure fl exes, loads applied at one point are transferred throughout the structure; pulling on one point changes the loads at every other point. In addition to this, ropes stretch,
the rope used to apply a single transverse load at the top of a 200’ structure. Off the winch, the rope goes through a series of pulleys increasing the load capacity as need – up to 90,000 lbs. T en 250’ from the winch to a pulley at the base of the reaction frame, 200’ up the frame to another pulley, and then 50’ horizontally to the load cell which is attached to the structure. It is easy to see why Sabre chose to go wireless. With a full complement of load cells on a single structure, some as high as 235’ in the air, management of the hundreds of feet of load cell cables – in addition to the maze of load ropes - becomes a logistical nightmare. Chant’s wireless load cells are weatherproof and designed to withstand constant exposure to the extremes of Alvarado’s climate. In operation for almost a year, the system has been
running fl awlessly, with multiple tests completed and many more to come. ❙
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JULY-AUGUST 2014
WIRE ROPE EXCHANGE
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