Case Studies in Construction Materials最新文献

{"title":"Experimental research on the mechanical properties of alkali-resistant glass fiber concrete acting as tunnel seismic isolation layer under periodic cyclic dynamic loading","authors":"Cong Zhang ,&nbsp;Qingbiao Wang ,&nbsp;Yonggang Zhang ,&nbsp;Shanyong Wang ,&nbsp;Xinru Zhang ,&nbsp;Yunxiao Wang","doi":"10.1016/j.cscm.2024.e03446","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03446","url":null,"abstract":"<div><p>The installation of seismic isolation layer is an effective measure to ensure the safe operation of underground projects such as tunnels during extreme seismic activities. Material parameters, mechanical properties, and design patterns of the seismic isolation layer are key research topics in exploring effective reduction of seismic response. This study mainly focused on the dynamic performance of the seismic isolation layer in tunnels. A series of drop hammer impact tests and laboratory shaking table tests were performed to reveal the seismic features of the seismic isolation layer under periodic external loading. The test results indicated that all cracks in the specimen initiated from the center and dispersed outwards under the cycle impact of the drop hammer. The incorporation of alkali-resistant glass fibers in concrete (AR-GFRC) effectively provided \"reinforcement \" and \"crack resistance\" under cyclic loading of the drop hammer, and the minimum number and width of cracks were observed at a 0.75 % HD fiber content and a 0.5 % HP fiber content. In the x- and y-axis directions, the seismic isolation layer effectively mitigated peak acceleration, strain response, and displacement at the tunnel vault and invert, but significant nonlinearity was identified. When the thickness of seismic isolation layer was 10 mm, the peak seismic response of the lining were minimum at a 0.75 % HD fiber content and a 0.5 % HP fiber content. However, the thickness of the lining was not directly related to the destruction of the lining. The tunnel mainly experienced shear deformation in the x-axis direction, with significant deformations from the left arch waist to the right arch foot (45°-225°), resulting in transverse cracking. The tunnel primarily underwent tensile and compressive deformation in the y-axis direction, with significant deformations occurring in the inverted vault (0°-180°), resulting in tension and circumferential cracks. This research can provide valuable data support and reference for the design and construction of underground projects such as tunnels.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03446"},"PeriodicalIF":6.5,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524005977/pdfft?md5=8f78666ea79e0d89a23b7f08c4b72938&pid=1-s2.0-S2214509524005977-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141595070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and numerical investigation on fire performance of hollow-cavity ceramsite concrete wall-panel","authors":"Anlian Wang ,&nbsp;Zhiwen Zhang ,&nbsp;Zeqing Wan ,&nbsp;Yan Liu","doi":"10.1016/j.cscm.2024.e03492","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03492","url":null,"abstract":"<div><p>To investigate the fire performance of hollow-cavity ceramsite concrete wall-panels (HCCCW), this study conducted one-sided fire tests on four HCCCWs. The experiment yielded results on their thermal response, fire resistance, and out-of-plane deformation, providing insights into the heat transfer mechanism of HCCCWs under one-sided fire exposure. An analysis of the distribution characteristics of section temperature fields and temperature gradients was performed by establishing finite element (FE) models. Based on the validated models, parametric studies were conducted on hollow-cavity area, volume-cavity ratio, ceramsite concrete density, and type of filling material. The results indicate that as the volume-cavity ratio increased from 23.55 % to 35.00 %, the duration of steam escape from the unexposed surface decreased by 43.75 % and the number of cracks on the fire-exposed surface decreased by 58.97 %. In the temperature-time curve for the unexposed surface of HCCCW, both the duration of heat front propagation and temperature plateau increase with a decrease in volumetric cavity ratio and cavity surface area. Compared to heat conduction in ceramsite concrete, cavity radiation significantly improves heat transfer efficiency. Additionally, the temperature at the center of the cavity is approximately 20 % higher than at its midpoint along with webbing. Decreasing hollow-cavity area and volume-cavity ratio or increasing ceramsite concrete density effectively enhances HCCCW's fire resistance. Considering structural weight, material cost, and fire resistance, filling cavities with rockwool proves to be most cost-effective.