This technical audit report contains the results of physical tests performed on the Boykin Anchor Company, Inc. (BSI) Concrete Expansion Anchors. Physical testing included both dynamic and static procedures to determine conformance to BSI's published specifications and Bellcore's environmental compatibility criteria for earthquake resistance. The report is based on the requirements and objectives contained in the Bellcore Technical Reference, TR-NWT- 000063, Network EquipmentBuilding System (NEBS), Generic Equipment Requirements, Issue 5, September 1993, (TR-63).
Three sizes of BSI Anchors were tested: M10, M12, and M16 -1045. A series of both Dynamic and Static tests were performed.
1.1 Dynamic Test Method
Earthquake tests were performed in accordance with TR-63 and ASTM 488-90. Both of these documents specify that earthquake tests are to be performed in a manner that represents 'as installed' conditions. An earthquake test was developed for each anchor size to represent the floor fastening of a telecommunications equipment rack. Bellcore developed the appropriate worst case weight loading of the rack to stress the anchors during a simulated earthquake. These tests replicate typical field conditions of heavily loaded frames, with narrow bases, that are exposed to Zone 4 earthquake conditions.
Each test assembly, consisting of the loaded rack, anchors, and concrete base, was mounted to a shaker table. The shaker table motion was controlled to simulate Zone 4 earthquakes in accordance with TR-63 test procedures. The acceleration input to the test specimen was carefully controlled. Anchor performance was determined by measuring torque retention. During some tests, selected anchors were instrumented with load cells to directly record the anchor load during the shaking.
1.2 Static Test Methods
The three anchor sizes were installed in sample concrete blocks, having a 3,400 psi compressive strength. A minimum of six of each size anchor was used for each test to obtain a statistically sign)ficant sample of data.
1.2.1 Tensile Tests
Tensile testing of the anchors was performed in accordance with ASTM 488-90 Standard Test Methods for Strength of Anchors in Concrete and Masonry Elements. Tensile anchor failure is often identified by a diagonal tension failure of the concrete resulting in a shear cone pull-out. Stands were designed to span across the anchor and avoid direct interference with the shear cone. Stands capable of sustained loads up to 25,000 pounds were used for tensile tests.
The test method was as follows:
An anchor was first set in the
concrete through a mechanical coupler. The stand was set
in place above the anchor. A vertical pull-out force was
exerted on the anchor by a hydraulic cylinder and
measured via a load cell. (See Figure 1). Simultaneously,
anchor lift was recorded
Descriptions of the various mechanical expansion anchor failure modes are as follows:
1. Anchor Bolt Failure - Ductile failure of the anchor's bolt in tension.
2. Concrete Cone Failure - A diagonal tension failure of the concrete resulting in a shear cone pullout.
3. Anchor Slip - Anchor withdrawal from the anchor's hole.
Shear testing was performed in accordance with ASTM 488-90. The shear test fixture was designed to avoid direct interference with the stress field of the anchor. A fixture capable of sustained loads up to 25,000 pounds was used for all shear tests.
The test method was as follows:
An anchor was first set through a pulling shoe, into the concrete. To load the anchors in shear, a fixture and hydraulic jack were mounted off the side of the concrete slab. The applied load was measured via a load cell placed on the end of the jack. A threaded rod connected the hydraulic jack to the pulling shoe. (See Figure 2). During testing the anchor type, style, concrete strength, and other data were also recorded. From this data, averages of samples were calculated as well as minimum and maximum values. The results are recorded in Appendix B.
Description of the various mechanical expansion anchor failure modes are as follows:
1. Anchor Bolt Failure - Ductile failure of the anchor's bolt in shear.
2. Concrete Failure - A diagonal tension failure resulting in a slab edge failure.