Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.78.3.281
Zhengyang Song, H. Konietzky, Xin Cai
{"title":"Modulus degradation of concrete exposed to compressive fatigue loading: Insights from lab testing","authors":"Zhengyang Song, H. Konietzky, Xin Cai","doi":"10.12989/SEM.2021.78.3.281","DOIUrl":"https://doi.org/10.12989/SEM.2021.78.3.281","url":null,"abstract":"","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"78 1","pages":"281"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66125647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.78.4.379
D. Wei
A numerical and computer simulation for dynamic stability analysis of graded porous nanoplates has been provided using a Chebyshev-Ritz-Bolotin approach. The nanoplate has been formulated according to the nonlocal elasticity and a 3-unkown plate model capturing neutral surface location. All of material properties are assumed to be dependent of porosity factor which determines the amount or volume of pores. The nano-size plate has also been assumed to be under temperature and moisture variation. It will be shown that stability boundaries of the nanoplate are dependent on static and dynamical load factors, porosity factor, temperature variation and nonlocal parameter.
{"title":"A numerical and computer simulation for dynamic stability analysis of 3-unknown graded porous nanoplates using a Chebyshev-Ritz-Bolotin method","authors":"D. Wei","doi":"10.12989/SEM.2021.78.4.379","DOIUrl":"https://doi.org/10.12989/SEM.2021.78.4.379","url":null,"abstract":"A numerical and computer simulation for dynamic stability analysis of graded porous nanoplates has been provided using a Chebyshev-Ritz-Bolotin approach. The nanoplate has been formulated according to the nonlocal elasticity and a 3-unkown plate model capturing neutral surface location. All of material properties are assumed to be dependent of porosity factor which determines the amount or volume of pores. The nano-size plate has also been assumed to be under temperature and moisture variation. It will be shown that stability boundaries of the nanoplate are dependent on static and dynamical load factors, porosity factor, temperature variation and nonlocal parameter.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"78 1","pages":"379"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66125740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.78.4.413
W. Guo, Chao-Chin Fan, Yao Cui, Chen Zeng, Li-zhong Jiang, Zhi-wu Yu
Piers are the main lateral force-resisting members of high-speed railway (HSR) bridges used in China and are characterized by low axial load ratios, low longitudinal reinforcement ratios, low stirrup ratios, and high shear span ratios. It is well known that flexural, flexural-shear, and shear failures of piers may occur during an earthquake. In this study, a new shear strength model was developed to simulate the seismic failure of HSR solid piers accurately. First, low cyclic-loading test data of solid piers obtained in recent years were collected to set up a database for model verification. Second, based on the test database, the applicability of existing shear strength models was evaluated. Finally, a new shear strength model for HSR solid piers with round-ended cross-sections was derived based on the truss model and ultimate equilibrium theory. In comparison with existing models, it was demonstrated that the proposed model could be used to predict the shear strength of HSR piers more accurately.
{"title":"Shear strength evaluation of RC solid piers of high-speed railway bridges in China","authors":"W. Guo, Chao-Chin Fan, Yao Cui, Chen Zeng, Li-zhong Jiang, Zhi-wu Yu","doi":"10.12989/SEM.2021.78.4.413","DOIUrl":"https://doi.org/10.12989/SEM.2021.78.4.413","url":null,"abstract":"Piers are the main lateral force-resisting members of high-speed railway (HSR) bridges used in China and are characterized by low axial load ratios, low longitudinal reinforcement ratios, low stirrup ratios, and high shear span ratios. It is well known that flexural, flexural-shear, and shear failures of piers may occur during an earthquake. In this study, a new shear strength model was developed to simulate the seismic failure of HSR solid piers accurately. First, low cyclic-loading test data of solid piers obtained in recent years were collected to set up a database for model verification. Second, based on the test database, the applicability of existing shear strength models was evaluated. Finally, a new shear strength model for HSR solid piers with round-ended cross-sections was derived based on the truss model and ultimate equilibrium theory. In comparison with existing models, it was demonstrated that the proposed model could be used to predict the shear strength of HSR piers more accurately.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"78 1","pages":"413"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66125873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.78.6.691
Ashkan Farazin, M. Mohammadimehr, Amirabbas Ghorbanpour-Arani
In this research, the nanocomposite boxes are simulated using polyurethane (PU) as a thermoplastic polymer with various reinforcements including carbon nanoparticles (CNPs), graphene platelets (GPLs), single-walled carbon nanotubes (SWCNTs), and double-walled carbon nanotubes (DWCNTs), which are as biocompatible and biodegradable. To predict the mechanical and physical properties of each nanocomposite boxes, the molecular dynamics (MDs) method with Materials studio software has been applied. Ultimately, all properties including mechanical and physical properties (Young's modulus, shear modulus, bulk modulus and Poisson's ratio of nanocomposite from CNPs to DWCNTs approximately becomes 5.7, 10.25, 28.63, 96 and 1.39 times, respectively. Then, the stiffness matrix are obtained by Materials studio software. Moreover, the obtained results from this research are validated with the results of the literature. Also, the mechanical and physical properties of nanocomposite are recommended before fabrication. The manufacturing of this nanocomposite is used for biomedical cases such as artificial vessels and piping.