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03492"},"PeriodicalIF":6.5,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006430/pdfft?md5=97534b96282110e342aaa92e457b1824&pid=1-s2.0-S2214509524006430-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141593512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental research on the post-fire semi-rigid behavior of the glulam bolted joints with slotted-in steel plates","authors":"Weibin Ni ,&nbsp;Xuan Wang ,&nbsp;Ronghui Zhang ,&nbsp;Yongwang Zhang ,&nbsp;Qiuyue Wu ,&nbsp;Yanyan Sun ,&nbsp;Lu Wang","doi":"10.1016/j.cscm.2024.e03488","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03488","url":null,"abstract":"<div><p>This paper conducted series fire tests without load for glulam bolted joints with slotted-in steel plates, where the effects of fire exposure time, fire-retardant coating, fire exposure side and connecting steel bolts number for specimens were considered. Meanwhile, after fire tests, post-fire-performance (PFP) tests were conducted to explore and compare the residual load-carrying capacity and post-fire semi-rigid behavior of the glulam bolted joints with slotted-in steel plates. As a benchmark and comparison, two specimens were also conducted for bending tests without fire exposure. The test results showed that the steel inside the joints including steel box, slotted-in steel plate and steel bolts had a significant effect on the internal temperature distributions and the charring of outer timber. Moreover, the post-fire strength and ductility of the tested specimens decreased with the increase of the fire exposure time, while painting with fire-retardant coating, reducing fire exposure sides and increasing connecting steel bolts for specimens could appropriately increase their residual bending resistance and ductility deformation capacity. Finally, considering the different residual sections for timber after charring under different fire exposure times, a semi-rigid numerical model for the prediction of moment-rotation of the joints after fire exposure was established for the glulam bolted joints with slotted-in steel plates, and the numerical results demonstrated that the predicted moment-rotation curves were in good agreement with the tested curves. The test results could provide a reference for the performance-based fire protection design for timber structures.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03488"},"PeriodicalIF":6.5,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006399/pdfft?md5=19da7eb2c986cb69906136fa65bd654c&pid=1-s2.0-S2214509524006399-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141543249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of steel protective structure for historical masonry aqueducts against rockfall: Numerical and field studies","authors":"Suleyman Istemihan Cosgun ,&nbsp;Mohammad Manzoor Nasery","doi":"10.1016/j.cscm.2024.e03477","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03477","url":null,"abstract":"<div><p>This study investigates the design and impact performance of novel steel protection system intended to safeguard historical masonry aqueducts from damage caused by hazardous rocks. The historical aqueduct under consideration is located on the Sumela Monastery campus. To achieve this, we developed a three-dimensional (3D) photogrammetric model of the study area and identified all risky blocks along with their real positions. Subsequently, we conducted 3200 probabilistic rockfall analyses in eight critical trajectories with four different rock sizes to calculate the velocity, kinetic energy, and run-out distance of fallen blocks. In the second part of the study, finite element models of the steel protective structure were created using Abaqus software. A nonlinear dynamic impact analysis method was applied to analyze nine rockfall scenarios with two different geometries and four different sizes. Based on the rockfall and impact analyses, sections of the protection structure were designed using plastic design criteria. The steel protection structure for aqueducts demonstrated high effectiveness against rockfall, with a risk index (I_r) ranging from 0.93 to 1.00 (except for the upper end of the column–beam connection impacts). Even in these scenarios, the structure provided protection by reducing rock energy and altering its trajectory. In the third part, a steel structure was constructed in the field, and a rock cleaning process was carried out. During rock cleaning, punctures occurred while breaking sharp rocks. To mitigate this risk, a parametric study was conducted using a steel angle stopper. The proposed simple steel angle stopper effectively reduced rockfall damage to historical structures by blocking rock passages and rapidly reducing kinetic energy. Ultimately, during the removal of 5000 m³ of hazardous rocks, no damage was inflicted on the historical structure. The protection system showed a near 100 % success rate in safeguarding the aqueduct. This temporary structure can be employed to protect historical structures from rockfall hazards.