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23 pages, 7073 KiB

Open AccessArticle

Risk Assessment of Overturning of Freestanding Non-Structural Building Contents in Buckling-Restrained Braced Frames

by Atsushi Suzuki, Susumu Ohno and Yoshihiro Kimura

Buildings 2024, 14(10), 3195; https://doi.org/10.3390/buildings14103195 - 8 Oct 2024

Viewed by 493

Abstract

The increasing demand in structural engineering now extends beyond collapse prevention to encompass business continuity planning (BCP). In response, energy dissipation devices have garnered significant attention for building response control. Among these, buckling-restrained braces (BRBs) are particularly favored due to their stable hysteretic [...] Read more.

The increasing demand in structural engineering now extends beyond collapse prevention to encompass business continuity planning (BCP). In response, energy dissipation devices have garnered significant attention for building response control. Among these, buckling-restrained braces (BRBs) are particularly favored due to their stable hysteretic behavior and well-established design provisions. However, BCP also necessitates the prevention of furniture overturning—an area that remains quantitatively underexplored in the context of buckling-restrained braced frames (BRBFs). Addressing this gap, this research designs BRBFs using various design criteria and performs incremental dynamic analysis (IDA) with artificially generated seismic waves. The results are compared with previously developed fragility curves for furniture overturning under different BRB design conditions. The findings demonstrate that the fragility of furniture overturning can be mitigated by a natural frequency shift, which alters the threshold of critical peak floor acceleration. These results, combined with hazard curves obtained from various locations across Japan, quantify the mean annual frequency of furniture overturning. The study reveals that increased floor acceleration in stiffer BRBFs can lead to a 3.8-fold higher risk of furniture overturning compared to frames without BRBs. This heightened risk also arises from the greater hazards at shorter natural periods due to stricter response reduction demands. The probabilistic risk analysis, which integrates fragility and hazard assessments, provides deeper insights into the evaluation of BCP. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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14 pages, 8521 KiB

Open AccessArticle

Performance Assessment of Wood-Based Composite Materials Subjected to High Temperatures

by Ruxandra Irina Erbașu, Andrei-Dan Sabău, Daniela Țăpuși and Ioana Teodorescu

Buildings 2024, 14(10), 3177; https://doi.org/10.3390/buildings14103177 - 5 Oct 2024

Viewed by 585

Abstract

This paper is based on research placed within the broader framework of the growing environmental impact requirements of building materials. Given this context, wood-based composite materials have emerged as a promising and innovative solution for structural elements. The current work aims to define [...] Read more.

This paper is based on research placed within the broader framework of the growing environmental impact requirements of building materials. Given this context, wood-based composite materials have emerged as a promising and innovative solution for structural elements. The current work aims to define a system for testing the mechanical behavior of glued laminated timber elements when exposed to high temperatures, in the neighborhood of the pyrolytic decomposition of materials. These tests monitor the transient behavior of the composite material and characterize the parameters involved in the thermo-mechanical analysis of elements constructed using this type of engineered wood product. The tests are used for the calibration of the material models involved in the numerical analysis and for the analysis of potential prototypes, considering the transient thermal load and heat propagation through the materials. By taking such tests, benchmark models and laboratory procedures are defined that can be used in the future to evaluate different materials, existing or new, and material combinations used to construct such a composite. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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31 pages, 25322 KiB

Open AccessArticle

Study on the Bond Performance of Epoxy Resin Concrete with Steel Reinforcement

by Peiqi Chen, Yueqiang Li, Xiaojie Zhou, Hao Wang and Jie Li

Buildings 2024, 14(9), 2905; https://doi.org/10.3390/buildings14092905 - 14 Sep 2024

Viewed by 734

Abstract

Epoxy resin concrete, characterized by its superior mechanical properties, is frequently utilized for structural reinforcement and strengthening. However, its application in structural members remains limited. In this paper, the bond–slip behavior between steel reinforcement and epoxy resin concrete was investigated using a combination [...] Read more.