{"title":"Simulation of different carbon structures on significant mechanical and physical properties based on MDs method","authors":"Ashkan Farazin, M. Mohammadimehr, Amirabbas Ghorbanpour-Arani","doi":"10.12989/SEM.2021.78.6.691","DOIUrl":"https://doi.org/10.12989/SEM.2021.78.6.691","url":null,"abstract":"In this research, the nanocomposite boxes are simulated using polyurethane (PU) as a thermoplastic polymer with various reinforcements including carbon nanoparticles (CNPs), graphene platelets (GPLs), single-walled carbon nanotubes (SWCNTs), and double-walled carbon nanotubes (DWCNTs), which are as biocompatible and biodegradable. To predict the mechanical and physical properties of each nanocomposite boxes, the molecular dynamics (MDs) method with Materials studio software has been applied. Ultimately, all properties including mechanical and physical properties (Young's modulus, shear modulus, bulk modulus and Poisson's ratio of nanocomposite from CNPs to DWCNTs approximately becomes 5.7, 10.25, 28.63, 96 and 1.39 times, respectively. Then, the stiffness matrix are obtained by Materials studio software. Moreover, the obtained results from this research are validated with the results of the literature. Also, the mechanical and physical properties of nanocomposite are recommended before fabrication. The manufacturing of this nanocomposite is used for biomedical cases such as artificial vessels and piping.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"78 1","pages":"691-702"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66126412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.2.157
V. Khalafi, J. Fazilati
In the present paper, the free vibration behavior of functionally graded plates containing straight and curved embedded crack is investigated. A NURBS-based multi-patch isogeometric analysis formulation is utilized based on the firstorder shear deformation plate theory. The Nitsche technique is implemented to meet the inter-patch connection constraints. The crack line is assumed as a narrow cut along a straight or free-shape curve path within the plate. The crack growth phenomena are overlooked. The accuracy and quality of the obtained results are compared to those available in the literature. Subsequently, the effect of various material and geometry parameters on the free vibration characteristics of cracked FG plate including the volume-fraction index, crack shape, crack length, crack orientation and, crack location are examined. It learned that the straight crack inclination angle mainly influences the fifth and fourth natural modes. Moreover, the FGM mixture index doesn't noticeably affect the frequency trends. No considerable impact is noted between the edge constraint setups on the fundamental frequency.
{"title":"Free vibration analysis of functionally graded plates containing embedded curved cracks","authors":"V. Khalafi, J. Fazilati","doi":"10.12989/SEM.2021.79.2.157","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.2.157","url":null,"abstract":"In the present paper, the free vibration behavior of functionally graded plates containing straight and curved embedded crack is investigated. A NURBS-based multi-patch isogeometric analysis formulation is utilized based on the firstorder shear deformation plate theory. The Nitsche technique is implemented to meet the inter-patch connection constraints. The crack line is assumed as a narrow cut along a straight or free-shape curve path within the plate. The crack growth phenomena are overlooked. The accuracy and quality of the obtained results are compared to those available in the literature. Subsequently, the effect of various material and geometry parameters on the free vibration characteristics of cracked FG plate including the volume-fraction index, crack shape, crack length, crack orientation and, crack location are examined. It learned that the straight crack inclination angle mainly influences the fifth and fourth natural modes. Moreover, the FGM mixture index doesn't noticeably affect the frequency trends. No considerable impact is noted between the edge constraint setups on the fundamental frequency.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"157"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66127387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.2.169
Amir Pirooznia, A. Moradloo
The purpose of this study is to investigate the size effect, loading rate, and smeared crack models in the nonlinear seismic behavior of concrete arch dams. One of the important parameters in the design of arch concrete dams is the tensile strength of unreinforced mass concrete. Various fracture parameters obtained from experimental results reported for concrete in order to study the size-effect is used in this paper. In the present analysis, the smeared crack method is used in finite element analysis of the Morrow Point arch dam subjected to three components of the TAFT earthquake as a case study. The dependence of fracture, and especially of the size effect, on the loading rate is described. Models incorporating nonlinear analysis in three cases with and without the size effect of dam concrete and fluid-structure interaction are employed to evaluate and compare them. The water is taken as an inviscid, compressible fluid, and the foundation is rigid. From the study, it is concluded that the participation of the size effect leads to higher values of maximum displacements and stresses in benchmark points compared to the model that ignores the size effect. The crack initiation criterion based on the maximum tensile stress according to the size effect of concrete, and also the dynamic loading range should be defined. Results show considering fixed smeared crack models used in the concrete specimen as well as the size effect of concrete materials, will lead to the crack profile is more realistic and will represent near to real behavior of concrete fracture. The results are of significant interest for the concrete fracture of dams; hence the loading rate should be adopted for fracture properties obtained in dams.
