Experimental Evaluation of Seismic Performance of Squat RC Structural Walls with Limited Ductility Reinforcing Details

This article describes an experimental study carried out on of reinforced concrete (RC) walls of less confining reinforcement than that recommended by ACI 318. A total of eight RC walls with boundary elements comprising of five walls with aspect ratio of 1.125 and three walls with aspect ratio of 1.625 were tested by subjecting them to low levels of axial compression loading and simulated seismic loading, to examine the structural performance of the walls with limited transverse reinforcement. Conclusions are reached concerning the failure mode, drift capacity, strength capacity, components of top deformation, and energy dissipation characteristics of walls on the seismic behavior with limited transverse reinforcement. The influences of axial loading, transverse reinforcement in the wall boundary elements, and the presence of construction joints at the wall base on the seismic behavior of walls are also studied in this paper. Lastly, reasonable strut-and-tie models are developed to help in understanding the force transfer mechanism in the walls tested.     

Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range,northwestern United States

Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and ³He/⁴He ratios as large as 8.6 R_A in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal‐monitoring effort encompassing 25 sites and 10 of the highest‐risk volcanoes in the Cascade volcanic arc, from Mount Baker near the Canadian border to Lassen Peak in northern California. A concerted effort was made to develop hourly, multiyear records of temperature and/or hydrothermal solute flux, suitable for retrospective comparison with other continuous geophysical monitoring data. Targets included summit fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high ³He/⁴He ratios and/or anomalous fluxes of magmatic CO₂ or heat. As of 2009–2012, summit fumarole temperatures in the Cascade Range were generally near or below the local pure water boiling point; the maximum observed superheat was <2.5°C at Mount Baker. Variability in ground temperature records from the summit fumarole sites is temperature‐dependent, with the hottest sites tending to show less variability. Seasonal variability in the hydrothermal solute flux from magmatically influenced springs varied from essentially undetectable to a factor of 5–10. This range of observed behavior owes mainly to the local climate regime, with strongly snowmelt‐influenced springs and streams exhibiting more variability. As of the end of the 2012 field season, there had been 87 occurrences of local seismic energy densities approximately ≥ 0.001 J/m³ during periods of hourly record. Hydrothermal responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multidecadal trends indicates that whereas the hydrothermal system at Mount St. Helens is still fast‐evolving in response to the 1980–present eruptive cycle, there is no clear evidence of ongoing long‐term trends in hydrothermal activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range hydrothermal‐monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.     

Degradation of Archaeological Wood Under Freezing and Thawing Conditions—Effects of Permafrost and Climate Change

The degradation of archaeological wood at freezing and thawing temperatures is studied at the site of Qajaa in West Greenland through a combination of environmental monitoring, measurement of oxygen consumption and microscopy of wood samples. Permanently frozen wood is still very well preserved after 2–4000 years, while wood samples that thaw every summer show attack by soft rot and an average density loss of 0.1 g cm^–3 (corresponding to 25% of the dry mass) over the past 27 years. Future increases in temperature may increase the decay rate significantly (Q₁₀ = 4.2 at 0–10°C) but the effects on site depend on local hydrology.     

Deformation of Ancient Buildings inferred by Terrestrial Laser Scanning methodology: the Cantalovo church case study (Northern Italy)*

The study of the health of a building connects humanistic and scientific research, and a complete characterization can be achieved by integrating all the available historical documentation, architectural and metrological studies, as well as laboratory and in situ analyses of the materials. A contactless, non‐invasive surveying technique such as terrestrial laser scanning (TLS) allows the acquisition of dense and accurate geometric and radiometric (electromagnetic measurements such as signal intensity) information about the observed surface of the building, which can be easily integrated with data provided by high‐resolution digital imaging. The early Christian Cantalovo church was surveyed for the first time in April 2011, by means of the ILRIS‐3D ER very long range scanner. The second and last survey was performed in June 2012, after the main shocks of the Emilia earthquake seismic sequence. A very long range instrument is suitable for fast, simple and independent measurements, due to its technical characteristics and, for this reason, is easily usable for accurate surveying in emergency conditions. The main results are obtained by applying a data analysis strategy based on the creation of TLS‐based morphological maps computed as point‐to‐primitive differences, which allow the creation of a deformation map and its evolution in time.     