Epoxy resin concrete, characterized by its superior mechanical properties, is frequently utilized for structural reinforcement and strengthening. However, its application in structural members remains limited. In this paper, the bond–slip behavior between steel reinforcement and epoxy resin concrete was investigated using a combination of experimental research and finite element analysis, with the objective of providing data support for substantiating the expanded use of epoxy resin concrete in structural members. The research methodology included 18 center-pullout tests and 14 finite element model calculations, focusing on the effects of variables such as epoxy resin concrete strength, steel reinforcement strength, steel reinforcement diameter and protective layer thickness on bond performance. The results reveal that the bond strength between epoxy resin concrete and steel reinforcement significantly surpasses that of ordinary concrete, being approximately 3.23 times higher given the equivalent strength level of the material; the improvement in the strength of both the epoxy resin concrete and steel reinforcement are observed to marginally increase the bond stress. Conversely, an increase in the diameter of the steel reinforcement and a reduction in the thickness of the protective layer of the concrete can lead to diminished bond stress and peak slip. Particularly, when the steel reinforcement strength is below 500 MPa, it tends to reach its yield strength and may even detach during the drawing process, indicating that the yielding of the steel reinforcement occurs before the loss of bond stress. In contrast, for a steel reinforcement strength exceeding 500 MPa, yielding does not precede bond stress loss, resulting in a distinct form of failure described as scraping plough type destruction. Compared to ordinary concrete, the peak of the epoxy resin concrete and steel reinforcement bond stress–slip curve is more pointed, indicating a rapid degradation to maximum bond stress and exhibiting a brittle nature. Overall, these peaks are sharper than those of ordinary concrete, indicating a rapid decline in bond stress post-peak, reflective of its brittle characteristics. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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15 pages, 9021 KiB

Open AccessArticle

A New Methodology to Estimate the Early-Age Compressive Strength of Concrete before Demolding

by Bayarjavkhlan Narantogtokh, Tomoya Nishiwaki, Fumiya Takasugi, Ken Koyama, Timo Lehmann, Anna Jagiello, Félix Droin and Yao Ding

Buildings 2024, 14(7), 2099; https://doi.org/10.3390/buildings14072099 - 9 Jul 2024

Viewed by 1002

Abstract

Non-destructive testing has many advantages, such as the ability to obtain a large number of data without destroying existing structures. However, the reliability of the estimation accuracy and the limited range of applicable targets remain an issue. This study proposes a novel pin [...] Read more.

Non-destructive testing has many advantages, such as the ability to obtain a large number of data without destroying existing structures. However, the reliability of the estimation accuracy and the limited range of applicable targets remain an issue. This study proposes a novel pin penetration test method to determine the early-age compressive strength of concrete before demolding. The timing of demolding and initial curing is determined according to the strength development of concrete. Therefore, it is important to determine the compressive strength at an early age before demolding at the actual construction site. The applicability of this strength estimation methodology at actual construction is investigated. Small test holes (12 mm in diameter) are prepared on the mold surface in real construction sites and mock-up specimens in advance. The pin is penetrated into these test holes to obtain the relationship between the compressive strength and the penetration depth. As a result, it is confirmed that the pin penetration test method is suitable for measuring the early-age compressive strength at the actual construction site. This allows the benchmark values for compressive strength, necessary to avoid early frost damage, to be directly verified on the concrete structural members at the construction site. For instance, the compressive strengths of greater than 5 MPa and 10 MPa can be confirmed by the penetration depths benchmark values of 8.0 mm and 6.7 mm or less, respectively. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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37 pages, 13271 KiB

Open AccessArticle

Egg White and Eggshell Mortar Reinforcing a Masonry Stone Bridge: Experiments on Mortar and 3D Full-Scale Bridge Discrete Simulations

by Murat Cavuslu and Emrah Dagli

Buildings 2024, 14(6), 1672; https://doi.org/10.3390/buildings14061672 - 5 Jun 2024

Cited by 1 | Viewed by 855

Abstract

In this study, experimental and numerical investigations were conducted to examine the time-dependent creep and earthquake performance of the historical Plaka stone bridge, which was constructed in 1866 in Arta, Greece. During the original construction of the bridge in 1866, Khorasan mortar with [...] Read more.

