Effects of Base and Lift Joints on the Dynamic Response of Concrete Gravity Dams to Pulse-Like Excitations

Near-fault earthquakes with forward-directivity effects produce pulse-like excitations. This article studies the dynamic response of monolithic and cracked sections of gravity dam under symmetric and anti-symmetric pulse-like excitations. The pulses are generated by the modified Gabor Wavelet transform. Two main characteristics of the pulses are pulse period and amplitude. The prescribed cracks are located along the base and two distinct lift joints through the dam body. The dam is modeled along with its reservoir using finite element method. The effects of base and lift joints, pulses shape, period, and amplitude, and reservoir height on the dam dynamic response are studied.     

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.     

Ground penetrating radar survey of a prehistoric site in southern Italy

In this paper, we present and discuss the results of a ground penetrating radar (GPR) study carried out in an area of southern Italy where a karst cave with prehistoric remains was found. The aim of the study involved the imaging of the subsurface stratigraphy, both inside and outside the cave, in order to assist archaeologists in an excavation programme.The survey grid comprised 18 intersecting GPR profiles. Problems associated with the use of the GPR within a cave environment are highlighted and the data processing sequence designed to extract useful geo-archaeological signatures is described. Interpretation of the radar sections was controlled by the excavation of two trenches (inside and outside the cave), allowing detailed outlining the complex stratigraphy and the reconstruction of Palaeolithic and Neolithic subsurface horizons.     

Contribution of the resistivity method to characterize mud walls in a very dry region and comparison with GPR

Mud walls are frequent in many archaeological sites, including sites located in semi-desert regions. In cases with buried walls, the geophysical methods can be useful tools for their investigation, since they provide maps of the subsoil in a non-invasive way and in relatively short times. This article deals with the characterization of mud walls in very dry soils through the resistivity method, discussing a methodology to satisfactorily apply the method in this kind of adverse environment and how to interpret the results. The case of the Palo Blanco archaeological site, a pre-Incaic village located in the NW region of Argentina, is analyzed.     

Ground truthing of remotely identified fortifications on the Central Coast of Perú

Remote imagery, including freely available satellite images viewed in Google Earth^® and historic aerial photographs, was used to identify anomalies in a 25,000 km² macroregion encompassing 13 river valleys along the Peruvian coast. These anomalies, located atop hills and mountains, were hypothesized prehispanic fortifications. A sample of remotely identified anomalies was ground truthed in the Huaura and Fortaleza Valleys on the Central Coast of Perú. 140 positive anomalies were documented and assessed using a simple defensibility index. Our results significantly increase the number of fortifications identified in both valleys. We demonstrate the efficacy of this method for locating fortifications in a very large region to facilitate the systematic documentation of these durable indicators of warfare.     

Problems of Analysis by FTIR of Calcium Sulphate–Based Preparatory Layers: The Case of a Group of 16th‐Century Portuguese Paintings

This paper provides a contribution to FTIR analysis of calcium sulphate‐based grounds of paintings when a mixture of compounds with different degrees of hydration is present. The study is based on the analysis with that technique, electron microscopy coupled with energy‐dispersive X‐ray spectrometry and X‐ray diffraction of both the grounds of 16th‐century Portuguese paintings and reference samples prepared with anhydrite and calcium sulphate dihydrate bound in an animal glue solution. It is shown that the interpretation of the degree of hydration of calcium sulphate ground samples using FTIR cannot be based solely on the study of the hydroxyl bands, as is usual in routine work, but that small deviations of the S–O vibration bands are an important indicator of the presence of anhydrite in the grounds.     

Pitted stone cobbles in the Mesolithic site of Font del Ros (Southeastern Pre-Pyrenees,Spain): some experimental remarks around a controversial tool type

The presence of cobbles with activity-related marks in the Mesolithic site of Font del Ros (Berga, Spain), and in particular one group of artefacts – pitted stones – raises problematic issues associated with the characterization of percussion activities. Although these artefacts have generated an extensive bibliography on ethological, ethnographic, ethnoarchaeological and archaeological levels, various questions persist in relation to their possible contextual function. In this paper we present the results of an experimental programme in which three types of activities that could create pitted stones are reproduced: bipolar knapping of vein quartz, hazelnut cracking, and hazelnut grinding. The aim of this experimental programme is to describe marks and use-wear traces related to such activities.