Research

Jump to: Review

19 pages, 5185 KiB

Open AccessArticle

Experimental Studies and Numerical Simulations of FRP Poles Failure in the Area of Inspection Hole

by

Filip Broniewicz

,

Tadeusz Chyży

and

Krzysztof Robert Czech

Materials 2023, 16(6), 2238; https://doi.org/10.3390/ma16062238 - 10 Mar 2023

Viewed by 679

Abstract

Glass fiber-reinforced polymer (GFRP) utility poles are becoming more widespread in European countries. To ensure the integrity and safety of poles, it is necessary to carefully examine their structural features. The purpose of this paper is to present the numerical model of a [...] Read more.

Glass fiber-reinforced polymer (GFRP) utility poles are becoming more widespread in European countries. To ensure the integrity and safety of poles, it is necessary to carefully examine their structural features. The purpose of this paper is to present the numerical model of a column made with the engineering simulation software ANSYS and to compare the experimentally determined values of the stresses that lead to column failure close to the inspection hole with the results obtained using the numerical model. The critical buckling and failure loads for GFRP poles, as well as the associated modes of failure, were correctly predicted by the finite element method used in this study. Failure occurred in the middle of the inspection hole’s longer edge at a stress level of 220–250 MPa. A comparison of the stress using the ANSYS simulation software that led to the destruction of the column with those measured experimentally using strain gauges revealed a good agreement between their values. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

11 pages, 5913 KiB

Open AccessArticle

Intercolonial Microdamage and Cracking Micromechanisms during Wire Drawing of Pearlitic Steel

by

Jesús Toribio

,

Francisco-Javier Ayaso

and

Rocío Rodríguez

Materials 2023, 16(5), 1822; https://doi.org/10.3390/ma16051822 - 22 Feb 2023

Cited by 1 | Viewed by 793

Abstract

This paper studies the drawing-induced intercolonial microdamage (ICMD) in pearlitic microstructures. The analysis was performed from the direct observation of the microstructure of the progressively cold-drawn pearlitic steel wires associated with the distinct steps (cold-drawing passes) of a real cold-drawing manufacturing [...] Read more.

This paper studies the drawing-induced intercolonial microdamage (ICMD) in pearlitic microstructures. The analysis was performed from the direct observation of the microstructure of the progressively cold-drawn pearlitic steel wires associated with the distinct steps (cold-drawing passes) of a real cold-drawing manufacturing scheme, constituted by seven cold-drawing passes. Three types of ICMD were found in the pearlitic steel microstructures, all affecting two or more pearlite colonies, namely: (i) intercolonial tearing; (ii) multi-colonial tearing; and (iii) micro-decolonization. The ICMD evolution is quite relevant to the subsequent fracture process of cold-drawn pearlitic steel wires, since the drawing-induced intercolonial micro-defects act as weakest links or fracture promoters/initiators, thereby affecting the microstructural integrity of the wires. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

15 pages, 4674 KiB

Open AccessArticle

The Mechanical Characteristics of High-Strength Self-Compacting Concrete with Toughening Materials Based on Digital Image Correlation Technology

by

,

,

,

,

and

Materials 2023, 16(4), 1695; https://doi.org/10.3390/ma16041695 - 17 Feb 2023

Cited by 2 | Viewed by 917

Abstract

Brittle fracture is a typical mechanical characteristic of high-strength self-compacting concrete, and the research on its toughening modification remains the highlight in the engineering field. To understand the effect of toughening materials (including polymer latex powders, rubber particles, and polyethylene fibers) on the [...] Read more.

