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CONTENTS
Volume 52, Number 6, December25 2014
 

Abstract
The long-term performance of plates resting on viscoelastic foundations is a major concern in the analysis of soil-structure interaction. As a powerful mathematical tool, fractional calculus may address these plate-on-foundation problems. In this paper, a fractionalized Zener model is proposed to study the time-dependent behavior of a uniformly loaded rectangular thin foundation plate. By use of the viscoelasticelastic correspondence principle and the Laplace transforms, the analytical solutions were obtained in terms of the Mittag-Leffler function. Through the analysis of a numerical example, the calculated plate deflection, bending moment and foundation reaction were compared to those from ideal elastic and standard viscoelastic models. It is found that the upper and lower bound solutions of the plate response estimated by the proposed model can be determined using the elastic model. Based on a parametric study, the impacts of model parameters on the long-term performance of a foundation plate were systematically investigated. The results show that the two spring stiffnesses govern the upper and lower bound solutions of the plate response. By varying the values of the fractional differential order and the coefficient of viscosity, the timedependent behavior of a foundation plate can be accurately captured. The fractional differential order seems to be dependent on the mechanical properties of the ground soil. A sandy foundation will have a small fractional differential order while in order to simulate the creeping of clay foundation, a larger fractional differential order value is needed. The fractionalized Zener model is capable of accounting for the primary and secondary consolidation processes of the foundation soil and can be used to predict the plate performance over many decades of time.

Key Words
viscoelastic foundation; plate-on-foundation; fractional calculus; rheological model; timedependent behavior; Mittag-Leffler function

Address
Cheng-Cheng Zhang, Hong-Hu Zhu, Bin Shi: School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
Guo-Xiong Mei: College of Civil Engineering and Architecture, Guangxi University, Nanning, China

Abstract
Plastic mechanism analysis of structures subjected to large deformation has long been used in order to determine collapse mechanisms of steel structures, and the energy absorbed in plastic deformation during such collapses. In this paper the technique is applied to vehicle roof structures that undergo large plastic deformation as a result of rollover crashes. The components of such roof structures are typically steel spot-welded hat-type sections. Ten different deformation mechanisms are defined from investigations of real-world rollover crashes, and an analytical technique to determine the plastic collapse load and energy absorption of such mechanisms is determined. The procedure is presented in a generic manner, such that it may be applied to any vehicle structure undergoing a rollover induced collapse. The procedure is applied to an exemplar vehicle, in order to demonstrate its application in determining the energy absorbed in the deformation of the identified collapse mechanisms. The procedure will be useful to forensic crash reconstructionists, in order to accurately determine the initial travel velocity of a vehicle that has undergone a rollover and for which the post-crash vehicle deformation is known. It may also be used to perform analytical studies of the collapse resistance of vehicle roof structures for optimisation purposes, which is also demonstrated with an analysis of the effect of varying the geometric and material properties of the roof structure components of the exemplar vehicle.

Key Words
plastic mechanism analysis, energy absorption, roof collapse, bending collapse, vehicle rollover

Address
M.R. Bambach: Transport and Road Safety (TARS), Faculty of Science, Old Main Building, University of New South Wales, Sydney, NSW 2052, Australia

Abstract
In this paper, reliability-based design optimization (RBDO) of structures is addressed. For this purpose, the global search and optimization capabilities of genetic algorithm (GA) are combined with the efficiency and reasonable accuracy of an advanced moment-based finite element reliability method. For performing RBDO, three variants of GA including a real-coded, a binary-coded and an improved binarycoded GA are developed. In these methods, GA performs (finite element) reliability analyses to evaluate reliability constraints. For truss structures which include finite element modeling, reliability constraints are evaluated using finite element reliability analysis. Response sensitivity required for finite element reliability analysis is obtained by direct differentiation method (DDM) rather than finite difference method (FDM). The proposed methods are examined within four standard test examples and real-world design problems. The results illustrate the superiority and efficiency of the improved binary-coded GA. Results also illustrate that DDM significantly reduces the computational cost and improves the efficiency of the optimization procedure.

