End‐Member Mixing Analysis (EMMA) Applied to Sediment Grain Size Distributions to Characterize Formational Processes of the Main Excavation Block,Unit 2, of the Rimrock Draw Rockshelter (35HA3855), Harney Basin,Eastern Oregon (USA)

End‐member mixing analysis (EMMA) was conducted on the grain size distributions (GSD) of 13 sediment samples collected from the main excavation block, Unit 2, of the Rimrock Draw Rockshelter, a deeply stratified, multi‐component Palaeoindian rockshelter in the Harney Basin of eastern Oregon, USA. EMMA confirmed the three stratigraphic units (SU) observed in the field and identified three sedimentary end‐members (EM) that account for 95.52% of Unit 2 site formation. EM 1 comprises 70.72% of the total measured grain‐size variation and represents fluvial deposition, correlating with the bottom stratigraphic unit, SU 3. EM 2 comprises an additional 17.74% of the total measured grain‐size variation and represents fluvially reworked aeolian deposition, correlating with the upper stratigraphic unit, SU 1. EM 3 comprises the remaining 7.06% of the total measured grain‐size variation and represents possibly a two‐component aeolian deposition of suspension and short‐term saltation, correlating with the middle unit, SU 2. The results presented demonstrate the ability of EMMA as a technique to (1) unbiasedly distinguish between the SUs identified in the field using only the measured grain size distributions, (2) provide genetically meaningful and quantitative grain‐size end‐members to identify multiple major depositional processes of site formation, and (3) provide a geologically meaningful interpretation of site formation that is capable of facilitating the formulation of more focused hypotheses regarding human and environment interactions at the site.     

An Examination of Terminal Archaic Bone and Antler Implements from the Firehouse Site,Dearborn County,Indiana

The Firehouse site (12D563) is a Terminal Archaic Riverton culture site located on a bluff overlooking the confluence of the Ohio and Great Miami Rivers in Dearborn County, Indiana. Excavations at the site in 2003 and 2004 yielded a highly diverse assemblage of around 300 bone and antler implements. Such large assemblages of organic tools are rare outside of wet sites, rockshelters, and shell middens and provide a unique opportunity for the study of tool forms not typically recovered in the Midwest. A typological analysis of the Firehouse assemblage indicates some similarities between these tools and Riverton culture bone and antler implements from the type sites in Illinois. Additionally, a microscopic analysis of manufacturing microtraces indicates that most tools were made using a lithic shaving (rather than an abrasion) technique.     

Ochre fingerprints: Distinguishing among Malawian mineral pigment sources with Homogenized Ochre Chip LA–ICPMS

In this study, we compared the effectiveness of instrumental neutron activation analysis (INAA) of bulk ochre to laser ablation‐inductively coupled plasma mass spectrometry of homogenized ochre chips (HOC LA–ICPMS) at distinguishing among three ochre sources in northern Malawi. Both techniques upheld the Provenance Postulate; however, HOC LA–ICPMS required less sample material than INAA and facilitated fast, inexpensive replicate observations that allowed for more robust statistical analysis. Our results indicated that HOC LA–ICPMS is a maturing technique that will be a valuable option for analysing artefacts that require minimally destructive sampling but are too large to fit into the laser cell for direct ablation. With regard to the statistical procedures used, stepwise canonical discriminant analysis was demonstrated to be a highly effective method for distinguishing among ochre sources, even in the presence of significant intra‐source and intra‐sample heterogeneity. Continued development of the HOC sample preparation technique will expand the range of archaeological ochre artefacts that can be included in provenance studies and prevent bias towards artefacts of convenient‐to‐analyse dimensions.     

Design Principles for Minimum Torsional Response of Wall-Frame Concrete Structures

A seismic design procedure is described incorporating the well-accepted property that the stiffness of reinforced concrete elements is strength dependent and the requirement that the method of assigning strength to elements should be aiming at minimum torsional phenomena. Such a response allows a direct comparison with the findings of a static nonlinear analysis, which may provide the limits of story drifts and the induced plastic rotations in potential plastic hinges. The requirement of a practically translational response implies that the element strength assignment should be based on planar considerations and the initially elastic response should be of minimum torsion.     

Investigation of the Optimum Height of Railway Embankments during Earthquake Based on Their Stability in Liquefaction

One of the most reported problems in the railway embankments is loss of their overall stability and major settlements due to liquefaction. Although several studies have been made on the stabilization of embankments, the effects of the influencing parameters on the stability of embankments during liquefaction have not been sufficiently investigated. The series of two dimensional plane strain finite element (FE) models were developed using multi yield surface plasticity model namely Prevost. The results were represented and discussed in terms of foundation excess pore pressure, embankment settlements and their failure modes. By analyzing the results, the optimum height of embankment which minimizes the settlement and failure cracks was derived.     

