Abstract
This study examined the changes in the mechanical properties of coral concrete under different coconut fiber admixtures. To accomplish this goal, the compressive strength, splitting tensile strength, flexural strength and elastic modulus properties of coral concrete blocks reinforced with coconut fibers were measured. The results showed that the addition of coconut fiber had little effect on the cube and axial compressive strengths. With increasing coconut fiber content, the flexural strength and splitting tensile strength of the concrete changed substantially, first by increasing and then by decreasing, with maximum increases of 36.0% and 12.8%, respectively; additionally, the addition of coconut fibers resulted in a failure type with some ductility. When the coconut fiber-reinforced coral concrete was 7 days old, it reached approximately 74% of its maximum strength. The addition of coconut fiber did not affect the early strength of the coral concrete mixed with seawater. When the amount of coconut fiber was no more than 3 kg/m3, the resulting concrete elastic modulus decreased only slightly from that of a similar concrete without coconut fiber, and the maximum decrease was 5.4%. The optimal dose of coconut fiber was 3 kg/m3 in this study.
Key Words
coconut fiber; concrete; coral; elastic modulus; mechanical properties
Address
Cunpeng Liu: School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia; Department of Civil and Surveying Engineering, Guilin University of Technology at Nanning, Nanning, Guangxi Zhuang, China
Fatimah De'nan: School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia
Qian Mo: Department of Civil and Architectural Engineering, Guangxi Transport Vocational and Technical College, Nanning, Guangxi Zhuang, China
Yi Xiao: School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia
Yanwen Wang: Department of Civil and Architectural Engineering, Guangxi Transport Vocational and Technical College, Nanning, Guangxi Zhuang, China
Abstract
This article presents the behaviour and design of cold-formed steel (CFS) web-stiffened lipped channel beams that
primarily fail owing to the buckling interaction of distortional and global buckling modes. The incorporation of an intermediate stiffener in the web of the lipped channel improved the buckling performance leads to distortional buckling at intermediate length beams. The prediction of the strength of members that fail in individual buckling modes can be easily determined using the current DSM equations. However, it is difficult to estimate the strength of members undergoing buckling interactions. Special attention is required to predict the strength of the members undergoing strong buckling interactions. In the present study,
the geometric dimensions of the web stiffened lipped channel beam sections were chosen such that they have almost equal
distortional and global buckling stresses to have strong interactions. A validated numerical model was used to perform a parametric study and obtain design strength data for CFS web-stiffened lipped channel beams. Based on the obtained numerical data, an assessment of the current DSM equations and the equations proposed in the literature (for lipped channel CFS sections) is performed. Suitable modifications were also proposed in this work, which resulted in a higher level of design accuracy to predict the flexural strength of CFS web stiffened lipped channel beams undergoing distortional and global mode interaction.
Furthermore, reliability analysis was performed to confirm the reliability of the proposed modification.
Key Words
buckling; cold-formed steel; direct strength method; distortional-global interaction; finite element analysis;
flexural members; reliability analysis
Address
Hashmi S.S. Ahmed, G. Khushbu, Ather Khan: Department of Civil Engineering, Maharashtra Institute of Technology, Aurangabad, Maharashtra, India
M. Anbarasu: Department of Civil Engineering, Government College of Engineering, Dharmapuri, Tamilnadu, India
Abstract
In recent decades, pultruded glass fiber-reinforced polymer (GFRP) members including those of box sections have attracted the attention of researchers. Nevertheless, the lack of uniform and consistent material properties, simplified design methods, and practical design codes have so far been the main barrier for field applications. Consequently, this paper highlights the existing knowledge concerning the flexural behavior of pultruded GFRP profiles and their failure modes. In particulate, it reviews the most commonly accepted design expressions and code provisions addressing the flange local buckling of pultruded GFRP box beams as the most likely failure mode. In addition, the material characterization of GFRP sections is described in detail along with the standard test methods to quantify the material characterization of GFRP laminates. It is shown that the critical flange local buckling stresses of pultruded GFRP box beams can be predicted with reliable accuracy using the expressions promulgated by ASCE (1984) (in which the flange plates are considered simply-supported at web-flange junction) and EUR 27666. The expressions stipulated in ASCE (2010) highly overestimates the critical flange local buckling stresses of GFRP box beams resulting in unconservative predictions.