{"title":"Seismic fracture analysis of concrete arch dams incorporating the loading rate dependent size effect of concrete","authors":"Amir Pirooznia, A. Moradloo","doi":"10.12989/SEM.2021.79.2.169","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.2.169","url":null,"abstract":"The purpose of this study is to investigate the size effect, loading rate, and smeared crack models in the nonlinear seismic behavior of concrete arch dams. One of the important parameters in the design of arch concrete dams is the tensile strength of unreinforced mass concrete. Various fracture parameters obtained from experimental results reported for concrete in order to study the size-effect is used in this paper. In the present analysis, the smeared crack method is used in finite element analysis of the Morrow Point arch dam subjected to three components of the TAFT earthquake as a case study. The dependence of fracture, and especially of the size effect, on the loading rate is described. Models incorporating nonlinear analysis in three cases with and without the size effect of dam concrete and fluid-structure interaction are employed to evaluate and compare them. The water is taken as an inviscid, compressible fluid, and the foundation is rigid. From the study, it is concluded that the participation of the size effect leads to higher values of maximum displacements and stresses in benchmark points compared to the model that ignores the size effect. The crack initiation criterion based on the maximum tensile stress according to the size effect of concrete, and also the dynamic loading range should be defined. Results show considering fixed smeared crack models used in the concrete specimen as well as the size effect of concrete materials, will lead to the crack profile is more realistic and will represent near to real behavior of concrete fracture. The results are of significant interest for the concrete fracture of dams; hence the loading rate should be adopted for fracture properties obtained in dams.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"169"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66127733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.2.237
Huayong Lv, Zhanbo Cheng, Yaqing Dong, Jing Zhang, Y. Ma
There is normally the occurrence of pre-existing cracks and holes in coal mass to influence its mechanical behaviours. And the crack initiation and propagation around the tip of pre-existing cracks can be observed to induce the overall failure of coal mass finally. In this study, two groups of hole with the radius of 10 mm connecting one crack with length and width of 20 mm and 1 mm, respectively, were pre-existed in sample to explore the influence of crack angle (from 0 to 90o) on the unconfined compressive strength (UCS), crack initiation and propagation, and failure modes of coal mass with combined faults by using RFPA2D. The results showed that the stress-strain curves of specimen with double-hole-crack exhibit multiple stress drop compared to that of intact coal sample, especially in the post-peak stage. Moreover, UCS decreased firstly with the crack angle increasing to 30o and then increased until the crack angle reaching to 75o following by decreasing with the continuous increase of crack angle to 90o. In addition, the failure mode of double-hole-crack specimen with the crack angle of 0-30o can be regards as the dominated tensile failure combined with shear failure, which was consist with the failure pattern of intact specimen. On the other hand, the failure mode of double-hole-crack specimen with the crack angle of 45-90o is the dominated shear failure combined with tensile failure. Meanwhile, the distribution characteristics of acoustic emission energy can be used to better reflect the deformation and failure process of coal mass with combined defects.