Critical Assessment of Intensity Measures for Seismic Response of Italian RC Bridge Portfolios

The seismic assessment of a road network depends largely on the characterization of the fragility of its bridge components. The accuracy of bridge seismic demand estimates and the use of proper intensity measures (IM) will significantly influence such task. The available literature has mainly focused on buildings or a limited number of bridge configurations and IMs, which may not be representative for bridge portfolio assessment studies. In this paper, the correlation quality between a larger pool of traditional and innovative IMs and the nonlinear dynamic response of typical Italian RC bridges is investigated to identify the best-performing IMs.     

Experimental Study of Large Area Suspended Ceilings

Damage of nonstructural components during past seismic events was shown to be not only a critical threat to life safety in extreme cases but also led to substantial reduction of functionality of buildings and other facilities. Because of the complex construction of nonstructural and architectural components, current standards provide only limited guidance for the seismic design. Suspended ceiling systems are among the less understood important nonstructural/architectural components in buildings for which design standards provide limited guidance. To understand the dynamic behavior of suspended ceiling systems, a series of full scale shake table tests of 20 ft × 53 ft and 20 ft × 20 ft ceiling systems were conducted at the Structural Engineering and Earthquake Simulation laboratory (SEESL) at University at Buffalo (UB). For the full scale dynamic testing, a new test frame providing a continuous suspended ceiling area of 1,060 ft² was constructed on the tandem shake tables and was equipped with an open-loop shake table compensation procedure. The combined designs of the physical frame and of the shake table motion controllers allowed simulating the required floor/roof motion according to ICC-ES AC156 standard at the roof of the test structure. Various test configurations were selected in order to determine the influence of different system conditions and the effects or efficiency of various protective systems required by the current standard ASTM E580 for seismic design. Based on the test data and the failure mechanisms observed, damage states are defined, and fragility curves are developed. The results of the fragility analysis show that a ceiling system becomes more vulnerable as (a) it is subjected to multi-directional input motions, (b) heavier tiles are installed, (c) the size of a ceiling area increases, and (d) lateral restraints are not installed. In addition, simplified numerical models that can capture the special behavior of ceiling systems are developed and presented in a companion paper. This paper presents the experimental study of large area suspended ceiling systems involving test setup and configurations, test motions generated by a unique control system, and basic lessons gained from the experiments.     

Mixed Force and Displacement Control for Testing Base-Isolated Bearings in Real-Time Hybrid Simulation

This paper presents a robust mixed force and displacement control strategy for testing of base isolation bearings in real-time hybrid simulation. The mixed-mode control is a critical experimental technique to impose accurate loading conditions on the base isolation bearings. The proposed mixed-mode control strategy consists of loop-shaping and proportional-integral-differential controllers. Following experimental validation, the mixed-mode control was demonstrated through a series of real-time hybrid simulation. The experimental results showed that the developed mixed-mode control enables accurate control of dynamic vertical force on the base isolation bearings during real-time hybrid simulation.     

Experimental Study on Seismically Resilient Two-Span Bridge Models Designed for Disassembly

Shake-table studies were conducted on a ¼-scale, 2-span bridge model incorporating a newly-developed concept of replaceable plastic hinges and columns that can be easily assembled and disassembled. The plastic hinges incorporate novel materials that mitigate column damage and permanent drift, allowing the bridge to undergo intense seismic shaking and remain operational when most conventional bridges would warrant demolition. Designed to be disassembled, the column components have the potential to be reused, which is intended to help mitigate the environmental impact from material extraction and manufacture. The concept feasibility was demonstrated by assembling, testing, and disassembling the same bridge model twice.     

Cost-Benefit Analysis of Alternative Retrofit Strategies for RC Frame Buildings

Monetary losses induced by earthquakes in Reinforced Concrete (RC) buildings are mainly due to damage to non-structural elements (infills, partitions, finishes, etc.). In this study, alternative retrofit strategies for reducing monetary losses in RC frame buildings are examined. They include local strengthening of infills (and partitions) and seismic isolation. The Expected Annual Loss (EAL) of a number of RC frame buildings, pre- and post-rehabilitation, is evaluated, following the time-based assessment approach proposed in the FEMA P-58 guidelines. The breakeven time of each retrofit intervention is then computed, considering the initial cost of the intervention and the expected benefit in terms of EAL reduction.