In this study, experimental and numerical investigations were conducted to examine the time-dependent creep and earthquake performance of the historical Plaka stone bridge, which was constructed in 1866 in Arta, Greece. During the original construction of the bridge in 1866, Khorasan mortar with an egg white additive was used between the stone elements. Furthermore, when the bridge underwent restoration in 2015, Khorasan mortar with an eggshell additive was employed between the stone elements. Consequently, two distinct 3D finite-difference models were developed for this study. In the first bridge model, egg white was used in the Khorasan mortar, replacing water at various proportions of 0%, 25%, 50%, 75%, and 100%. In contrast, for the second model, eggshell was incorporated into the Khorasan mixture at percentages of 25%, 50%, 75%, and 100%, relative to the lime amount. Subsequently, the mortars were subjected to curing periods of 1 day, 7 days, and 28 days, and their mechanical properties were determined through unconfined compression strength experiments. Taking into account the determined strengths of the mortars, the kn and ks stiffness values of the interface elements between the stone elements and Khorasan mortar were calculated. In the 3D model, each stone element was individually represented, resulting in a total of 1,849,274 stone elements being utilized. Non-reflecting boundary conditions were applied to the edge boundaries of the bridge model, and the Burger creep and Mohr–Coulomb material models was employed for time-dependent creep and seismic analyses, respectively. Subsequently, time-dependent creep analyses were conducted on the bridge, and seismic events that occurred in the region where the bridge was located were simulated to assess their impact. Based on the results of the time-dependent creep and seismic analyses, we observed that the use of 50% eggshell-mixed Khorasan mortar between the stone elements had a positive influence on the earthquake and creep behaviors of both restored and yet-to-be-restored historical bridges. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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23 pages, 5740 KiB

Open AccessArticle

Evaluation of Rotation Capacity and Bauschinger Effect Coefficient of I-Shaped Beams Considering Loading Protocol Influences

by Yoshihiro Kimura

Buildings 2024, 14(5), 1376; https://doi.org/10.3390/buildings14051376 - 11 May 2024

Viewed by 711

Abstract

Recent catastrophic earthquake events have reinforced the necessity of evaluating the seismic performance of buildings. Notably, the buildings can go into the plastic phase during a striking earthquake disaster. Under this condition, the current design codes assume seismic response reduction by virtue of [...] Read more.

Recent catastrophic earthquake events have reinforced the necessity of evaluating the seismic performance of buildings. Notably, the buildings can go into the plastic phase during a striking earthquake disaster. Under this condition, the current design codes assume seismic response reduction by virtue of the energy dissipation capacity of the structural members. In the strong-column–weak-beam design, which involves I-shaped beams and boxed columns, the mechanism is defined as a standard design scheme to prevent the building from collapsing. Therefore, energy dissipation relies highly on the I-shaped beam performance. However, the I-shaped beam performance can differ depending on the loading history experienced, whereas this effect is untouched in the prevailing evaluation equation. Hence, this study first performs cyclic loading tests of 11 specimens using different loading protocols. The experimental results clarify the fluctuation in the structural performance of I-shaped beams depending on the applied loading hysteresis, proving the necessity of considering the stress history for proper assessment. Furthermore, the database of experimental results is constructed based on the previous experimental studies. Ultimately, the novel evaluation equation is proposed to reflect the influences of the loading protocol. This equation is demonstrated to effectively assess the member performance retrieved from the experiment of 65 specimens, comprising 11 specimens from this investigation and 54 specimens from the database. The width–thickness ratio, shear span-to-depth ratio, and loading protocols are utilized as the evaluation parameters. Moreover, the prediction equation of the Bauschinger effect coefficient is newly established to convert the energy dissipation capacity under monotonically applied force into hysteretic energy dissipation under the cyclic forces. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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15 pages, 12453 KiB

Open AccessArticle

A Study on the Mechanical Characteristics and Wheel–Rail Contact Simulation of a Welded Joint for a Large Radio Telescope Azimuth Track

by Xiao Chen, Ruihua Yin, Zaitun Yang, Huiqing Lan and Qian Xu

Buildings 2024, 14(5), 1300; https://doi.org/10.3390/buildings14051300 - 5 May 2024

Viewed by 804

Abstract

The azimuth track is an important component of the radio telescope wheel–rail system. During operation, the azimuth track is inevitably subject to phenomena such as track wear, track fatigue cracks, and impact damage to welded joints, which can affect observation accuracy. The 110 [...] Read more.