{"title":"Numerical simulation on the crack initiation and propagation of coal with combined defects","authors":"Huayong Lv, Zhanbo Cheng, Yaqing Dong, Jing Zhang, Y. Ma","doi":"10.12989/SEM.2021.79.2.237","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.2.237","url":null,"abstract":"There is normally the occurrence of pre-existing cracks and holes in coal mass to influence its mechanical behaviours. And the crack initiation and propagation around the tip of pre-existing cracks can be observed to induce the overall failure of coal mass finally. In this study, two groups of hole with the radius of 10 mm connecting one crack with length and width of 20 mm and 1 mm, respectively, were pre-existed in sample to explore the influence of crack angle (from 0 to 90o) on the unconfined compressive strength (UCS), crack initiation and propagation, and failure modes of coal mass with combined faults by using RFPA2D. The results showed that the stress-strain curves of specimen with double-hole-crack exhibit multiple stress drop compared to that of intact coal sample, especially in the post-peak stage. Moreover, UCS decreased firstly with the crack angle increasing to 30o and then increased until the crack angle reaching to 75o following by decreasing with the continuous increase of crack angle to 90o. In addition, the failure mode of double-hole-crack specimen with the crack angle of 0-30o can be regards as the dominated tensile failure combined with shear failure, which was consist with the failure pattern of intact specimen. On the other hand, the failure mode of double-hole-crack specimen with the crack angle of 45-90o is the dominated shear failure combined with tensile failure. Meanwhile, the distribution characteristics of acoustic emission energy can be used to better reflect the deformation and failure process of coal mass with combined defects.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"237"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66128086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.2.247
A. Mortazavi
The current investigation deals with assessing the search performance of a recently developed, parameter-free, and self-adaptive search algorithm so-called Interactive Fuzzy Search Algorithm (IFSA) in solving weight minimization of the constrained structural optimization problems with discrete variables. The proposed IFSA combines the navigation pattern of the Interactive Search Algorithm (ISA) with the decision-making competence of fuzzy reasoning. The fuzzy module of the proposed IFSA permanently monitors the search process and adjusts each agent's search behavior by considering the governing condition of the current problem. In structural optimization, due to construction limitations, it is more realistic to select the sizing variables from a discrete domain. Thus, in this study, to empirically evaluate the search capability of the IFSA, it is applied to solve a suite of structural optimization problems with the discrete design variables. The attained outcomes are compared with the ISA and some other related methods addressed in the relevant literature. The acquired accuracy level and demanded number of objective function evaluations indicates that the IFSA, comparatively, using lower computational cost could found lighter structural systems. Also, the comparison of the attained standard deviation values shows that the IFSA demonstrates higher stability during the optimization process. These superior outcomes designate that the fuzzy decision-making mechanism of the IFSA could work properly in dynamically adapting the search behavior of the algorithm with the governing condition of the current problem. Consequently, the promising gained results reveal that IFSA can effectively be applied in solving the structural optimization problems with discrete search domains.
{"title":"Solving structural optimization problems with discrete variables using interactive fuzzy search algorithm","authors":"A. Mortazavi","doi":"10.12989/SEM.2021.79.2.247","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.2.247","url":null,"abstract":"The current investigation deals with assessing the search performance of a recently developed, parameter-free, and self-adaptive search algorithm so-called Interactive Fuzzy Search Algorithm (IFSA) in solving weight minimization of the constrained structural optimization problems with discrete variables. The proposed IFSA combines the navigation pattern of the Interactive Search Algorithm (ISA) with the decision-making competence of fuzzy reasoning. The fuzzy module of the proposed IFSA permanently monitors the search process and adjusts each agent's search behavior by considering the governing condition of the current problem. In structural optimization, due to construction limitations, it is more realistic to select the sizing variables from a discrete domain. Thus, in this study, to empirically evaluate the search capability of the IFSA, it is applied to solve a suite of structural optimization problems with the discrete design variables. The attained outcomes are compared with the ISA and some other related methods addressed in the relevant literature. The acquired accuracy level and demanded number of objective function evaluations indicates that the IFSA, comparatively, using lower computational cost could found lighter structural systems. Also, the comparison of the attained standard deviation values shows that the IFSA demonstrates higher stability during the optimization process. These superior outcomes designate that the fuzzy decision-making mechanism of the IFSA could work properly in dynamically adapting the search behavior of the algorithm with the governing condition of the current problem. Consequently, the promising gained results reveal that IFSA can effectively be applied in solving the structural optimization problems with discrete search domains.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"247"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66128094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.79.3.327
P. Ni, Xiaojuan Wang, Hongyuan Zhou
Most of the existing output-only damage detection methods require the number of sensors should be larger than the number of unknown excitation force, and the force location should be available. This paper presents a novel output-only damage detection method without these requirements. The proposed method is based on the correlation function of acceleration responses. When the structure is under white noise excitations (or ambient excitations), the correlation function of acceleration responses can be treated as free vibration responses with unknown initial conditions. The unknown structural parameters and initial conditions can be simultaneously identified by minimizing the difference between the measured and calculated correlation functions. The unknown initial conditions are identified with state space method and the unknown structural parameters are updated with sensitivity method. Numerical studies of a 2D truss and a five-bay 3D frame structure are conducted to demonstrate the accuracy, effectiveness, and robustness of the proposed method. Experimental studies on an eight-floor steel frame are further carried out. Results show that the proposed method is not only insensitive to environmental noise but also applicable when the number of sensors is less than that of unknown excitations. Also, the proposed method can be used for damage detection when the force location is unknown.
