Search

In the event of a fire within a tunnel, the rapid and substantial increase in temperature can prompt swift fractures within the concrete lining. This situation can severely compromise the structural load-bearing capacity and overall safety of the tunnel. The intricate interplay of factors within the tunnel, including temperature, humidity, and pore pressure, necessitates the adoption of a thermo-hydro coupled model for comprehensive analysis. However, these highly coupled models exhibit profoundly nonlinear characteristics that cannot be readily solved through analytical means. In this study, a Physics-informed neural network (PINN) is harnessed to address this intricate multi-field coupled issue. Neural networks possess a significant advantage in their capacity to autonomously differentiate and directly capture variations within the spatiotemporal domain. Through a comparison with experimental results, the proposed method's reliability is effectively demonstrated. The research findings hold the potential to significantly aid engineering professionals in swiftly conducting fire resistance assessments and risk evaluations for tunnels, whether they are under construction or already in operation. [ABSTRACT FROM AUTHOR]

This paper presents an application of the Boundary Element Method (BEM) in engineering to numerically analyse the thermal behaviour of structures executed by layers that present different temperatures at the time of overlapping and/or that present some type of internal heat generation. This type of phenomenon occurs, for example, in large concrete structures, where the structure has its temperature altered due to the hydration reaction of the cement during the concrete curing process. Using the developed formulation, it is possible to simulate the temperature field at all stages of the construction process and in different situations by changing the thermophysical parameters, taking into account the thermal influence of one layer on the others and on the structure as a whole. With the simulation results, it is also possible to define the deposition time between the layers of the structure, which is important information for cases in which the temperature variation may imply the appearance of thermal stresses, for example, or when the maximum temperature reached do not exceed a certain limit. The cases presented were directed to concrete structures, mainly roller-compacted concrete (RCC) dams, whose details of the construction process, as well as the heat diffusion process during the concrete curing process and the entire formulation of the boundary element, are presented below. [ABSTRACT FROM AUTHOR]

This study presents a BEM multi-scale modelling to analyse the bending problem of concrete plates. The concrete microstructure is represented by the Representative Volume Element (RVE), in which the mortar matrix behaviour is governed by the Mohr-Coulomb criterion, the aggregates are considered elastics and the mortar porosity is modelled by defining voids into its domain. Moreover, the microcracking process at ITZ (Interfacial Transition Zone) is modelled by defining additional cohesive-contact finite elements on interfaces between mortar and aggregates. To define the RVE microstructure and the parameters of its phases, we consider a concrete whose experimental curve in compression is known. We show that, for the same volume fraction of inclusions and voids, a RVE with reduced number of aggregates and voids can reproduce the experimental results for compression predominant regimes. But for plate bending analysis, the microstructure and mainly the modelling of the microcracking process at ITZ have enormous influence on the plate mechanical behaviour. The results are also compared to a multi-scale formulation considering the FEM (Finite Element Method) at micro-scale, showing that the proposed model is much faster than the coupled BEM/FEM model. [ABSTRACT FROM AUTHOR]

A report from the National Research Council (CNR) highlights the need for the reshoring of fine chemical and pharmaceutical productions due to prolonged shortages of active pharmaceutical ingredients (APIs) in many countries. The global supply chains have been disrupted during the COVID-19 crisis and the ongoing Red Sea crisis, exacerbating the situation. The study examines the economic and policy aspects of reshoring API production to Europe, as well as the industrial uptake of continuous manufacturing in fine chemicals production in China and India. The research concludes with three main findings. Financial support for the research came from the Ministero delle Imprese e del Made in Italy - EU NextGenerationEU - M2C2 Investment 3.5. [Extracted from the article]

In this paper, the elastic-plastic analysis of cantilever beam and the Reinforced Concrete (RC) column-Steel (S) beam connection are studied using the Radial Basis Function- Finite Difference (RBF-FD) method. A direct method using bilinear nodes is proposed to deal with the instability caused by the first derivative calculation in the traditional RBF-FD method. Based on the idea of gradient projection method, the improved RBF-FD method is further applied to the multi-domain material nonlinearity. Numerical results are validated with the finite element method software (COMSOL). [ABSTRACT FROM AUTHOR]

