Tunnel Vaults under Seismic Excitation

This chapter discusses factors that affect the seismic response of tunnels vaults, as the seismic ground motions, the geological condition and rock mechanics properties, and the relevance of numerical analysis, fundamental in the modeling of complex structures and processes, and in regional-scale analysis. As an example, this chapter focuses on the Laboratories of National Institute of Nuclear Physics (INFN) located in a Tunnel within the Gran Sasso mountain (Abruzzo, Italy). In addition to the L’Aquila (2009) earthquake, the chapter refers to observations reported in the literature related to the İzmit earthquake, Turkey (1999); the Chi-Chi earthquake, Taiwan (1999); and the Kobe earthquake (2004); and, as historical event, the Kern County earthquake (1952)

Poinçonnement des planchers-dalles avec colonnes superposées fortement sollicitées

Flat slabs are commonly used in buildings due to their easiness of construction and economy. In order to keep these advantages, columns are usually not continuous through the slabs in multi-storey buildings. In these cases, the slabs are subjected to large compressive stresses at the support area of the columns, which can exceed the uniaxial compressive strength of the concrete of the slab. This critical zone is in addition subjected to large shear forces and bending moments due to the loads applied on the slab. This leads to a series of potential failure modes: crushing of the concrete of the slab between columns, flexural failures or punching shear failures. Most research has previously focused on the influence of bending of the slab on the column strength. However, no works have provided in-depth investigation of the strength of the slab when large column loads are applied. In this research, an extensive experimental program has shown that the stresses applied at the support area of the columns can be significantly larger than the uniaxial compressive strength of concrete. The test results have clearly shown that no special confinement or load transfer devices are required between columns for most cases (moderate column loads). In addition, two phenomena have been observed. The first one is a reduction on the flexural strength as column loads are applied. The second corresponds to a significant increase on the punching shear strength and deformation capacity with column loading. Existing theoretical approaches for flat slab behaviour and strength are shown not to be directly applicable for slabs subjected to large column loading. In this research, the principles of two general theories (the theory of plasticity and the critical shear crack theory) are thus used to investigate such cases. The theory of plasticity allows calculating a plastic failure envelope accounting for bending and column loading, whereas the critical shear crack theory, which in this work as been further investigated theoretically, is used to derive a failure criterion accounting for punching shear failure in presence of column loading. The results for both theories are finally presented in terms of a single interaction diagram between column loading and slab loading (bending and shear of the slab). The theoretical approaches require however the help of rather refined numerical tools for estimating the strength of a flat slab. In order to use the theoretical approaches for design, a simplified approach has been developed, allowing to calculate the strength as well as the deformation capacity of flat slabs. These tools were implemented in a design method for slab-column joints in multi-storey building. This design approach allows to derive simplified interaction diagrams that can be compared with the loading history of the structural element analysed

Visual learning induces changes in resting-state fMRI multivariate pattern of information

When measured with functional magnetic resonance imaging (fMRI) in the resting state (R-fMRI), spontaneous activity is correlated between brain regions that are anatomically and functionally related. Learning and/or task performance can induce modulation of the resting synchronization between brain regions. Moreover, at the neuronal level spontaneous brain activity can replay patterns evoked by a previously presented stimulus. Here we test whether visual learning/task performance can induce a change in the patterns of coded information in R-fMRI signals consistent with a role of spontaneous activity in representing task-relevant information. Human subjects underwent R-fMRI before and after perceptual learning on a novel visual shape orientation discrimination task. Task-evoked fMRI patterns to trained versus novel stimuli were recorded after learning was completed, and before the second R-fMRI session. Using multivariate pattern analysis on task-evoked signals, we found patterns in several cortical regions, as follows: visual cortex, V3/V3A/V7; within the default mode network, precuneus, and inferior parietal lobule; and, within the dorsal attention network, intraparietal sulcus, which discriminated between trained and novel visual stimuli. The accuracy of classification was strongly correlated with behavioral performance. Next, we measured multivariate patterns in R-fMRI signals before and after learning. The frequency and similarity of resting states representing the task/visual stimuli states increased post-learning in the same cortical regions recruited by the task. These findings support a representational role of spontaneous brain activity