Brittle fracture is a typical mechanical characteristic of high-strength self-compacting concrete, and the research on its toughening modification remains the highlight in the engineering field. To understand the effect of toughening materials (including polymer latex powders, rubber particles, and polyethylene fibers) on the mechanical behavior of C80 high-strength self-compacting concrete under static loading, the failure mode, mechanical strength, strain field, and crack opening displacement (COD) of prepared high-strength self-compacting concrete under compressive, splitting, and flexural loads were studied based on digital image technology (DIC). The corresponding mechanism is also discussed. The results show that the hybrid of polymer latex powders, rubber particles, and polyethylene fibers can increase the crack path and inhibit the development of macrocracks in concrete, thus turning the fracture behavior of concrete from brittle to ductile. The addition of toughening materials reduced the compressive and flexural strengths of high-strength self-compacting concrete, but it increased the splitting strength. DIC showed that the incorporation of toughening materials promoted the redistribution of strain and reduced the degree of strain concentration in high-strength self-compacting concrete. The evolution of COD in high-strength self-compacting concrete can be divided into two stages, including the linear growth stage and the plastic yield stage. The linear growth stage can be extended by incorporating toughening materials. The COD and energy absorption capacity of concrete were enhanced with the addition of toughening materials, and the best enhancement was observed with the hybrid of polymer latex powders, rubber particles, and polyethylene fibers. Overall, this research provides a reference for exploring effective technical measures to improve the toughness of high-strength self-compacting concrete. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

14 pages, 10131 KiB

Open AccessArticle

Effect of the Internal Humidity of Concrete on Frost Resistance and Air Void Structure under Different Low Temperature Conditions

by

,

,

,

,

,

and

Materials 2022, 15(15), 5225; https://doi.org/10.3390/ma15155225 - 28 Jul 2022

Viewed by 885

Abstract

From the perspective of combining macroscopic and microscopic properties, this paper simulates the freeze–thaw cycle process at different freezing low temperatures based on the climate simulation equipment and by setting the curing conditions with different temperatures and relative humidity to produce different moisture [...] Read more.

From the perspective of combining macroscopic and microscopic properties, this paper simulates the freeze–thaw cycle process at different freezing low temperatures based on the climate simulation equipment and by setting the curing conditions with different temperatures and relative humidity to produce different moisture conditions in concrete. The frost resistance properties and microscopic air void performance of concrete with different internal water content under different freezing low temperatures in freeze–thaw cycles were systematically studied. The results show that the higher the internal water content of concrete, the more obvious the mass loss rate and dynamic elastic modulus loss of concrete in the freeze–thaw process, and the more serious the deterioration of the air void parameter performance of the air-entraining agent introduced into concrete, which is manifested as the average bubble diameter and bubble spacing factor become larger and the bubble specific surface area decreases. In addition, in the case of the same internal moisture content of concrete, the freezing temperature used in the freeze–thaw cycle also has an important impact on the frost resistance of concrete and air void parameters; the lower the freezing temperature used, the more significant the decline in the frost resistance of concrete, the more obvious the deterioration of air void parameters. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

20 pages, 5437 KiB

Open AccessArticle

Research on Hyperparameter Optimization of Concrete Slump Prediction Model Based on Response Surface Method

by

,

,

,

,

,

and

Materials 2022, 15(13), 4721; https://doi.org/10.3390/ma15134721 - 05 Jul 2022

Cited by 3 | Viewed by 1227

Abstract

In this paper, eight variables of cement, blast furnace slag, fly ash, water, superplasticizer, coarse aggregate, fine aggregate and flow are used as network input and slump is used as network output to construct a back-propagation (BP) neural network. On this basis, the [...] Read more.

In this paper, eight variables of cement, blast furnace slag, fly ash, water, superplasticizer, coarse aggregate, fine aggregate and flow are used as network input and slump is used as network output to construct a back-propagation (BP) neural network. On this basis, the learning rate, momentum factor, number of hidden nodes and number of iterations are used as hyperparameters to construct 2-layer and 3-layer neural networks respectively. Finally, the response surface method (RSM) is used to optimize the parameters of the network model obtained previously. The results show that the network model with parameters obtained by the response surface method (RSM) has a better coefficient of determination for the test set than the model before optimization, and the optimized model has higher prediction accuracy. At the same time, the model is used to evaluate the influencing factors of each variable on slump. The results show that flow, water, coarse aggregate and fine aggregate are the four main influencing factors, and the maximum influencing factor of flow is 0.875. This also provides a new idea for quickly and effectively adjusting the parameters of the neural network model to improve the prediction accuracy of concrete slump. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

26 pages, 9487 KiB

Open AccessArticle

Numerical Simulation Study on Factors Influencing Anti-Explosion Performance of Steel Structure Protective Doors under Chemical Explosion Conditions

by

,

,

,

,

,

and

Materials 2022, 15(11), 3880; https://doi.org/10.3390/ma15113880 - 29 May 2022

Cited by 2 | Viewed by 1090

Abstract

To study the mechanical deformation characteristics and anti-explosion mechanisms of steel-structure protective doors under chemical explosion shock wave loads, numerical simulations of loads and door damage were carried out using the AUTODYN and LS-DYNA software based on model tuning with actual field test [...] Read more.

