Search results for "concrete"
showing 10 items of 262 documents
Masonry infills and RC frames interaction: Literature overview and state of the art of macromodeling approach
2015
The issue of the influence of masonry infills within RC frames structures has been widely investigated in the last decades by several researchers. The large interest addressed to this topic depends on the actual observation that when in presence of seismic events, the response of framed structures is strongly conditioned by the interaction with the infill walls, which however are considered as non-structural elements and not included in the models. The influence of masonry infills role in structural response is so much relevant to affect not only the overall strength and the stiffness but it may also radically change the possible collapse mechanisms of the overall structural complex under t…
Flexural behaviour of external R/C steel fibre reinforced beam-column joints
2011
ABSTRACT A softened strut-and-tie macro model able to reproduce the flexural behaviour of external beam-column joint is presented. The model is specific for concrete with hooked steel fibres (FRC) and it is designed to calculate the flexural response, as load-deflection curve, of a beam-column sub-assemblages. The model considers the presence of a constant vertical load acting on the column and of a monotonically increasing lateral force applied at the tip of the beam.
Evaluation of a microclimate model for predicting the thermal behavior of different ground surfaces
2013
The microclimate model ENVI-met Version 4 was evaluated with field data in terms of the thermal behavior of different types of ground surface. A field experiment was conducted in a real construction project in Guangzhou, South China, from 29 August to 2 September in 2010. The surface types of concrete, tile, asphalt and grass were investigated. The comparison between observation and prediction was performed for both sub- and above-surface variables, including soil temperature at different depths, soil heat flux at the surface, surface temperature, and air temperature and humidity at different heights. The results show that the ENVI-met model is capable of reasonably modelling the diurnal th…
Concrete columns confined with fibre reinforced cementitious mortars: Experimentation and modelling
2014
Abstract The structural behaviour of concrete columns strengthened with a system made up of fibre nets embedded in an inorganic stabilized cementitious matrix under an uniaxial load was investigated. Medium size specimens with circular and square cross-section were cast and subjected to monotonic uniaxial compression, to investigate the efficiency of a p-Phenylene BenzobisOxazole (PBO) Fibre Reinforced Cementitious Mortar (FRCM) system in increasing both strength and ductility. The experimental results show that the confinement system adopted produced a noticeable increment in strength and ductility, though the low mechanical ratios of fibre considered were not always able to ensure hardeni…
THE RESISTANCE TO FATIGUE OF DRY ASPHALT RUBBER CONCRETE FOR SUB-BALLAST LAYER
2015
The more and more frequent use of recycled materials within the road and railway infrastructures is now an irreversible trend. In this area the use of Dry Asphalt Rubber Concrete (DARC) in sub-ballast layer seems to be a suitable technique to reach high mechanical and environmental performance even if such material should be analyzed over a long time horizon. This paper presents the results of experimental research focused on the resistance to fatigue of Dry Asphalt Rubber Concrete in sub-ballast layers; the survey has been carried out using four-point bending test (4pbt) on mixture samples with different rubber contents. The results of fatigue in DARC have been compared with the performanc…
Design of RC joints equipped with hybrid trussed beams and friction dampers
2021
Abstract The challenge of this research consists in the first attempt to apply a dissipative friction connection to beam-to-column joints with semi-prefabricated Hybrid Steel-Trussed Concrete Beams (HSTCB) and RC pillars cast in-situ. Nowadays, HSTCBs are widely adopted in civil and industrial buildings and, therefore, it is required to evaluate their compliance with the capacity design criteria and their seismic energy dissipation capability. However, the design of the reinforcement of such beams usually lead to the adoption of large amount of steel within the panel zone which becomes potentially vulnerable to the effects of seismic cyclic actions and dramatically reduce the dissipation ca…
Prediction of the Fundamental Period of Infilled RC Frame Structures Using Artificial Neural Networks
2015
The fundamental period is one of the most critical parameters for the seismic design of structures. There are several literature approaches for its estimation which often conflict with each other, making their use questionable. Furthermore, the majority of these approaches do not take into account the presence of infill walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period. In the present paper, artificial neural networks (ANNs) are used to predict the fundamental period of infilled reinforced concrete (RC) structures. For the training and the validation of the ANN, a large data set i…
6th Workshop on The New Boundaries of Structural Concrete 2022 University of Salento – ACI Italy Chapter
2022
Geopolymer cement is a viable alternative to ordinary cement in order to significantly reduce the emission of carbon dioxide related to the construction of concrete structures. Being made up of waste materials, geopolymer cement also helps to limit the use of new raw materials, leading to a considerable reduction of the environmental impact of the construction industry. During the last years, the use of Geopolymer Recycled Aggregate Concrete (GRAC) in structural members has been studied in several recent experimental research in which the behavior of either the material or structural member was investigated. A review paper will be done critically to compile the present research on the use o…
LONG-TERM STRUCTURAL DEFICIENCIES IN A MAT FOUNDATION ON CLAY SOIL
2013
A 3-story building with a mat foundation consisting of a slab on a grid of grade beams performed poorly on clay soil. Cracking of the slab became rogressively worse as a result of the incorrect esign and fluctuations in the groundwater pressure under the foundation. The cyclic presence and absence of water rusted the steel reinforcement, and the sulfates in the clay soil caused formation of ettringite in the concrete. Plastic hinges formed in the slab and settlements occurred, causing damage to the beams. The situation is still in progress and may lead to the collapse of the structure under normal service conditions. The geotechnical and structural investigations performed to survey and ass…
A machine learning approach to determine airport asphalt concrete layer moduli using heavy weight deflectometer data
2021
An integrated approach based on machine learning and data augmentation techniques has been developed in order to predict the stiffness modulus of the asphalt concrete layer of an airport runway, from data acquired with a heavy weight deflectometer (HWD). The predictive model relies on a shallow neural network (SNN) trained with the results of a backcalculation, by means of a data augmentation method and can produce estimations of the stiffness modulus even at runway points not yet sampled. The Bayesian regularization algorithm was used for training of the feedforward backpropagation SNN, and a k-fold cross-validation procedure was implemented for a fair performance evaluation. The testing p…