The article discusses the economic and political power grab by Egypt's military under President El-Sisi, resulting in major changes to the Egyptian economy that benefit the military and leave the poor significantly more destitute. The author argues that these systemic changes have left no legal or political channels for popular anger to be absorbed, potentially leading to a rapid implosion of the regime. The article provides an unsettling overview of the situation in Egypt and highlights the negative impact on civil society and the public good. [Extracted from the article]

The article reports that 3D printing is a production technology that can fabricate components, parts and more from a digital blueprint. Through this technology products including medical devices, replicated museum pieces, shoes, food and more are "printed," layer by layer, using materials such as polymers, metals and ceramics. Generally, 3D printing begins with the creation of a digital 3D model of the object to be printed using certain software applications.

We begin the article by summarizing some key developments in the field of Peridynamics (PD) and arrive at a conclusion that two schools of PD are emerging in recent years. One school takes a more traditional view of PD as a model of a nonlocal continuum, while another approaches PD as a discretization methodology for local continua where the nonlocality is reduced under mesh refinement. Adhering to the latter viewpoint, we develop a PD formulation using the now classical, yet continuously evolving Microplane constitutive model (M7) developed for the failure analysis of concrete materials. We show how to incorporate the M7 model into correspondence-based PD (also known as the non-ordinary state-based PD) and validate the formulation using an extensive set of classical fracture tests. We also propose an extension of the M7 model to handle concrete fracture and fragmentation in the PD context. [ABSTRACT FROM AUTHOR]

Pore structure is an important factor that determines concrete's macroscopic performance, including strength, freezing-thaw susceptibility, and thermal and transport properties. Welldispersed air voids protect concrete from destruction during freeze-thaw processes, as well as from thermal stresses, but at the cost of reducing its strength. Therefore, measuring the characteristics of air voids in concrete is important to assess its strength and durability. The development of technologies that can measure the air voids in concrete quickly, nondestructively and accurately are important for this reason. In this paper, a new ultrasonic technology was developed to measure the air void distribution in concrete. The theoretical basis of this technology is an advanced ultrasonic wave scattering model in complex structural materials. The model can account for the attenuation effects of multiple-sized air voids. The air voids are treated as elastic scatterers or cavities, two extreme conditions for their actual physical effects. The total attenuations are derived by superimposing the wave attenuation due to air void scatterers, coarse aggregates and the viscoelastic cement matrix. To validate this model, experiments were conducted to measure the wave attenuation curve in cement and concrete specimens. Inversion analyses were conducted to match the predicted ultrasonic wave attenuation against the measured attenuation. The inversion parameters were used to determine the air void distribution by assuming they follow a logarithmicnormal distribution, which obtained reasonable results. [ABSTRACT FROM AUTHOR]

At present, the core test is commonly employed for testing the properties of aging concrete structures. This test, which requires coring concrete samples for subsequent offsite laboratory testing, is somewhat destructive and limited to taking samples from only a few locations. This paper reports an optical technique based on shearography for nondestructive testing of concrete properties. The technique does not require coring and therefore allows testing on many structural locations to be performed. The preliminary results have demonstrated that the technique has great potential for development into a practical tool for testing of concrete modulus of elasticity and concrete strength. [ABSTRACT FROM AUTHOR]

Abstract: We proposed a constitutive model for the two-dimensional analysis of concrete structures. The proposed model treats concrete as an orthotropic nonlinear material. The equivalent principal strain based approach allows the model to represent the mechanical behavior of concrete by using two equivalent uniaxial stress–strain relations. The biaxial behavior of concrete is described using the concept of current strength in a principal stress space. The fracture energy method is incorporated to solve the problem of mesh non-objectivity, and the concept of current fracture energy gives an improved description of the post-peak behavior of concrete. Secant-stiffness-based finite-element formulations are implemented in a smeared rotating crack fashion. Correlative studies using available experimental test results are presented to demonstrate the performance of the model at a structural level. [Copyright &y& Elsevier]

Focuses on the advantages of maturity testing in measuring strength-dependent construction activities. Formula for the maturity concept technique; Basis for determining concrete strength; Results of using maturity testing in the Transcontinental Street Panel Replacement project by Fleming Construction.