Behaviour and design of slab-column joints

This paper presents an investigation on the behaviour and strength of slab-column joints in multystorey buildings. Such joints may develop different potential failure modes such as crushing of the concrete of the slab (due to column loading), bending or punching shear failures (due to slab loading). The paper presents the results of a test series on 9 full-scale slabs (250 mm thick) loaded to simulate simultaneously column and slab loading. The ratio between the loads was varied from moderate to fairly large column loading. The experimental results confirm a strong interaction between column and slab loads with unexpected increases on the punching shear strength as column loads are larger than the uniaxial compressive strength of the slab. The observed behaviours can be explained on the basis of the theory of plasticity and by using the Critical Shear Crack Theory, leading to a physically-grounded design method for these regions

Gamma-spectrometric measurement of radioactivity in agricultural soils of the Lombardia region, northern Italy

Abstract This work is part of a wider monitoring project of the agricultural soils in Lombardia, which aims to build a database of topsoil properties and the potentially toxic elements, organic pollutants and gamma emitting radionuclides that the topsoils contain. A total of 156 agricultural soils were sampled according to the LUCAS (Land Use/Cover Area frame statistical Survey) standard procedure. The aim was to provide a baseline to document the conditions present at the time of sampling. The results of the project concerning soil radioactivity are presented here. The aim was to assess the content of 238U, 232Th, 137Cs and 40K by measuring soil samples by gamma spectrometry. 238U, 232Th and 40K activities range 24–231, 20–70, and 242–1434 Bq kg−1 respectively. The geographic distribution of 238U reflects the geophysical framework of the Lombardia region: the soils with high content of uranium are distributed for the most part in the South Alpine belt, where the presence of magmatic rocks is widespread. These soils show an higher activity of 238U than of 232Th. The 238U activities become lower than 232Th when soils are located in the plain, originating from basic sedimentary rocks. 137Cs activity ranges 0.4–86.8 kBq m−2. The lowest activity of 137Cs is in the plain, whereas the highest is in the North on soils kept as lawn or pasture. The 137Cs activity of some samples suggests the presence of accumulation processes that lead to 137Cs enriched soils. This is the first survey of gamma emitting radionuclides in Lombardia that is based on the LUCAS standard sampling. The results from this monitoring campaign are important for the human radiation exposure and provide the zero point, which will be useful for assessing future effects due to external factors such as human activities

Results and lessons learned of a subjective field operational test on the lane departure warning function

The paper presents the preliminary results and the lessons learned from the Italian Field Operational Test on the Lane Departure Warning (LDW) function that is being carried out within the European project euroFOT. The FOT has deployed a large scale subjective test involving a sample of 570 drivers and using a wide and differentiated set of self-reported questionnaires about system usage and impact. The purpose of the FOT is to investigate the subjective aspects about LDW system users' acceptance and the perceived impact of the LDW system on safety, driving behaviour and transport-related aspects. Results are expected to accurately depict the actual impact of this function based on subjective data

Crushing and Flexural Strength of Slab-Column Joints

In multi-storey buildings, columns are usually not continuous through the slabs to enhance ease of construction. Consequently, in slab–column joints, slabs have to carry column loads in addition to the shear and bending moments due to loads applied to the slab. In most cases, when high strength concrete is used for the columns and normal strength concrete for the slabs, compression stresses at the support areas of the inner columns exceed the uniaxial compressive strength of the concrete of the slab. Due to this reason, most current details for such regions reinforce the concrete of the slab between columns to ensure load transfer. Typically, this is achieved by linking top and bottom columns with reinforcement. Sometimes, it is also needed to incorporate special load transfer devices. This latter solution is however relatively complicated and expensive. In this paper, the crushing and flexural strength of slab–column joints is investigated accounting for an increase of the compressive strength of the failure region (concrete between columns) due to confinement stresses provided by the flexural reinforcement of the slab. The results of an experimental programme on 6 full-scale slabs (250 mm thick) are presented showing that flexural reinforcement of a slab significantly increases the crushing strength of slab–column joints. This allows ensuring load transfer without incorporating special devices or even without linking top and bottom column reinforcement for a wide range of cases leading potentially to more economic designs. An analytical approach, grounded on the theory of plasticity, is also presented allowing one to determine a failure criterion for such regions. This approach, which can also be used for design purposes, leads to an excellent correlation with test results