无线传感网络技术在文化遗产保护领域的应用

作为物联网技术的核心技术之一,无线传感网络技术是近几年发展起来的新一代信息技术,它为文化遗产保护监测工作提供了一种网络化、实时化、智能化的新方法。对无线传感网络技术的架构和技术特点作了介绍,并对在文化遗产保护各个方面的应用案例做了简述。     

Geophysical Methods for Wreck‐Site Monitoring: the Rapid Archaeological Site Surveying and Evaluation (RASSE) programme

Rapid advances in geophysical techniques over the past decade have provided the maritime archaeological community with significant opportunities for re‐defining the procedures for wreck‐site mapping, evaluation and monitoring. The techniques which offer most potential for high‐resolution survey are acoustic‐based and include sidescan sonar, swath‐bathymetry sonar and multibeam sonar. These techniques were tested on an artificial test‐site in Plymouth Sound and over the wreck of the Stirling Castle. Results demonstrate that the techniques can provide the maritime archaeologist with the opportunity to rapidly and cost‐effectively map and monitor small, centimetric changes on sites, with the potential for long‐term monitoring and management. © 2009 The Authors     

Erosion Hazards and Efficient Preservation Measures in Prehistoric Cultural Layers in the Littoral of Lake Constance (Germany,Switzerland)

Many Neolithic and Bronze Age cultural layers and pile fields embedded in sediments at the shorelines of pre-alpine lakes in France, Switzerland, Germany, Austria, and Italy (in part UNESCO World Heritage Sites), are threatened by littoral erosion which is partly caused by human agency. Based on measurements of the wave field at four prehistoric sites on Lake Constance (Germany, Switzerland) we discuss the role of passenger ship navigation. We also review the stability and ecological compatibility of archaeological preservation control fills on the littoral platform of Lake Constance, and we make some recommendations for future preservation measures.     

Re-evaluating the Monitoring of the Shardlow Log Boat

Following the discovery of a Bronze Age log boat in Shardlow Quarry, Derbyshire in 2003, a scheme was devised to preserve this boat in situ. This included a monitoring programme to ensure that reducing conditions were maintained. This solution was agreed by the mineral planning authority Derbyshire County Council, with input and advice from English Heritage.

Monitoring lasted ten years, during which time gravel deposits surrounding the boat were extracted. The boat was protected from dewatering during this time by a clay cut-off, installed around the area containing the boat before extraction begun. After extraction the adjacent areas were backfilled with on-site soils and inert waste.

Data indicate that a reducing environment has been largely sustained during this period. Following careful and considered discussion, the monitoring programme ceased as there was unlikely to be further impacts to site hydrology, making additional data collection redundant.     

The Measurement by Airborne Synthetic Aperture Radar (SAR) of Disturbance Within the Nasca World Heritage Site

In this paper we report on our use of Synthetic Aperture Radar (SAR) as a means of monitoring the Lines and Geoglyphs of Nasca and Pampas de Jumana World Heritage Site in Peru, where the colossal ground drawings, popularly known as the Nasca Lines, are found. Our research to date indicates that the environment in which the Nasca geoglyphs are found, and the nature of the geoglyphs themselves, are suited perfectly for investigation by SAR. SAR also provides a new and valuable tool for understanding the human activities and natural processes that have damaged the geoglyphs and which, unchecked, will continue to do so in the future. Further, SAR can be used to categorize geoglyphs according to structural differences and similarities in ways that have heretofore not been possible, thereby serving as a basis for a geoglyph catalogue.     

Research and Monitoring on Conservation State and Preservation Conditions in Unsaturated Archaeological Deposits of a Medieval Farm Mound in Troms and a Late Stone Age Midden in Finnmark,Northern Norway

This paper presents archaeological observations and results of palaeoecological and geo-chemical analyses of archaeological deposits from two rural sites in northernmost Norway. These are combined with climate data and the first period of continuous monitoring of soil temperature, moisture, and redox potential in sections. This data constitutes the basic research material for evaluations of conservation state and preservation conditions. The data has been collected in collaboration with the partners of a cross-disciplinary project: ‘Archaeological Deposits in a Changing Climate. In situ Preservation of Farm Mounds in Northern Norway’ funded by the Norwegian Council for Research (http://www.niku.no/en/archaeology/environmental_monitoring/archaeological_deposits_in_a_changing_climate_in_situ_preservation_of_farm_mounds/). This is an important Norwegian research initiative on monitoring of rural archaeological deposits, and the results have consequences for heritage management of a large number of sites from all periods. Palaeoecological analyses and redox measurements have revealed ongoing decay that might not otherwise have been detected. Decay studies indicate that both site types may be at risk with the predicted climate change. Some mitigating acts are suggested.