Abstract
The severe deterioration of structures has led to extensive research on the development of structural repair techniques
using composite materials. Consequently, previous researchers have devised various analytical methods to predict the interface performance of bonded repairs. However, these analytical solutions are highly complex mathematically and necessitate numerous calculations with a large number of iterations to obtain the output parameters. In this paper, an artificial neural network prediction models is used to calculate the interfacial stress distribution in RC beams strengthened with FRP sheet. The
R2value for the training data is evaluated as 0.99, and for the testing data, it is 0.92. Closed-form solutions are derived for RC beams strengthened with composite sheets simply supported at both ends and verified through direct comparisons with existing results. A comparative study of peak interfacial shear and normal stresses with the literature gives the usefulness and effectiveness of ANN proposed. A parametrical study is carried out to show the effects of some design variables, e.g., thickness of adhesive layer and FRP sheet.
Address
Bensattalah Aissa: Faculty of Applied Sciences, Department of Civil Engineering, University of Tiaret, Algeria; Laboratoire des Méthodes de Conception des Systèmes (LMCS),16000 Oued-Smar, Algiers, Algeria
Benferhat Rabia. Hassaine Daouadji Tahar: Faculty of Applied Sciences, Department of Civil Engineering, University of Tiaret, Algeria; Civil Engineering Department, University of Tiaret, Algeria; Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria
Abstract
A novel laminated-hybrid-composite-beam (LHCB) of glass-epoxy infused with flyash and graphene is constructed
for this study. The conventional mixture-rule and constitutive-relationship are modified to incorporate filler and lamina orientation. Eringen's non-local-theory is used to include the filler effect. Hamilton's principle based on fifth-order-layer-wiseshear-deformation-theory is applied to formulate the equation of motion. The analogous shear-spring-models for LHCB with multiple-cracks are employed in finite-element-analysis (FEA). Modal-experimentations are conducted (B&K-analyser) and the findings are compared with theoretical and FEA results. In terms of dimensionless relative-natural-frequencies (RNF), the dynamic-response in cantilevered support is investigated for various relative-crack-severities (RCSs) and relative-crackpositions
(RCPs). The increase of RCS increases local-flexibility in LHCB thus reductions in RNFs are observed. RCP is found
to play an important role, cracks present near the end-support cause an abrupt drop in RNFs. Further, multiple cracks are observed to enhance the nonlinearity of LHCB strength. Introduction of the first to third crack in an intact LHCB results drop of RNFs by 8%, 10%, and 11.5% correspondingly. Also, it is demonstrated that the RNF varies because of the lamina-orientation, and filler addition. For 0o lamina-orientation the RNF is maximum. Similarly, it is studied that the addition of graphene reduces weight and increases the stiffness of LHCB in contrast to the addition of flyash. Additionally, the response of LHCB to moving mass is accessed by appropriately modifying the numerical programs, and it is noted that the successive introduction of the first to ninth crack results in an approximately 40% to 120% increase in the dynamic-amplitude-ratio.
Key Words
dynamics; Eringen's non-local theory; fillers; graphene and flyash; Hamilton's principle; hybrid-composite beam; moving mass; multiple1-transverse-cracks
Address
Saritprava Sahoo, Pankaj Charan Jena: Department of Production Engineering, Veer Surendra Sai University of Technology, Burla, Odisha, 768018, India
Sarada Prasad Parida: Department of Mechanical Engineering, Templecity Institute of Technology, Khordha, Odisha, 752050, India
Abstract
An unbraced cantilever beam subjected to loads which cause bending about the major axis may buckle in a flexuraltorsional mode by deflecting laterally and twisting. For the efficient design of these structures, design engineers require a simple accurate equation for the elastic flexural-torsional buckling load. Existing solutions for the flexural-torsional buckling of cantilever beams have mainly been derived by numerical methods which are tedious to implement. In this research, an attempt is made to derive a theoretical equation by the energy method using different buckled shapes. However, the results of a finite element flexural-torsional buckling analysis reveal that the buckled shapes for the lateral deflection and twist rotation are different for cantilever beams. In particular, the buckled shape for the twist rotation also varies with the section size. In light of these findings, the finite element flexural-torsional buckling analysis was then used to derive simple accurate equations for the elastic buckling load and moment for cantilever beams subjected to end point load, uniformly distributed load and end moment. The results are compared with previous research and it was found that the equations derived in this study are accurate and simple to use.