The azimuth track is an important component of the radio telescope wheel–rail system. During operation, the azimuth track is inevitably subject to phenomena such as track wear, track fatigue cracks, and impact damage to welded joints, which can affect observation accuracy. The 110 m QiTai radio telescope (QTT) studied in this paper is the world’s largest fully steerable radio telescope at present, and its track will bear the largest load ever. Since the welded joint of an azimuth track is the weakest part, an innovative welding method (multi-layer and multi-pass weld) is adopted for the thick welding section. Therefore, it is necessary to study the contact mechanical properties between the wheel and the azimuth track in this welded joint. In this study, tensile tests based on digital image correlation technology (DIC) and Vickers hardness tests are carried out in the metal zone (BM), heat-affected zone (HAZ), modified layer, and weld zone (WZ) of the welded joint, and the measured data are used to fit the elastic–plastic constitutive model for the different zones of the welded joint in the azimuth track. Based on the constitutive model established, a nonlinear finite element model is built and used to simulate the rolling mechanical performance between the wheel and azimuth track. Through the analysis of simulated data, we obtained the stress distribution of the track under different pre-designed loads and identified the locations most susceptible to damage during ordinary working conditions, braking conditions, and start-up conditions. The result can provide a significant theoretical basis for future research and for the monitoring of large track damage. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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25 pages, 9755 KiB

Open AccessArticle

Rotational Stiffening Performance of Roof Folded Plates in Torsion Tests and the Stiffening Effect of Roof Folded Plates on the Lateral Buckling of H Beams in Steel Structures

by Yuki Yoshino and Yoshihiro Kimura

Buildings 2024, 14(4), 1158; https://doi.org/10.3390/buildings14041158 - 19 Apr 2024

Cited by 1 | Viewed by 837

Abstract

Non-structural members, such as roofs and ceilings, become affixed to main beams that are known as structural members. When such main beams experience bending or compressive forces that lead to lateral buckling, non-structural members may act to restrain the resulting lateral buckling deformation. [...] Read more.

Non-structural members, such as roofs and ceilings, become affixed to main beams that are known as structural members. When such main beams experience bending or compressive forces that lead to lateral buckling, non-structural members may act to restrain the resulting lateral buckling deformation. Nevertheless, neither Japanese nor European guidelines advocate for the utilization of non-structural members as lateral buckling stiffeners for beams. Additionally, local buckling ensues near the bolt apertures in the beam–roof folded plate connection due to the torsional deformation induced by the lateral buckling of the H beam, thereby reducing the rotational stiffness of the roof folded plate to a percentage of its ideal stiffness. This paper conducts torsional experiments on roof folded plates, and with various connection methods between these plates and the beams, to comprehend the deformation mechanism of roof folded plates and the relationship between their rotational stiffness and the torsional moment. Then, the relationship between the demand values against restraining the lateral buckling of the main beam and the experimentally determined bearing capacity of the roof folded plate is elucidated. Results indicate the efficacy of utilizing the roof folded plate as a continuous brace. The lateral buckling design capacity of H beams that are continuously stiffened by roof folded plates is elucidated via application of a connection method that ensures joint stiffness between the roof folded plate and the beam while using Japanese and European design codes. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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14 pages, 6215 KiB

Open AccessArticle

Fundamental Properties of Sub-THz Reflected Waves for Water Content Estimation of Reinforced Concrete Structures

by Akio Tanaka, Koji Arita, Chihiro Kobayashi, Tomoya Nishiwaki, Tadao Tanabe and Sho Fujii

Buildings 2024, 14(4), 1076; https://doi.org/10.3390/buildings14041076 - 12 Apr 2024

Cited by 1 | Viewed by 739

Abstract

Water plays a significant role in the deterioration of reinforced concrete buildings; therefore, it is essential to evaluate the water content of the cover concrete. This study explores a novel non-destructive method for assessing the water content using sub-terahertz (sub-THz) waves. Among the [...] Read more.

Water plays a significant role in the deterioration of reinforced concrete buildings; therefore, it is essential to evaluate the water content of the cover concrete. This study explores a novel non-destructive method for assessing the water content using sub-terahertz (sub-THz) waves. Among the four frequencies selected to evaluate the water content, an increase in reflectance was observed as the unit volume water content increased, and smaller data scatter was confirmed as the frequency increased. The derived empirical equation can classify the corrosion risk of the rebar environment based on the water content obtained using reflectance measurements. In other words, it can contribute to the diagnosis of the building integrity associated with rebar corrosion. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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20 pages, 7443 KiB

Open AccessArticle

Study on the Mechanical Properties and Design Method of Frame-Unit Bamboo Culm Members Based on Semi-Rigid Joints

by Guojin Wang, Xin Zhuo, Shenbin Zhang and Jie Wu

Buildings 2024, 14(4), 991; https://doi.org/10.3390/buildings14040991 - 3 Apr 2024

Cited by 1 | Viewed by 875

Abstract

The frame-unit bamboo culm structure system offers a novel approach to bamboo structure, combining advantages like reduced construction times and simplified joint designs. Despite its benefits, there is limited research on its mechanical properties and computational methodologies. This study conducted bending performance tests [...] Read more.

