The stretch length of an anchor is defined as the length over which plastic deformations are expected to occur during seismic loading. Providing system ductility via the stretch length is an attractive design philosophy, particularly for structural system types where energy dissipation and ductility are not easily integrated elsewhere. This paper presents a basis for stretch length design including data from a large testing program of commonly used anchor materials. More than 90 tension tests of all-thread and headed anchors were conducted to determine strength characteristics, the relationship between anchor deformation capacity and stretch length, and serviceability limit states. Subsequently, simple analytical methods to determine the required stretch length for common connection configurations, including building column baseplate connections and nonbuilding structures, are developed. The paper concludes by providing a rational stretch length design framework as an alternative to the current ACI 318 prescriptive requirement of eight times the anchor diameter.

A landmark experimental program was conducted to advance the understanding of nonstructural system performance during earthquakes. The centerpiece of this effort involved shake table testing a full-scale five-story reinforced concrete building furnished with a broad variety of nonstructural components and systems (NCSs) including complete and operable egress, mechanical and electrical systems, facades, and architectural layouts. The building-NCS system was subjected to a suite of earthquake motions of increasing intensity, while base-isolated and then fixed at its base. In this paper, the major components of the test specimen, including the structure and its NCSs, the monitoring systems, and the seismic test protocol are described in detail. Important response and damage characteristics of the structure are also presented. A companion paper describes the damage observed for the various NCSs and correlates these observations with the structure's response.

Nonstructural components and systems (NCSs) provide little to no load bearing capacity to a building; however, they are essential to support its operability. As a result, 75–85% of the initial building financial investment is associated with these elements. The vulnerability of NCSs even during low intensity earthquakes is repeatedly exposed, resulting in large economic losses, disruption of building functionality, and concerns for life safety. This paper describes and classifies damage to NCSs observed during landmark shake table tests of a full-scale five-story reinforced concrete building furnished with a broad variety of NCSs. This system-level test program provides a unique dataset due to the completeness and complexity of the investigated NCSs. Results highlight that the interactions between disparate nonstructural systems, in particular displacement compatibility, as well as the interactions between the NCSs and the building structure often govern their seismic performance.

With the 2014 update of the U.S. Geological Survey (USGS) National Seismic Hazard Model (NSHM) as a basis, the Building Seismic Safety Council (BSSC) has updated the earthquake ground motion maps in the National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions for New Buildings and Other Structures, with partial funding from the Federal Emergency Management Agency. Anticipated adoption of the updated maps into the American Society of Civil Engineers Minimum Design Loads for Building and Other Structures and the International Building and Residential Codes is underway. Relative to the ground motions in the prior edition of each of these documents, most of the updated values are within a ±20% change. The larger changes are, in most cases, due to the USGS NSHM updates, reasons for which are given in companion publications. In some cases, the larger changes are partly due to a BSSC update of the slope of the fragility curve that is used to calculate the risk-targeted ground motions, and/or the introduction by BSSC of a quantitative definition of “active faults” used to calculate deterministic ground motions.

Based on current special moment frame design requirements, reinforced concrete beam-column joints in frame buildings are designed to resist seismic loads, yet they suffer severe damage in the form of plastic hinging in the beams when design limits are attained In this paper, the full-scale experimental reversed cyclic behavior of an alternative subsystem incorporating high-strength reinforcing in a beam-column joint is summarized. Observations from the experiment indicate that the specimen exhibits stable hysteretic behavior up to approximately 5.5% drift ratio. At design plastic rotations expected of conventional beam-column joints, the specimen exhibited no joint spalling with only minor damage and flexural cracks well extended along beam members. In addition, a design-oriented numerical model of the test subassembly is described and shown to reasonably capture the global and local behavior of the specimen.

When designed according to current special moment frame requirements, conventional RC beam-column joints in frame-braced buildings subject to design level seismic loads suffer severe damage. Construction of these conventional beam-column joints is also costly and labor intensive. In this paper, the full-scale experimental behavior of two alternative frame-braced subassemblies incorporating ductile embeds is summarized. Observations from the experiments indicate that both specimens exhibit stable hysteretic behavior with no strength degradation in excess of 7% drift ratio. At design plastic rotations expected of conventional beam-column joints, no joint spalling and only minor damage along beam members was observed. A design-oriented lumped element model is described, which reasonably captures the local behavior of the specimens.

This paper presents observations of buffer implementation and usage during the construction of a five-story, full-scale, reinforced concrete, earthquake test structure. Over 40 private industry partners performed a majority of the construction work inkind, each covering a different scope of work. Activity durations were often longer than expected, particularly because research interests often resulted in changes in scopes of work for partners, sometimes requiring design work. Due to the fluctuation between the initial baseline construction lookahead schedule developed early in the project, and the pace of actual construction, inventory often sat in the laydown area or in the workface area for lengthy periods of time. This was true even though a pull approach was used to coordinate activities. A simulation experiment was used to determine the impact on inventory levels of activity durations exceeding planned durations. Because material lead times were on the order of the planning horizon, orders for upcoming activities were often made without knowledge of delays in intermediate activities, resulting in additional inventory time on the site. The simulation experiment exhibited a similar behavior, and showed that excess inventory levels increase rapidly with the degree to which actual durations extend beyond planned durations.

A rational procedure is developed for applying equivalent nonstructural static force design requirements to generate a dynamic qualification test method for seismic validation of equipment for commercial (nonnuclear) service. The equipment qualification required response spectrum (RRS) is derived based on the National Earthquake Hazard Reduction Program’s (NEHRP) lateral force procedure in conjunction with the building design earthquake response spectrum. This approach accounts for above grade elevation equipment installations, with or without knowing the building dynamic characteristics. Provisions are included to extend the qualification methodology to families of products by employing type-testing rationalization techniques. A well-defined pass/fail acceptance criterion is established that utilizes the equipment importance factor to define post-test acceptability. This procedure is the first recognized seismic qualification test protocol for shake-table testing to address secondary system and nonstructural building component requirements as defined by the primary model building codes being employed in the United States.

Currently the most widely accepted code regulations in the United States for seismic design of structures and nonstructural components are those found in the Uniform Building Code ( UBC). The UBC seismic requirements were significantly revised in the 1997 edition. Among the issues addressed in the UBC revisions are near-source effects and ground acceleration dependent soil site amplification factors for both short- and long-period structures. Also, the design force levels in the 1997 UBC are based on strength design rather than allowable stress design, as had been used previously. Other significant changes include introduction of a redundancy/reliability factor, a more realistic consideration of story drift and deformation compatibility, and new equations for equivalent static forces for both structural and nonstructural components. This paper traces the recent history of the code development and describes the major elements of the 1997 UBC seismic provisions.

This paper describes the mechanical operation and presents parametric studies for the Energy Dissipating Restraint (EDR). The EDR is a strongly self-centering passive friction-based seismic energy dissipator with a wide range of hysteretic behaviors. In the behaviors of most interest in seismic design, the slip load is proportional to displacement. Typically the EDR would be installed in a building as part of the bracing system which resists seismically induced lateral forces.