Key Words
reliability-based optimization; finite element reliability analysis; genetic algorithm; optimization of structures; direct differentiation method

Address
Reza Abbasnia, Mohsenali Shayanfar and Ali Khodam: School of Civil Engineering, Iran University of Science and Technology, P.O. Box 16765-163, Narmak, Tehran, Iran

Abstract
Structural design is usually an optimization process. Numerous parameters such as the member shapes and sizes, the elasticity modulus of material, the locations of nodes and the support constraints can be selected as design variables. These variables are progressively revised in order to obtain a satisfactory structure. Each modification requires a fresh analysis for the displacements and stresses, and reanalysis can be employed to reduce the computational cost. This paper is focused on static reanalysis problem with modification of deleting some supports. An efficient reanalysis method is proposed. The method makes full use of the initial information and preserves the ease of implementation. Numerical examples show that the calculated results of the proposed method are the identical as those of the direct analysis, while the computational time is remarkably reduced.

Key Words
structural reanalysis; modification of supports; Cholesky factorization; stiffness matrix; computational cost

Address
Haifeng Liu: Department of Mathematics, School of Mathematics and Statistics, Xi\'an Jiaotong University,
Xi\'an 710049, P.R. China
Shigang Yue: School of Computer Science, University of Lincoln, Brayford Pool Campus, Lincoln LN6 7TS, UK

Abstract
The ratcheting effect greatly challenges the design of piping components. With the assistance of the quasi-three point bending apparatus, ratcheting and the ratcheting boundary of pressurized straight Z2CND18.12N stainless steel pipe under bending loading and vertical displacement control were studied experimentally. The characteristics of progressive inelastic deformation in axial and hoop directions of the Z2CND18.12N stainless steel pipes were investigated. The experiment results show that the ratcheting strain occurs mainly in the hoop direction while there is less ratcheting strain in the axial direction. The characteristics of the bending ratcheting behavior of the pressure pipes were derived and compared under load control and displacement control, respectively. The results show that the cyclic bending loading and the internal pressure affect the ratcheting behavior of the pressurized straight pipe significantly under load control. In the meantime, the ratcheting characteristics are also highly associated with the cyclic displacement and the internal pressure under displacement control. All these factors affect not only the saturation of the ratcheting strain but the ratcheting strain rate. A series of multi-step bending ratcheting experiments were conducted under both control modes. It was found that the hardening effect of Z2CND18.12N stainless steel pipe under previous cyclic loadings no matter with high or low displacement amplitudes is significant, and the prior loading histories greatly retard the ratcheting strain and its rate under subsequent loadings. Finally, the ratcheting boundaries of the pressurized straight Z2CND18.12N stainless steel pipe were determined and compared based on KTA/ASME, RCC-MR and the experimental results.

Key Words
ratcheting; cyclic loading; cyclic displacement; loading history; ratcheting boundary

Address
Lei Wang, Gang Chen, Jianbei Zhu, Xiuhu Sun and Xu Chen: School of Chemical Engineering and Technology, Tianjin University, 300072, China
Yunhui Mei: Tianjin Key Laboratory of Advanced Joining Technology and School of Material Science and Engineering, Tianjin University, 300072, China
Xiang Ling: Jiangsu Key Laboratory of Process Enhancement & New Energy Equipment Technology, NanJing University of Technology, 210009, China

Abstract
The objective of this research is to develop a practical design and assessment approach of steel frames with steel slit walls (SSWs) that focuses on the damage-control behavior to enhance the structural resilience. The yielding sequence of SSWs and frame components is found to be a critical issue for the damage-control behavior and the design of systems. The design concept is validated by the full-scale experiments presented in this paper. Based on a modified energy-balance model, a procedure for designing and assessing the system motivated by the framework regarding the equilibrium of the energy demand and the energy capacity is proposed. The damage-control spectra constructed by strength reduction factors calculated from single-degree-of-freedom systems considering the post stiffness are addressed. A quantitative damage-control index to evaluate the system is also derived. The applicability of the proposed approach is validated by the evaluation of example structures with nonlinear dynamic analyses. The observations regarding the structural response and the prediction during selected ground motions demonstrate that the proposed approach can be applied to damage-control design and assessment of systems with satisfactory accuracy.