The frame-unit bamboo culm structure system offers a novel approach to bamboo structure, combining advantages like reduced construction times and simplified joint designs. Despite its benefits, there is limited research on its mechanical properties and computational methodologies. This study conducted bending performance tests on simply supported frame-unit bamboo culm structures, revealing that the bending stiffness of the structure increases with the number of bolts in the edge joints, though with diminishing efficiency. Based on the experimental observations, a calculation model for this type of structure was established, proposing formulas to describe the stiffness relationships between the corner joints, edge joint, and the overall structure. Numerical simulations calculated the stiffness of the edge joint as a function of the number and placement of bolts, indicating that positioning bolts closer to the outer side enhances edge joint stiffness. By inputting the various rotational stiffness values of corner joints into the simulations and stiffness formulas, consistent total stiffness values were obtained, validating the proposed stiffness relationship formulas. The average stiffness values of the corner joints were derived from these formulas and experimental data, and the rotational stiffness of other types of corner points can also be obtained using this method. Furthermore, a finite element computational method tailored for this structural system was introduced, converting the actual structure into a beam element model for calculation. The equivalent joint forces can be distributed to various components of the actual structure, resulting in the internal force distribution of bamboo culms and bolts in the actual structure, thus achieving the design of the components. The calculated displacement values obtained from this method are close to the displacement values in the experiment, proving the feasibility of this method. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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25 pages, 4728 KiB

Open AccessArticle

Bond-Damaged Prestressed AASHTO Type III Girder-Deck System with Retrofits: Parametric Study

by Haoran Ni and Riyad Aboutaha

Buildings 2024, 14(4), 902; https://doi.org/10.3390/buildings14040902 - 26 Mar 2024

Viewed by 689

Abstract

This research describes an in-depth analysis of the flexural strength of a strengthened AASHTO Type III girder-deck system with debonding-damaged strands based on the finite element software ABAQUS 6.17. To investigate the stand-debonding impact and retrofit, two strengthening techniques by the separate use [...] Read more.

This research describes an in-depth analysis of the flexural strength of a strengthened AASHTO Type III girder-deck system with debonding-damaged strands based on the finite element software ABAQUS 6.17. To investigate the stand-debonding impact and retrofit, two strengthening techniques by the separate use of carbon fiber-reinforced polymer (CFRP) and steel plate (SP) were proposed. A detailed finite element analysis (FEA) model considering strand debonding, material deterioration, and retrofitting systems was developed and verified against relevant experimental data obtained by other researchers. The proposed FEA model and the experimental data were in good agreement. The sensitivity of the numerical model to the mesh size, element type, dilation angle and coefficient of friction was also investigated. Based on the verified FEA model, 156 girder-deck systems were studied, considering the following variables: (1) debonding level, (2) span-to-depth ratio (L/d), (3) strengthening type, and (4) strengthening material amount. The results indicated that the debonding level and span-to-depth ratio had a major effect on both load–deflection behaviors and the ultimate strength. The relationships between the enhancement of the ultimate strength and the thickness of the strengthening material were obtained through regression equations with respect to the CFRP- and SP-strengthened specimens. The coefficient of determination (R²) was 0.9928 for the CFRP group and 0.9968 for the SP group. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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16 pages, 7699 KiB

Open AccessArticle

Systematic Calculation of Yield and Failure Curvatures of Reinforced Concrete Cross-Sections

by John Bellos and Apostolos Konstantinidis

Buildings 2024, 14(3), 826; https://doi.org/10.3390/buildings14030826 - 19 Mar 2024

Viewed by 1838

Abstract

This paper examines and provides a robust solution to the problem of yield and failure curvatures of reinforced concrete (RC) cross-sections, taking into account cracking. At the same time, it calculates the corresponding necessary reinforcement or the moment of resistance in both yield [...] Read more.