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03477"},"PeriodicalIF":6.5,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006284/pdfft?md5=cca84d590c81ccaa368977511a649d9b&pid=1-s2.0-S2214509524006284-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141592862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the design method of multi-component industrial solid waste low carbon cementitious material with cement as the activator","authors":"Ruiqi Wang ,&nbsp;Guodong Li ,&nbsp;Changyan Li ,&nbsp;Yupeng Huo ,&nbsp;Teng Wang ,&nbsp;Peng Hou ,&nbsp;Zuo Gong","doi":"10.1016/j.cscm.2024.e03478","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03478","url":null,"abstract":"<div><p>The relationship between microstructure and mechanical properties of multi-component solid waste low-carbon cementitious materials has been widely pay attention to. However, industrial solid waste is a complex multi-component system with many variable factors, which makes it difficult to design the formulation of cementitious materials. This paper pioneered the application of machine learning (ML) models, algorithms and error rates to analyze the compressive and flexural strength of fly ash-based pastes. Coefficient of determination (<em>R</em>^<em>2</em>), mean squared error (<em>MSE</em>), root mean square error (<em>RMSE</em>), mean absolute error (<em>MAE</em>) and a20-index were used to evaluate robustness. X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Taylor (BET) were carried out to analyze evolution of cementitious materials. The evaluation results of ML models exhibited that the Gradient boosting regression (GBR) model had the best determination parameters and a steep normal distribution fitting curve with an a20-index of 0.861. GBR model exhibited the best robustness. The key factors of fly ash-based cementitious materials were identified by Pearson's coefficient, which was benefit to determine the formulation of multi-component solid waste low-carbon cementitious materials. Furthermore, experiments also demonstrated that the optimum ratio of multi-component solid waste low carbon cementitious material was 10 % gypsum, 10 % metakaolin, 45 % fly ash, 15 % slag and 20 % cement, respectively. It was worth noting that the compressive strength of this kind of multi-component solid waste low-carbon cementitious materials reached 35 MPa, which was superior to the mechanical properties of P·O 32.5 cement. The results of phase, SEM images and pore structure distribution showed that the synergistic effect of the multi-component solid waste materials effectively filled the material voids and also facilitated the formation of a variety of gelatinous materials through gelling reactions in the late stage (14–28 d). This work will promote the resource utilization of industrial solid waste, contribute to carbon reduction, and can accelerate the green revolution of concrete.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03478"},"PeriodicalIF":6.5,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006296/pdfft?md5=2ab96a9d42555453a5fc43be20393c7b&pid=1-s2.0-S2214509524006296-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141593511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strength prediction of asphalt mixture under interactive conditions based on BPNN and SVM","authors":"Xiyan Fan ,&nbsp;Songtao Lv ,&nbsp;Chengdong Xia ,&nbsp;Dongdong Ge ,&nbsp;Chaochao Liu ,&nbsp;Weiwei Lu","doi":"10.1016/j.cscm.2024.e03489","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03489","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Predicting the strength of asphalt mixtures with different specifications under various conditions was a highly challenging task. The standard strength test lacked consideration of multiple factors, resulting in an inability to accurately characterize the properties of the pavement. This paper proposed a strength prediction approach based on influence factor analysis using the back-propagation neural network (BPNN) and support vector machine (SVM). The strength dataset was processed to realize the physical analysis of factors influencing asphalt mixture strength. Stress state (Direct tensile with&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;250&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, Uniaxial compression with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mi&gt;Φ&lt;/mi&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, Indirect tensile with&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;63.5&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mi&gt;Φ&lt;/mi&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;,Four-point bending with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;380&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;63.5&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), temperatures (35 ̊C, 25 ̊C, 15 ̊C, 0 ̊C, −15 ̊C, −25 ̊C), and load rates (0.02 MPa/s, 0.05 MPa/s, 0.1 MPa/s, 0.5 MPa/s) were selected as input features to train the BPNN and SVM. The strength prediction model for asphalt mixture under complex conditions was established by optimizing the parameters of algorithms. The performance of the BPNN and SVM was evaluated and compared by the root mean square error, determination coefficient, and mean absolute percentage deviation. The results show that the asphalt mixture specimen with different specifications under various stress states presents significant discrepancies. The maximum compressive strength is followed by the bending strength, then comes the indirect tensile strength, and the smallest is the direct tensile strength. The difference in the role of asphalt or aggregate is the main reason for the diversity in strength. The increase in temperature leads to asphalt softening, which reduces the strength of the asphalt mixture. The increased loading rate meant the loading time was short cause the strength increased. In addition, the predictive value of the strength under various conditions was consistent with the results of the experiments. The