To study the mechanical deformation characteristics and anti-explosion mechanisms of steel-structure protective doors under chemical explosion shock wave loads, numerical simulations of loads and door damage were carried out using the AUTODYN and LS-DYNA software based on model tuning with actual field test results. The finite element simulation results were compared with the test results to verify the accuracy of the simulation model and material parameters. A parametric analysis was carried out on the influencing factors of the anti-explosion performance of the beam–plate steel structure protective door under typical shock wave loads. The impact of the material strength and geometry of each part of the protective door on its anti-explosion performance was studied. The results showed that the protective door sustained a uniform shock wave load and that increasing the steel strength of the skeleton could significantly reduce the maximum response displacement of the protective door. The steel strength increase of the inner and outer panels had little or a negligible effect on the anti-explosion performance of the protective door. The geometric dimensions of different parts of the protective door had different effects on the anti-explosion performance. Increasing the skeleton height had the most significant effect on the anti-explosion performance. The skeleton’s I-steel flange thickness and the inner and outer panel thicknesses had less significant effects. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

11 pages, 1997 KiB

Open AccessArticle

Strength Properties of Structural Glulam Manufactured from Pine (Pinus sylvestris L.) Side Boards

by

,

,

,

,

and

Materials 2021, 14(23), 7312; https://doi.org/10.3390/ma14237312 - 29 Nov 2021

Cited by 3 | Viewed by 1499

Abstract

The aim of this study was to assess the static bending strength of pine glulam manufactured when obtaining the main yield, i.e., structural timber or timber to be used in the production of structural glulam. Analyses were conducted on pine timber harvested from [...] Read more.

The aim of this study was to assess the static bending strength of pine glulam manufactured when obtaining the main yield, i.e., structural timber or timber to be used in the production of structural glulam. Analyses were conducted on pine timber harvested from three different locations in Poland. Two beam variants were manufactured, differing in the timber arrangement, horizontal vs. vertical. It was shown that the static bending strength of beams manufactured in the vertical timber arrangement variant is slightly higher than that of beams produced from horizontally arranged layers, with the latter beams characterised by a smaller confidence interval for this strength. Moreover, it was found that the difference in the value of the 5th percentile for both beam types is slight and both beam types are considered to exhibit a high bending strength of over 40 N/mm². Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures

Figure 1

Review

Jump to: Research

15 pages, 3250 KiB

Open AccessReview

A Review of Research on Mechanical Properties and Durability of Concrete Mixed with Wastewater from Ready-Mixed Concrete Plant

by

,

,

,

,

and

Materials 2022, 15(4), 1386; https://doi.org/10.3390/ma15041386 - 13 Feb 2022

Cited by 8 | Viewed by 1990

Abstract

The wastewater from ready-mixed concrete plants is currently being recycled as concrete mixing water. It has attracted significant attention from the construction industry and researchers since it promotes sustainable development through environmental protection, energy-saving, and emissions reduction. This article review first introduces the [...] Read more.

The wastewater from ready-mixed concrete plants is currently being recycled as concrete mixing water. It has attracted significant attention from the construction industry and researchers since it promotes sustainable development through environmental protection, energy-saving, and emissions reduction. This article review first introduces the nature of wastewater in ready-mixed concrete plants in different regions. Then the effects of solid content in water on various properties of concrete, including working performance, durability and microscopic properties, are reviewed, respectively, when concrete is mixed with wastewater instead of tap water. Furthermore, the microscopic mechanism of action in concrete mixing with wastewater is discussed, and future work is recommended. This review provides fundamentals on the study of the properties of concrete after wastewater is mixed into concrete. Full article

(This article belongs to the Special Issue Strength and Fracture Mechanism of Construction Materials and Structural Components)

► Show Figures