Effect of Uplift Restraint in Wall Racking Tests

摘要

This study was conducted to compare three potential alternatives to the current American Society for Testing and Materials (ASTM) standard wall racking tests, specifically ASTM Standard E 72 holddown device, and to recommend one to be used with ASTM Standard E 564 for testing walls sheathed with gypsum wallboard. A major shortcoming of the ASTM tests is the uplift restraint mechanism which has variable influence on wall racking performance and does not accurately simulate inservice boundary conditions Test results support acceptance of a cable holddown for use with gypsum - sheathed walls and further development of a hinge mechanism as a standard test holddown. The third alternative, a steel strap, was rejected due to test damage making it nonreusable. For immediate application, the cable had advantages over the hinge since it can be easily fabricated, uses readily available materials, and does not require extended testing and development time. Concerns about its possible influence on wall stiffness and strength, however, limit its value to comparative testing rather than establishment of allowable load. The hinge has greater potential for application to a standard test, since it appears to have good test repeatability, can be easily equipped with strain gauges and calibrated to record uplift loads, offers the best resistance to uplift, and has less influence on the racking strength of the wall. A hinge must be designed specifically for wall racking tests, since the stock T hinge used in these tests had some design deficiencies. Tables, graphs, diagrams, and references are supplied. A literature review is appended. (Author summary modified).