hidden neurons in the BPNN were set to 9, achieving the prediction accuracy is high (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0.99&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;). The penalty coefficient of the SVM was set to 500 and the kernel function parameter was set to 300, resulting in the error within 0.02 %. When comparing the performance metrics of BPNN and SVM, it becomes evident that SVM outperforms BPNN in terms of prediction accuracy. Specifically, SVM exhibits a coefficient of determination of 0.9983, a root m","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03489"},"PeriodicalIF":6.5,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006405/pdfft?md5=9c4aa13d97178342c754b5202e0dca87&pid=1-s2.0-S2214509524006405-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141595054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental analysis of the impact of alternating magnetic fields on the compressive strength of concrete with various silica sand and microsilica compositions","authors":"Mohammad Mahdi Amini,&nbsp;Morteza Ghanepour,&nbsp;Omid Rezaifar","doi":"10.1016/j.cscm.2024.e03487","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03487","url":null,"abstract":"<div><p>This research experimentally assessed the compressive strength enhancement of 7- and 28-day concrete specimens with up to 20 % silica sand and micro silica under an alternating magnetic field up to 1 Tesla. By applying magnetic fields to hardened concrete, properties can be tailored to specific needs, thus lowering cement usage and CO2 production. It was found that adding 10 % micro silica reduced the compressive strength at 7 and 28 days, while using 10 % silica sand and 5 % micro silica increased the compressive strength by 14.55 % and 7.79 %, respectively. Exposing specimens to a magnetic field increased compressive strength, with improvements up to 60.36 % for 7-day and 48.02 % for 28-day concrete at 1 T. Incorporating silica sand and micro silica in concrete positively impacts compressive strength under a magnetic field. Silica sand enhances compatibility with additives, improving strength. However, substituting 10 % of cement with micro silica reduces strength due to decreased aggregate adherence. 7-day specimens are more susceptible to magnetic fields than 28-day specimens due to lower displacement in younger samples. This innovative method enables controlled material behavior under magnetic influence. It aims to reduce cement usage while compensating for strength reduction caused by micro silica substitution. The study also determines the minimum magnetic field needed to counteract strength decrease; the aspects which not previously explored.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03487"},"PeriodicalIF":6.5,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006387/pdfft?md5=3ec8ce4f479672baebea0b0f43c70cc2&pid=1-s2.0-S2214509524006387-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141543254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of alkaline rice straw fibers content and curing ages on static mechanical properties of cemented lithium mica tailings backfill","authors":"Hongke Pan ,&nbsp;Quanmao Xiao ,&nbsp;Nanhui Huang ,&nbsp;An Xiao ,&nbsp;Daopei Zhu","doi":"10.1016/j.cscm.2024.e03450","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03450","url":null,"abstract":"<div><p>Alkaline rice straw fibers (ARSF), as a widely available and recyclable plant fiber source, can provide new insights for improving the mechanical properties of backfill and the treatment of agricultural waste resources research. Different amounts of ARSF were prepared to enhance the cemented lithium mica tailings backfill (CLMTB), and uniaxial compression strength (UCS) tests and Brazilian splitting tensile strength tests were conducted to study the influence of ARSF on the static mechanical properties of CLMTB samples. Firstly, the flowability of mortars with different ARSF content was tested, the results showed that the flowability decreased by a maximum of 5.4 %, which met the construction requirements of cement mortar in the construction process. The UCS showed an increasing trend and then reduced with the increased ARSF content, with 0.15 % being the optimal content, showing a maximum increase of 14.2 %. Under Brazilian splitting loading conditions, the tensile strength gradually increased with the increased ARSF content, with 0.60 % being the optimal content. The UCS of the CLMTB samples showed exponential growth with increased curing age. Additionally, there was a linear functional relationship between the curing age and the tensile strength of the CLMTB samples. The experimental results indicate that the ARSF improved the toughness and changed the failure mode of the CLMTB samples. In the meantime, it increased the residual bearing capacity and the peak tensile strain of the CLMTB samples.