Key Words
cantilever beam; end moment; end point load; finite element analysis; flexural-torsional buckling; uniformly distributed load
Address
Gilbert Xiao, Silky Ho and John P. Papangelis: School of Civil Engineering, University of Sydney, Australia
Abstract
efficient optimization algorithm and damage-sensitive objective function are two main components in optimization-based Finite Element Model Updating (FEMU). A suitable combination of these components can considerably affect damage detection accuracy. In this study, a new hybrid damage-sensitive objective function is proposed based on combining two different objection functions to detect the location and extent of damage in structures. The first one is based on Generalized Pseudo Modal Strain Energy (GPMSE), and the second is based on the element's Generalized Flexibility Matrix (GFM). Four well-known population-based metaheuristic algorithms are used to solve the problem and report the optimal solution as damage detection results. These algorithms consist of Cuckoo Search (CS), Teaching-Learning-Based Optimization (TLBO), Moth Flame Optimization (MFO), and Jaya. Three numerical examples and one experimental study are studied to illustrate the capability of the proposed method. The performance of the considered metaheuristics is also compared with each other to choose the most suitable optimizer in structural damage detection. The numerical examinations on truss and frame structures with considering the effects of measurement noise and availability of only the first few vibrating modes reveal the good performance of the proposed technique in identifying damage locations and their severities. Experimental examinations on a six-story shear building structure tested on a shake table also indicate that this method can be considered as a suitable technique for damage assessment of shear building structures.
Key Words
damage detection; finite element model updating; generalized flexibility matrix; modal strain energy; optimization algorithm
Address
Seyed Milad Hosseini: School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran
Mohamad Mohamadi Dehcheshmeh: Department of Civil Engineering, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
Gholamreza Ghodrati Amiri: Natural Disasters Prevention Research Center, School of Civil Engineering, Iran University of Science & Technology, Tehran, Iran
Abstract
The postoperative period for a carrier of total hip prosthesis (THP), especially in the first months, remains the most difficult period for a patient after each operation, even if traumatologist surgeons want the relief and success of their operations. In this investigation, selected three of the daily activities for a wearer of total hip replacement (THR), such as sitting in a chair, lifting a chair, and going downstairs, and was performed a numerical simulation by finite elements based on experimental data
by Bergmann (Bergmann 2001) in terms of effort for each activity. Different stresses have been extracted, and a detailed comparison between two activities with different induced stresses such as normal, tensile, and compressive shear stresses.
