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eCurrents - Designing and Building the Future!

A publication of the Lyles College of Engineering at California State University, Fresno

Structures Lab Gets An Upgrade!

The Civil Engineering (CE) structures lab that had been temporarily closed to equip it with new safety features was re-opened in August 2009. In June 2010 additional testing capabilities were completed. After the seismic shaker table that had been fabricated and installed in 2007 had been in operation for about a year, it was realized that some safety features were needed in the lab to safeguard the well-being of personnel and the integrity of the equipment. Steel surrounds were installed around the pressurized pipes, actuator, and accumulator to protect them from falling debris while conducting experiments on the seismic shaker table. 

The steel surrounds for the accumulator and pipes are composed of high-strength steel plate and are bolted to the concrete walls for easy removal for maintenance and test set-up. The cover for the actuator (shown in black behind the red seismic shaker table in the photo) was fabricated from similar steel plate.

To also ensure the safety of the operators and protection of the controller, the controller/computer unit was moved from the testing area into the second floor observation deck from where the operator has a very good view of the testing area while remaining safe.

Several engineering firms had made donations to improve the equipment in the CE laboratories. At the initiative of Michael Jundt and other members of the CE Advisory Board, contributions of engineering firms as well as private donations (matched dollar-for-dollar by the Lyles Gift), made it possible to effect improvements in the laboratories including the structures laboratory. Thus, during the upgrading of the structures lab, and thanks to the creativity and workmanship of Steve Scherer, the CE technician, a new testing unit was recently completed.

The unit consists of a large test frame (foreground in photograph) for flexure, tension, compression and axial testing. The frame can accommodate specimens up 30 feet in length tested in flexure and columns up to 10 feet in height to be tested under axial loading. The test frame can be easily moved within the space in the structures lab to accommodate specimens of different types and sizes.

The test frame is currently equipped with a hydraulic actuator for quasi-static loading up to 50,000 lb tension/compression and 10-in. stroke. The actuator is driven by an MTS pump with 3,000 psi hydraulic pressure with adjustable flow valves. The unit is connected to an automatic electronic data acquisition system with 10 channels for strain gauge, load cell, and extensometer readings. Plans for future enhancements call for the replacement of the current quasi-static actuator with a dynamic, computer-controlled actuator with the same load and displacement capacities as the current one but with dynamic capabilities for testing under repetitive and variable loading.

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