Key Words
steel frame, steel slit wall, energy approach, damage-control, resilience, yielding sequence, experimental study

Address
Ke Keand Yiyi Chen: State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China

Abstract
Reinforced concrete (RC) shear walls are one of the most commonly used lateral-load resisting systems in high-rise buildings. RC Parallel redundancy walls studied herein consist of two parts nested to each other. These two parts have different mechanical behaviors and energy dissipation mechanisms. In this paper, experimental studies of four 1/2-scale specimens representing this concept, which are subjected to inplane cyclic loading, are presented and test results are discussed. Two specimens consist of a wall frame with barbell-shaped walls embedded in it, and the other two consist of a wall frame and braced walls nested each other. The research mainly focuses on the failure mechanism, strength, hysteresis loop, energy dissipation capacity and stiffness of these walls. Results show that the RC parallel redundancy wall is an efficient lateral load resisting component that acts as a \"dual\" system with good ductility and energy dissipation capacity. One main part absorbs a greater degree of the energy exerted by an earthquake and fails first, whereas the other part can still behave as an independent role in bearing loads after earthquakes.

Key Words
experimentation; redundancy; shear walls; earthquakes; failure mechanism; dual system

Address
Yiqiu Lu and Liang Huang: Department of Civil Engineering, Hunan University, Changsha, 410082, China

Abstract
A simulation of failures on responsible elements is only one form of the extreme structural behavior analysis. By understanding the dynamic behavior in incidental situations, it is possible to make a special structural design from the point of the largest axial force, stress and redundancy. The numerical realization of one such simulation analysis was performed using FEM in this paper. The boundary parameters of transient analysis, such as overall structural damping coefficient, load accelerations, time of load fall and internal forces in the responsible structural elements, were determined on the basis of the dynamic experimental parameters. The structure eigenfrequencies were determined in modal analysis. In the study, the basic incidental models were set. The models were identified by many years of monitoring incidental situations and the most frequent human errors in work with heavy structures. The combined load models of structure are defined in the paper since the incidents simply arise as consequences of cumulative errors and failures. A feature of a combined model is that the single incident causes the next incident (consecutive timing) as well as that other simple dynamic actions are simultaneous. The structure was observed in three typical load positions taken from the crane passport (range-load). The obtained dynamic responses indicate the degree of structural sensitivity depending on the character of incident. The dynamic coefficient KD was adopted as a parameter for the evaluation of structural sensitivity.

Key Words
frame structure; incidental dynamics; nonlinear analysis; simulation; transient analysis

Address
Goran N. Radoicic, Miomir LJ. Jovanovic: Department of Transport Engineering and Logistics, Faculty of Mechanical Engineering, University of Niš, A. Medvedeva 14, Niš, Serbia
Dragan Z. Marinkovic: Department of Structural Analysis, Institute of Mechanics, Berlin Institute of Technology, Strasse des 17. Juni 135, Berlin, Germany

Abstract
In Current paper, the voltages of patches optimization are carried out for minimizing the power consumption of piezoelectric patches and maximum vertical displacement of symmetrically FML panels using the modified multi-objective Elitist-Artificial Bee Colony (E-ABC) algorithm. The voltages of patches, panel length/width ratios, ply angles, thickness of metal sheets and edge conditions are chosen as design variables. The classical laminated plate theory (CLPT) is considered to model the transient response of the panel, and numerical results are obtained by the finite element method. The performance of the EABC is also compared with the PSO algorithm and shows the good efficiency of the E-ABC algorithm. To check the validity, the transient responses of isotropic and orthotropic panels are compared with those available in the literature and show a good agreement.