Key Words
box section; design expressions; flange local buckling; material properties; pultruded GFRP
Address
Mozhdeh Dehshirizadeh, Abolfazl Eslami, Mehdi Khodadad Sar-Yazdi: Department of Civil Engineering, Yazd University, Iran
Hamid R. Ronagh: Department of Civil Engineering, Yazd University, Iran; 2epartment of Civil and Environmental Engineering, The University of New South Wales, Australia
Abstract
Cold-formed steel (CFS) I sections are increasingly being used as load-bearing components in building constructions, and such I sections frequently incorporate web holes to facilitate service installation. The economical and structural advantages of these elements have prompted many researchers to investigate the behavior of such structures. Despite numerous studies on the buckling stability of castellated beams, there is a notable absence of experimental investigation into oval castellated beams with stiffeners. This study examines the local buckling of cold-formed steel castellated I-beams stiffened with oval constellations through experimental and numerical analysis. Four specimens are fabricated with and without stiffeners, including parallel, perpendicular, and intersecting types attached to the web portion of the beam, along with cross stiffeners for the oval-shaped openings at the beam ends. Additionally, a numerical model is developed to predict the behavior of castellated beams with oval openings up to failure, considering both material and geometric nonlinearities. Codal analysis is performed using the North American specification for cold-formed steel AISI S-100 and the Australian/New Zealand design code AS/NZS 4600. The anticipated outcomes from numerical analysis, experimental research, and codal analysis are compared and presented. It will be more helpful to the preliminary designers.
Key Words
castellated beam; finite element analysis; local buckling; oval castellation; stiffeners
Address
S. Prabhakaran, R. Malathy and M. Kasiviswanathan: Department of Civil Engineering, Sona College of Technology, Salem, Tamil Nadu, India
Abstract
In order to solve the problem of calculating the reasonable completed bridge state of a self-anchored hybrid cable-stayed suspension bridge (SA-HCSB), this paper proposes an analytical method. This method simplifies the main beam into a continuous beam with multi-point rigid supports and solves the support reaction forces. According to the segmented catenary theory, it simultaneously solves the horizontal forces of the main span main cables and the stay cables and iteratively calculates the equilibrium force system on the main beam in the collaborative system bridge state while completing the shape finding of the main span main cable and stay cables. Then, the horizontal forces of the side span main cables and stay cables are obtained based on the balance of horizontal forces on the bridge towers, and the shape finding of the side spans are completed according to the segmented catenary theory. Next, the difference between the support reaction forces of the continuous beam with multiple rigid supports obtained from the initial and final iterations is used to calculate the load of ballast on the side span main beam. Finally, the axial forces and strains of each segment of the main beam and bridge tower are obtained based on the loads applied by the main cable and stay cables on the main beam and bridge tower, thereby obtaining analytical data for the bridge in the reasonable completed state. In this paper, the rationality and effectiveness of this analytical method are verified through a case study of a SA-HCSB with a main span of 720m in finite element analysis. At the same time, it is also verified that the equilibrium force of the main beam under the reasonably completed bridge state can be obtained through iterative calculation. The analytical algorithm in this paper has clear physical significance, strong applicability, and high accuracy of calculation results, enriching the shape-finding method of this bridge type.