{"title":"Output-only structural damage detection under multipleunknown white noise excitations","authors":"P. Ni, Xiaojuan Wang, Hongyuan Zhou","doi":"10.12989/SEM.2021.79.3.327","DOIUrl":"https://doi.org/10.12989/SEM.2021.79.3.327","url":null,"abstract":"Most of the existing output-only damage detection methods require the number of sensors should be larger than the number of unknown excitation force, and the force location should be available. This paper presents a novel output-only damage detection method without these requirements. The proposed method is based on the correlation function of acceleration responses. When the structure is under white noise excitations (or ambient excitations), the correlation function of acceleration responses can be treated as free vibration responses with unknown initial conditions. The unknown structural parameters and initial conditions can be simultaneously identified by minimizing the difference between the measured and calculated correlation functions. The unknown initial conditions are identified with state space method and the unknown structural parameters are updated with sensitivity method. Numerical studies of a 2D truss and a five-bay 3D frame structure are conducted to demonstrate the accuracy, effectiveness, and robustness of the proposed method. Experimental studies on an eight-floor steel frame are further carried out. Results show that the proposed method is not only insensitive to environmental noise but also applicable when the number of sensors is less than that of unknown excitations. Also, the proposed method can be used for damage detection when the force location is unknown.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"79 1","pages":"327"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66128486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SEM.2021.80.1.047
Oday Z. Jaradat, Karima Gadri, B. Tayeh, Abdelhamid Guettalaa
This experimental study aims to investigate the properties of sand concrete (SC) by using sisal fibres and latex in various fields in construction. Sisal fibres were applied at four ratios of 0.05%, 0.10%, 0.15% and 0.20%, while liquid latex was replaced with three ratios of 15%, 25% and 35%. In this context, ideal percentages of sisal fibre (0.1% F) and latex (35% L) were combined in a single cement matrix. For each percentage, tests on flow, density, compressive strength, flexural strength, ultrasonic pulse velocity, modulus of elasticity, water accessible porosity, water absorption and shrinkage were performed on fresh and hardened SC. Scanning electron microscopy (SEM) was also conducted for microstructure analysis. Results indicate that adding latex emulsion to SC containing sisal fibres increased the adhesion of the fibres to the cement matrix, which contributed to the increase in flexural strength and the decrease in shrinkage. This condition also helped reduce the porosity and water absorption of latex-modified SC with sisal fibres compared with SC that contained fibres. The improvement occurred in the properties that constitute an obstacle to the widespread use of SC. Thus this improvement has practical implications.
{"title":"Influence of sisal fibres and rubber latex on the engineering properties of sand concrete","authors":"Oday Z. Jaradat, Karima Gadri, B. Tayeh, Abdelhamid Guettalaa","doi":"10.12989/SEM.2021.80.1.047","DOIUrl":"https://doi.org/10.12989/SEM.2021.80.1.047","url":null,"abstract":"This experimental study aims to investigate the properties of sand concrete (SC) by using sisal fibres and latex in various fields in construction. Sisal fibres were applied at four ratios of 0.05%, 0.10%, 0.15% and 0.20%, while liquid latex was replaced with three ratios of 15%, 25% and 35%. In this context, ideal percentages of sisal fibre (0.1% F) and latex (35% L) were combined in a single cement matrix. For each percentage, tests on flow, density, compressive strength, flexural strength, ultrasonic pulse velocity, modulus of elasticity, water accessible porosity, water absorption and shrinkage were performed on fresh and hardened SC. Scanning electron microscopy (SEM) was also conducted for microstructure analysis. Results indicate that adding latex emulsion to SC containing sisal fibres increased the adhesion of the fibres to the cement matrix, which contributed to the increase in flexural strength and the decrease in shrinkage. This condition also helped reduce the porosity and water absorption of latex-modified SC with sisal fibres compared with SC that contained fibres. The improvement occurred in the properties that constitute an obstacle to the widespread use of SC. Thus this improvement has practical implications.","PeriodicalId":51181,"journal":{"name":"Structural Engineering and Mechanics","volume":"80 1","pages":"47"},"PeriodicalIF":2.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66130768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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