This paper examines and provides a robust solution to the problem of yield and failure curvatures of reinforced concrete (RC) cross-sections, taking into account cracking. At the same time, it calculates the corresponding necessary reinforcement or the moment of resistance in both yield and failure limit states. Computationally, the problem of determining the actual curvatures is reduced to the bending design problem of the cross-section in the yield and failure limit states. This study shows the researcher and the designer how to systematically calculate the strains for different concrete and steel grades and for standard or random cross-sections. This complex process is quite necessary to determine the respective curvatures. The main concept is presented with an emphasis on the “solution regions” as well as the critical cases of the “asymptotic regions”, both in yield and failure limit states. Our wide-ranging research on RC element design under biaxial bending with axial force for both yield and failure limit states has been completed and validated via sophisticated algorithms and is available for publication. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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19 pages, 8516 KiB

Open AccessArticle

Structural Damage Detection Technique of Secondary Building Components Using Piezoelectric Sensors

by Atsushi Suzuki, Wang Liao, Daiki Shibata, Yuki Yoshino, Yoshihiro Kimura and Nobuhiro Shimoi

Buildings 2023, 13(9), 2368; https://doi.org/10.3390/buildings13092368 - 17 Sep 2023

Cited by 5 | Viewed by 1758

Abstract

With demand for the long-term continued use of existing building facilities, structural health monitoring and damage detection are attracting interest from society. Sensors of various types have been practically applied in the industry to satisfy this need. Among the sensors, piezoelectric sensors are [...] Read more.

With demand for the long-term continued use of existing building facilities, structural health monitoring and damage detection are attracting interest from society. Sensors of various types have been practically applied in the industry to satisfy this need. Among the sensors, piezoelectric sensors are an extremely promising technology by virtue of their cost advantages and durability. Although they have been used in aerospace and civil engineering, their application for building engineering remains limited. Remarkably, recent catastrophic seismic events have further reinforced the necessity of rapid damage detection and quick judgment about the safe use of facilities. Faced with these circumstances, this study was conducted to assess the applicability of piezoelectric sensors to detect damage to building components stemming from concrete cracks and local buckling. Specifically, this study emphasizes structural damage caused by earthquakes. After first applying them to cyclic loading tests to composite beam component specimens and steel frame subassemblies with a folded roof plate, the prospective damage positions were also found using finite element analysis. Crack propagation and buckling locations were predicted adequately. The piezoelectric sensors provided output when the concrete slab showed tensile cracks or when the folded roof plate experienced local buckling. Furthermore, damage expansion and progression were detected multiple times during loading tests. Results showed that the piezoelectric sensors can detect the structural damage of building components, demonstrating their potential for use in inexpensive and stable monitoring systems. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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12 pages, 1810 KiB

Open AccessCase Report

Apparent Influence of Anhydrite in High-Calcium Fly Ash on Compressive Strength of Concrete

by Dinil Pushpalal and Hiroo Kashima

Buildings 2024, 14(9), 2899; https://doi.org/10.3390/buildings14092899 - 13 Sep 2024

Viewed by 554

Abstract

This case study investigates five fly ashes with high CaO and SO₃ levels in their chemical composition and compares the apparent influence of the presence and absence of anhydrite on compressive strength. Another distinguishing feature of the above ashes is that they, [...] Read more.

This case study investigates five fly ashes with high CaO and SO₃ levels in their chemical composition and compares the apparent influence of the presence and absence of anhydrite on compressive strength. Another distinguishing feature of the above ashes is that they, more or less, naturally contain anhydrite. Two different series of mixed proportions were adopted. Series 1 is designed to understand the maximum possible replacement level of fly ash. Series 2 is designed to understand the effect of anhydrite on compressive strength development. The mineral composition and glass phase of fly ashes were determined by X-ray diffraction Rietveld analysis. As a result of this study, we have found that concrete containing anhydrite-rich fly ash exhibits a higher strength than concrete containing anhydrite-free fly ash at all ages. The compressive strength increases with an increasing fly ash replacement ratio when anhydrite-rich ash is used, but strength decreases when the replacement level exceeds a certain point. The optimal amount of anhydrite was 2 ± 0.5 kg/m³ of concrete, excluding the anhydrite contained in cement. Full article

(This article belongs to the Special Issue Advances in Structural and Mechanical Performances of Structures and Materials)

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