Search results for "concrete"
showing 10 items of 262 documents
HISTORICAL SCIENTIFIC AND EXPERIMENTAL RESEARCHES AIMED AT FINDING NEW TECHNIQUES AND INSTRUMENTS TO RECOVER
2005
The “building recovery” has been the key point of various talks that, since the ‘60s, have regarded planning and urban landscaping. The reinforced concrete-ruled XXth century has generated buildings that have resulted technologically flawed, if not altogether unattractive. These flaws can be justified by premature use of certain techniques (not will-known the necessity of historical research), but this can not justify the modern degraded townships, the loss of local urban characteristics and the environmental unbalancing. Where sites are of XXth century cultural heritage? Which are the methodologies for documenting and managing? This research is aimed at analysing new techniques and materia…
A Viscoelastic Model for the Long-Term Deflection of Segmental Prestressed Box Girders
2017
Most of segmental prestressed concrete box girders exhibit excessive multidecade deflections unforeseeable by past and current design codes. To investigate such a behavior, mainly caused by creep and shrinkage phenomena, an effective finite element (FE) formulation is presented in this article. This formulation is developed by invoking the stationarity of an energetic principle for linear viscoelastic problems and relies on the Bazant creep constitutive law. A case study representative of segmental prestressed concrete box girders susceptible to creep is also analyzed in the article, that is, the Colle Isarco viaduct. Its FE model, based on the aforementioned energetic formulation, was succ…
The Effectiveness of LDOCE Definitions for Concrete and Abstract Nouns in Headword- and Picture-Identification Tasks
2021
Abstract LDOCE uses a defining vocabulary to make their definitions intelligible to the user. Critics claim this policy may result in imprecise definitions, something especially noticeable in certain concrete and abstract words that are difficult to define by a definition only. This paper examines to what extent LDOCE definitions of such words help learners identify the objects and words being defined. In our experiment on 381 learners of English as a foreign language, three groups of participants viewed different definition types: simplified definitions of LDOCE, unsimplified definitions of MWC, and definitions written in the learners’ mother tongue (UDPL/TR). The results show that the LDO…
Warum ist Pränataldiagnostik in der Diskussion? Eine Einführung
2017
Prenatal diagnosis has been a subject of intense discussion since it became technically achievable. This is because the results it provides can dramatically change the attitude of mothers towards their unborn children, and can lead to considerable social pressure to abort the child. These undesirable effects might come as a surprise, given that prenatal testing was primarily intended to allow better care for infants waiting to be born. The possible risks of invasive procedures and the only statistical evidence of results are the factors most responsible for the ambivalent attitudes that surround prenatal diagnosis. Another significant factor is the discrepancy between the general availabili…
SHEAR RESISTANCE OF R/C BEAMS PROVIDED WITH DIFFERENTLY-INCLINED TRANSVERSE REINFORCEMENT
2012
The model for the evaluation of shear resistance of reinforced concrete member provided with transverse web reinforcement, derived by Nielsen (1999) on the basis of the variable inclination stress field approach, is generalized here to predict the shear strength of r.c. beams equipped with two sets of differently-inclined transversal web reinforcement and longitudinal skin reinforcement. Numerical analyses emphasize the efficiency of double inclined web transverse reinforcement in providing shear strength to beams.
Innovative Recycling of Lime Slaker Grits from Paper-Pulp Industry Reused as Aggregate in Ambient Cured Biomass Fly Ash-Based Geopolymers for Sustain…
2019
Lime slaker grits and biomass fly ash are solid wastes produced by the Kraft paper-pulp industry that are commonly disposed of in landfill. However, recent studies and European regulations discourage such disposal practices. This work investigates an alternative and innovative way to recycle and reuse these wastes in the production of green geopolymeric mortars intended for application in the construction industry. Here, biomass fly ash was used as the main source of alumino-silicate in the binder precursor (70 wt.% substitution to metakaolin), and grits (ranging from 1&ndash
Cupole in cemento armato in Sicilia occidentale nella prima metà del Novecento
2014
The paper intends to examine through three case studies the change introduced by the technology of reinforced concrete in the construction of domes. After a brief description of the geometric and architectural characteristics of reinforced concrete domes, the study focuses on three interventions, for which a considerable archival documentation was collected. Chronologically the first intervention is related to the construction of the dome of the mother-church of Bisacquino (1923-25), built on the basis of the architectural project and under the direction of the engineer Pietro Scibilia. The second concerns the reconstruction of the dome of Sant’Ignazio martire all'Olivella church in Palermo…
Assessment and strengthening of reinforced concrete bridges with half-joint deterioration
2022
Existing Niagara-type concrete cantilever bridges, which in Italy are called Gerber bridges, suffer from degradation due to reinforcement corrosion and a consequent reduced load-bearing capacity. The assessment of these structures is therefore an important part of the procedures for analyzing the state of existing bridges and any interventions required for their retrofitting. In particular, safety against failure of the half-joint must be evaluated with respect to the behavior of the entire bridge and its state of conservation, determining what the conditions are that lead to failure, in terms of loads, state of stress, and possibly cracking state. This evaluation has to be carried out cons…
Seismic tomography tests applied to a gravity dam
2016
The control of the safety assessment of a dam is largely dependent on knowledge of the mechanical parameters of the actual construction, as well as its geological substratum. The application of geophysical methods can be used in existing dams to evaluate the materials (strength properties) and to verify if they match design expectations, as well as to contribute to the safety control. In particular seismics methods can considerably contribute to the examination indicating the less consolidated material and the degradation of mechanical parameters. For the characterization of the concrete conservation three seismic tomographies and a vertical seismic profile on the dam body were performed.Th…