Key Words
activity; bone; cement; stem; stress; total hip prosthesis
Address
Abdelmadjid Moulgada, Mohammed El Sallah Zagane: Department of Mechanical Engineering, University of Ibn Khaldoun Tiaret, 14000, Algeria; Department of Mechanical Engineering, LMPM Laboratory, University of Djillali Liabes Sidi Bel Abbes, 22000, Algeria
Murat Yaylaci: Biomedical Engineering MSc Program, Recep Tayyip Erdogan University, 53100, Rize, Turkey; Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Ait Kaci Djafar, Sahli Abderahmane: Department of Mechanical Engineering, LMPM Laboratory, University of Djillali Liabes Sidi Bel Abbes, 22000, Algeria
Şevval Öztürk: Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Ecren Uzun Yaylaci: Faculty of Engineering and Architecture, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Abstract
Geopolymer concrete (GC) can be competently utilized as a practical replacement for cement to prevent a high carbon footprint and to give a direction toward sustainable concrete construction. Moreover, previous studies mostly focused on the axial response of glass fiber reinforced polymer (glass-FRP) concrete compressive elements without determining the effectiveness of repairing them after their partial damage. The goal of this study is to assess the structural effectiveness of partially damaged GC columns that have been restored using carbon fiber reinforced polymer (carbon-FRP). Bars made of glass-FRP and helix made of glass-FRP are used to reinforce these columns. For comparative study, six of the twelve circular specimens-each measuring 300 mmx1200 mm-are reinforced with steel bars, while the other four are axially strengthened using glass-FRP bars (referred to as GSG columns). The broken columns are repaired and strengthened using carbon-FRP sheets after the specimens have been subjected to concentric and eccentric compression until a 30% loss in axial strength is attained in the post-peak phase. The study investigates the effects of various variables on important response metrics like axial strength, axial deflection, load-deflection response, stiffness index, strength index, ductility index, and damage response. These variables include concentric and eccentric compression, helix pitch, steel bars, carbon-FRP wrapping, and glass-FRP bars. Both before and after the quick repair process, these metrics are evaluated. The results of the investigation show that the axial strengths of the reconstructed SSG and GSG columns are, respectively, 15.3% and 20.9% higher than those of their original counterparts. In addition, compared to their SSG counterparts, the repaired GSG samples exhibit an improvement in average ductility indices of 2.92% and a drop in average stiffness indices of 3.2%.
Key Words
axial deflection; carbon-FRP sheets; geopolymer concrete; glass-FRP helix; strength index
Address
Mohamed Hechmi El Ouni: Department of Civil Engineering, College of Engineering, King Khalid University, PO Box 394, Abha 61411, Saudi Arabia
Ali Raza, Khawar Ali: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan
Abstract
In this study, the uniaxial ratcheting effect of Z2CND18.12N austenitic stainless steel at room and elevated temperatures is firstly simulated based on the Ahmadzadeh-Varvani hardening rule (A-V model), which is embedded into the finite element software ABAQUS by writing the user material subroutine UMAT. The results show that the predicted results of A-V model are lower than the experimental data, and the A-V model is difficult to control ratcheting strain rate. In order to improve the predictive ability of the A-V model, the parameter y2 of the A-V model is modified using the isotropic hardening criterion, and the extended A-V model is proposed. Comparing the predicted results of the above two models with the experimental data, it is shown that the prediction results of the extended A-V model are in good agreement with the experimental data.
Key Words
austenitic stainless steel; constitutive model; cyclic plasticity theory; finite element analysis; ratcheting behavior
Address
Xiaohui Chen, Lang Lang and Hongru Liu: School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
Abstract
The focus of this study is on the structural behaviour of reinforced concrete beams in which basalt fiber and SBR
latex were added and the cement was partially replaced with 10% of hypo sludge. Eight different mixes of reinforced beam
specimens were tested under static loading behaviour. The experiments showed, the structural behaviour with features such as load-deflection relationships, crack pattern, crack propagation, number of crack, crack spacing and moment curvature. A stressstrain relationship to represent the overall behavior of reinforced concrete in tension, which includes the combined effects of cracking and mode of failure along the reinforcement, is proposed. The structural behaviour results of reinforced concrete beams with various types of mix were tested at the age of 28 days. The investigation revealed that the flexural behaviors of hypo sludge reinforced concrete beams with addition of basalt fiber and SBR latex was higher than that of control concrete reinforced beam. The specimen (LHSBFC) with 10% hypo sludge, 0.25% Basalt fiber and 10% SBR latex showed an increase of 5.08% load carrying capacity, 7.6% stiffness, 3.97% ductility, 31.29% energy dissipation when compared to the control concrete beam. The analytical investigation using FEM shows that it was in good agreement with the experimental investigation.
Key Words
basalt fibre; crack propagation; deflection; hypo sludge; moment curvature
Address
S. Srividhya: Department of Civil Engineering, Builders Engineering College, Kangeyam, Tirupur 638108, Tamilnadu, India
R. Vidjeapriya: Department of Civil Engineering, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025, Tamilnadu, India