Key Words
analytical method; continuous beam with multiple rigid supports; iterative calculation; reasonable completed bridge state; self-anchored hybrid cable-stayed suspension bridge; the segmented catenary theory
Address
Kai Wang: Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing 211189, China; Bozhou Vocational and Technical College, Bozhou 236800, China
Wen-ming Zhang, Jie Chen, Zhe-hong Zhang: Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing 211189, China
Abstract
In this study, compared two distinct estimation methods (stress charts and regression equations) proposed by the Indian road congress design guideline (IRC:58-2015) to determine flexural stress in Jointed Plain Concrete Pavement (JPCP). The occurrence of critical flexural stresses in pavement slabs is due to the combined effects of wheel loads and temperature. These stresses depend on various factors such as material properties of concrete, soil-subgrade strength, loading, and geometric properties of the slab. In order to account for the practical variability of these factors, critical edge stresses are determined using both methods and compared considering tied concrete shoulder. IRC:58 (2015) suggests, the stresses calculated by both the procedures should provide the same results. However, when these stresses are compared for the same configurations and same loading conditions, large variations are observed. The effect of tied concrete shoulder on reduction in critical edge stress is observed. Based on the study, certain important conclusions and recommendations are presented.
Address
Jeetendra S. Khichad, Rameshwar J. Vishwakarma, Siddharth Mehndiratta: Department of Civil Engineering, Malaviya National Institute of Technology, JLN Marg, Jaipur, Rajasthan-302017, India
Samadhan G. Morkhade: Department of Civil Engineering, Vidya Pratishthan
Abstract
Artificial intelligence is one of the efficient methods that can be developed to simulate nonlinear behavior and predict the response of building structures. In this regard, an adaptive method based on optimization algorithms is used to train the TSK model of the fuzzy inference system to estimate the seismic behavior of building structures based on analytical data. The optimization algorithm is implemented to determine the parameters of the TSK model based on the minimization of prediction error for the training data set. The adaptive training is designed on the feedback of the results of previous time steps, in which three training cases of 2, 5, and 10 previous time steps were used. The training data is collected from the results of nonlinear time history analysis under 100 ground motion records with different seismic properties. Also, 10 records were used to test the inference system. The performance of the proposed inference system is evaluated on two 3 and 20-story models of nonlinear steel moment frame. The results show that the inference system of the TSK model by combining the optimization method is an efficient computational method for predicting the response of nonlinear structures. Meanwhile, the multi-vers optimization (MVO) algorithm is more accurate in determining the optimal parameters of the TSK model. Also, the accuracy of the results increases significantly with increasing the number of previous steps.
Key Words
adoptive training; fuzzy inference system; nonlinear behavior; optimization problem; prediction; seismic response; TSK model
Address
Ebrahim Asadi, Reza Goli Ejlali, Seyyed Arash Mousavi Ghasemi: Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
Siamak Talatahari: School of Computing, Macquarie University, Sydney, Australia; Department of Computer Science, Khazar University, Mahsati 41, Baku, Azerbaijan
Abstract
The present paper is focused on the study of the propagation of plane waves in thermoelastic media under a modified
Green-Lindsay (MG-L) model having the influence of non-local and two temperature. The problem is formulated for the
considered model in dimensionless form and is explained by using the reflection phenomenon. The plane wave solution of these equations indicates the existence of three waves namely Longitudinal waves (LD-Wave), Thermal waves (T-wave), and Shear waves (SV-wave) from a stress-free surface. The variation of amplitude ratios is computed analytically and depicted graphically against the angle of incidence to elaborate the impact of non-local, two temperature, and different theories of thermoelasticity. Some particular cases of interest are also deduced from the present investigation. The present study finds applications in a wide range of problems in engineering and sciences, control theory, vibration mechanics, and continuum mechanics.
Key Words
free surface; Modified Green-Lindsay theory; non-local; two temperature
Address
Sachin Kaushal: Department of Mathematics, School of Chemical Engineering and Physical Sciences, Lovely Professional University-Phagwara, India
Rajneesh Kumar: Department of Mathematics, Kurukshetra University Kurukshetra, Haryana, India
Indu Bala: Department of Mathematics, School of Chemical Engineering and Physical Sciences, Lovely Professional University-Phagwara, India
Gulshan Sharma: Department of Mathematics, School of Chemical Engineering and Physical Sciences, Lovely Professional University-Phagwara, India; Post Graduate Department of Mathematics, Doaba College, Jalandhar, India