Key Words
smart fiber metal laminated panel; modified elitist-artificial bee colony algorithm

Address
H. Ghashochi-Bargh and M.H. Sadr: Aerospace Engineering Department, Centre of Excellence in Computational Aerospace Engineering, Amirkabir University of Technology, Hafez Avenue, Tehran, Iran

Abstract
Calculating the seismic displacement of retaining walls has an important role in the optimum design of these structures. Also, studying the effect of surcharge is important for the calculation of active pressure as well as permanent displacements of the wall. In this regard, some researchers have investigated active pressure; but, unfortunately, there are few investigations on the seismic displacement of retaining walls with surcharge. In this research, using limit analysis and upper bound theorem, permanent seismic displacement of retaining walls with surcharge was analyzed for sliding and overturning failure mechanisms. Thus, a new formulation was presented for calculating yield acceleration, critical angle of failure wedge, and permanent displacement of retaining walls with surcharge. Also, effects of surcharge, its location and other factors such as height of the wall and internal friction angle of soil on the amount of seismic displacements were investigated. Finally, designing charts were presented for calculating yield acceleration coefficient and angle of failure wedge.

Key Words
retaining wall; seismic displacement; limit analysis; surcharge; design charts

Address
Mohamad Mahdi Aminpoor and Ali Ghanbari: Faculty of Engineering, Kharazmi University, No. 49 Mofatteh Ave., Tehran, I.R. Iran

Abstract
The hydraulic deterioration of the drainage system in tunnel linings is one of the main factors governing long-term lining-ground interactions during the lifetime of tunnels. Thus, in the design procedure of a tunnel below the groundwater table, the possible detrimental effects associated with the hydraulic deterioration should be addressed. Hydraulic deterioration in double-lined tunnels can occur because of reasons such as clogging of the drainage layer and drain-pipe blockings. In this study, the coupled mechanical and hydraulic interactions between linings due to drain-pipe blockings are investigated using the finite-element method. A double-lined structural model incorporating hydraulic behavior is developed to represent the coupled structural and hydraulic behavior between the linings and drainage system. It is found that hydraulic deterioration hinders flow into the tunnel, causing asymmetric development of pore-water pressure and consequent detrimental effects to the secondary lining.

Key Words
doubled-lined tunnel; lining; hydraulic deterioration; drain-pipe blocking; numerical analysis

Address
Jong-Ho Shin: Department of Civil Engineering, Konkuk University, Seoul, Republic of Korea
In-Keun Lee: Institute of Land and Housing, LH Cooperation, Daejeon, Republic of Korea
Eun-Jung Joo: Department of Civil Engineering, Konkuk University, Seoul, Republic of Korea

Abstract
Plates are most widely used in the hulls of floating concrete structures, bridge decks, walls of offshore structures and liquid storage tanks. A method of analysis is presented for the determination of loaddeflection response and ultimate strength of high-strength steel fiber reinforced concrete (HSSFRC) plates simply supported on all four edges and subjected to combined action of external compressive in-plane and transverse loads. The behavior of HSSFRC plate specimens subjected to combined uniaxial in-plane and transverse loads was investigated. The proposed analytical method is compared to the physical test results, and shows good agreement. To predict the constitutive behavior of HSSFRC in compression, a nondimensional characteristic equation was proposed and found to give reasonable accuracy.

Key Words
steel fiber reinforced concrete plate; out-of-plane central deflection; load-deflection response; analytical model; ultimate strength prediction

Address
Ramadoss Perumal and S. Palanivel: Department of Civil Engineering, Pondicherry Engineering College, Puducherry- 605014, India


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