Discusses the problems concerning plain and decorative concrete. Importance of air entrainment to concrete surface and finishing; Causes of concrete surface wear and crack; Influence of curing on color, wear and dusting of concrete.

Deals with the experiment of Federal Highway Administration (FHWA) that evaluates the effectiveness of the penetrant in reducing the permeability of hardened concrete and the depth of penetration of the sealant into the concrete. Functions of sealer and penetrants; Study design in evaluating the concrete; Results of the experiment; Discussion of the experiment and conclusions.

Focuses on the alteration of samples extracted from concrete structures for laboratory study. Usefulness of cores as a sample; Impact of the exposure to water and air on the concrete; Occurrence of the alteration during sample preparation; Detection of rapid cement paste carbonation during laboratory studies.

SACP to stay in alliance with ruling African National Congress The South African Communist Party said it will contest future elections independent of its ally, the ruling African National Congress. The SACP, which has a political alliance with the ANC and the Congress of South African Trade Unions, reaffirmed its decision to contest state power. [Extracted from the article]

The article offers civil engineering research news briefs as of June 2017 that includes introduction of technique by the U.S. National Institute of Standards and Technology (NIST) for analysis of steel in concrete; and usage of balloon for assessment of climate change by the Harvard University.

Focuses on the concrete mix designs presented at the Aggregate Research Industries for the ICF construction project. Analysis of the performance characteristics of the concrete; Range of costs of the concrete per cubic yard; Contents of the concrete.

The article informs that the Electric Power Research Institute (EPRI) along with the New York Power Authority (NYPA), Exelon Corp. and the Southwest Research Institute has demonstrated the advanced inspection techniques of concrete structures by a robotic crawler. It mentions that the demonstration of robotic equipments tool place at the Niagara Hydroelectric Power Plant for a EPRI's research on concrete aging.

The article looks at a study in "Journal of the American Ceramic Society" by researchers Paulo J. M. Monteiro and Marie Jackson and team on the mineralogical analysis of a concrete ancient Roman breakwater in Naples, Italy, finding the cementing compound calcium-aluminum-silicate-hydrate (C-A-S-H).

The article discusses the importance of testing concrete hardness prior to polishing process. It states that conducting an assessment of the hardness of the concrete surface can help contractors boost their productivity. Moreover, it offers some tips for performing a scratch test and selecting a diamond polishing tool.

The article provides rules which clarify the common misconception whenever a concrete floats and trowels. These involve the drying surface of the slab, the application of water during the concrete's floating and finishing, and the availability of a high-pressure hose and a bump cutter. It also notes that a finisher must deal simultaneously its three factors under all conditions such as its weight rate setting, the drying rate of its surface, and the compacting capability of the power trowel.

The article presents a study on the special property of concrete that absorbs carbon dioxide in the U.S. According to Liv Haselbach, civil and environmental engineering professor at Washington State University, her team can be able to accelerate carbon dioxide absorbing, if it knows what is inside the concrete. She adds that if her team can facilitate the carbon coming back in, it can make carbon neutral.

Presents brief descriptions of reports published by the Office of Research, Development and Technology of the U.S. Federal Highway Administration, as of November 2002. 'Identification and Evaluation of Automobile Driver Errors: Overview and Recommendations'; 'Guidelines for Detection, Analysis, and Treatment of Materials-Related Distress in Concrete Pavements'; 'Transport Properties and Durability of Concrete: Literature Review and Research Plan.'

Provides information on high-performance concrete (HPC) improved by the engineers at the University of Cincinnati. Advantage of the HPC; Benefits of the concrete; Results of test conducted on the concrete.