Development and validation of European guidelines for seismic qualification of post-installed anchors.

This paper presents the technical background for the seismic qualification procedures for post-installed anchors in the European Technical Approval Guideline (ETAG 001) seismic annex issued in 2013. We discuss requirements for a comprehensive guideline and reference supporting documentation. Numerical studies to generate new simulated seismic protocols for anchors are summarized with focus on their application to Europe. To reduce the time and cost of anchor product qualification testing while fulfilling the requirement of European building codes to assess two performance categories, we combine the results of our numerical studies to generate novel testing protocols that allow for the assessment of anchor behavior at multiple levels in a unified protocol. Validation tests demonstrate that the unified protocol results in anchor performance comparable with that achieved in multiple, single-performance-level tests.

Behavior of Steel-Sheathed Shear Walls Subjected to Seismic and Fire Loads.

A series of tests was conducted on six 2.7 m × 3.7 m shear wall specimens consisting of cold-formed steel framing sheathed on one side with sheet steel adhered to gypsum board and on the opposite side with plain gypsum board. The specimens were subjected to various sequences of simulated seismic shear deformation and fire exposure to study the influence of multi-hazard interactions on the lateral load resistance of the walls. The test program was designed to complement a parallel effort at the University of California, San Diego to investigate a six-story building subjected to earthquakes and fires. The test results reported here indicate that the fire exposure caused a shift in the failure mode of the walls from local buckling of the sheet steel in cases without fire exposure, to global buckling of the sheet steel with an accompanying 35 % reduction in lateral load capacity after the wall had been exposed to fire. This behavior appears to be predictable, which is encouraging from the standpoint of residual lateral load capacity under these severe multi-hazard actions.

BEHAVIOR OF POST-INSTALLED ANCHORS TESTED BY STEPWISE INCREASING CYCLIC LOAD PROTOCOLS.

Cyclic loads are a characteristic feature of actions acting on structures and anchorages during earthquakes. For this reason, seismic qualification of post-installed concrete anchors according to the internationally recognized American Concrete Institute (ACI) standard ACI 355 is based on cyclic load tests. The protocols for these tests, however, have limited scientific basis. Therefore, in the present paper newly-developed test protocols with stepwise-increasing load amplitudes are utilized to more realistically evaluate anchor seismic performance. The study focuses on the load-displacement behavior of common anchor types installed in cracked concrete and subjected to both cyclic tension and cyclic shear actions. The results confirmed robust behavior for anchors loaded in cyclic tension even in the presence of crack widths in the anchorage material larger than currently required by ACI 355. In addition, the critical influence of low cycle fatigue on the performance of anchors loaded in cyclic shear is demonstrated.

Shake Table Testing of an Elevator System in a Full-Scale Five-Story Building.

This paper investigates the seismic performance of a functional traction elevator as part of a full-scale five-story building shake table test program. The test building was subjected to a suite of earthquake input motions of increasing intensity, first while the building was isolated at its base, and subsequently while it was fixed to the shake table platen. In addition, low-amplitude white noise base excitation tests were conducted while the elevator system was placed in three different configurations, namely, by varying the vertical location of its cabin and counterweight, to study the acceleration amplifications of the elevator components due to dynamic excitations. During the earthquake tests, detailed observation of the physical damage and operability of the elevator as well as its measured response are reported. Although the cabin and counterweight sustained large accelerations due to impact during these tests, the use of well-restrained guide shoes demonstrated its effectiveness in preventing the cabin and counterweight from derailment during high-intensity earthquake shaking. However, differential displacements induced by the building imposed undesirable distortion of the elevator components and their surrounding support structure, which caused damage and inoperability of the elevator doors. It is recommended that these aspects be explicitly considered in elevator seismic design.