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03450"},"PeriodicalIF":6.5,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006016/pdfft?md5=a6bcde968c1ccc068ab57d1903073f33&pid=1-s2.0-S2214509524006016-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141541746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on shear failure characteristics of fiber-reinforced shotcrete-granite interface based on surface scanning","authors":"Zhongjing Hu ,&nbsp;Qingbiao Wang ,&nbsp;Yiming Ma ,&nbsp;Hao Lv ,&nbsp;Weizhen Liu ,&nbsp;Ran Yan ,&nbsp;Keyong Wang ,&nbsp;Tangsha Shao ,&nbsp;Yong Sun","doi":"10.1016/j.cscm.2024.e03486","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03486","url":null,"abstract":"<div><p>The shear characteristics of the concrete-rock interface play a crucial role in the stability of engineering structures in geotechnical construction. This study utilized a combination of three-dimensional scanning and sculpting techniques to create fiber-reinforced shotcrete-granite combination specimens. Specimens with varying interface roughness were tested in direct shear under different normal stress conditions. A method for analyzing the shear failure characteristics of granite interfaces using the XTOM industrial optical surface scanning system is proposed. Furthermore, an enhanced formula for estimating the peak shear strength of the interface in fiber-reinforced concrete-rock composite specimens is introduced. The research findings suggest the following: (1) The shear strength of the fiber shotcrete-granite interface is significantly increased by normal stress. Specifically, under joint roughness coefficient (JRC) 2.0 conditions, the shear strength at a normal stress of 2.0 MPa is 185.89 % higher than at 0.5 MPa. (2) A method for analyzing the damage characteristics of rough interfaces using surface scanning technology is introduced. Utilizing surface scanning technology, the rough surface is reconstructed both before and after damage, allowing for the extraction of a two-dimensional roughness curve that effectively captures the influence of normal stress and roughness on interface shear failure characteristics. (3) Based on the observed macroscopic and microscopic damage characteristics, as well as the scanning electron microscope (SEM) morphology of the interface after shearing, it is evident that shearing damage predominantly occurs on the side of the fiber-reinforced concrete. Furthermore, it was found that the degree of damage on the concrete side increases with higher roughness and normal stress levels, while the interface shear strength is enhanced by the presence of alkali-resistant glass fiber (ARGF). (4) The calculation formula of concrete-rock interface shear strength was improved, and its accuracy was verified through experiments. The research findings can serve as a data foundation and theoretical support for studying the shear characteristics of fiber-reinforced concrete-rock interfaces and geotechnical engineering construction.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03486"},"PeriodicalIF":6.5,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006375/pdfft?md5=27d20e12937f4b32b17fee0005ad33d7&pid=1-s2.0-S2214509524006375-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141543252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of post-processing methods on bond-slip behavior of nonlinear Fe-SMA lap-shear joints","authors":"Lingzhen Li ,&nbsp;Enzo Martinelli ,&nbsp;Wandong Wang ,&nbsp;Eleni Chatzi ,&nbsp;Elyas Ghafoori","doi":"10.1016/j.cscm.2024.e03485","DOIUrl":"https://doi.org/10.1016/j.cscm.2024.e03485","url":null,"abstract":"<div><p>Prestressed bonded strengthening for structures employing iron-based shape memory alloy (Fe-SMA) has been proven promising. Analyzing adhesively bonded joints necessitates a thorough understanding of the bond-slip behavior. However, when examining the bond-slip behavior of Fe-SMA-to-steel joints comprising nonlinear adhesives, the “forward” and “backward” post-processing methods, representing the current state-of-the-art, produce a trilinear and a trapezoidal bond-slip pattern, respectively, which is inconsistent. To address this inconsistency, the current study investigates the bond behavior of Fe-SMA-to-steel joints, with a particular focus on the bond-slip behavior. Two finite element (FE) joints, one featuring a linear adhesive and the other comprising a nonlinear adhesive, are modeled and compared against physical tests from literature. The “forward” and “backward” processing methods are used to analyze the bond behavior of the two FE joints. Eventually, the aforementioned inconsistency is resolved; a triangular and a trapezoidal bond-slip pattern are characterized for Fe-SMA-to-steel lap-shear joints with linear and nonlinear adhesives, respectively. The trilinear bond-slip behavior is concluded as a result of error accumulation and propagation during the “forward” processing. A hybrid post-processing method, which takes the advantages of both the “forward” and “backward” processing methods, is further proposed for inferring the full-range behavior; the resulting experimental behaviors closely align with simulations using a trapezoidal bond-slip model as input. A comparison against carbon fiber reinforced polymer (CFRP) lap-shear joints demonstrates similar bond-slip characteristics between Fe-SMA and CFRP lap-shear joints.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"21 ","pages":"Article e03485"},"PeriodicalIF":6.5,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006363/pdfft?md5=1d291a6ce7e268f83593b712300b10d8&pid=1-s2.0-S2214509524006363-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141543253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}