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Volume 27, Number 1, April10 2018

This paper presents a semi-analytical solution of simply supported horizontally composite curved I-beam by trigonometric series. The flexibility of the interlayer connectors between layers both in the tangential direction and in the radial direction is taken into account in the proposed formulation. The governing differential equations and the boundary conditions are established by applying the variational approach, which are solved by applying the Fourier series expansion method. The accuracy and efficiency of the proposed formulation are validated by comparing its results with both experimental results reported in the literature and FEM results.

Key Words
curved I-beam; composite beam; slip; variational approach

College of Traffic, Jilin University, Changchun 130025, P.R. China.

The main objective of this study is to develop a dual approach for geometrically nonlinear finite element analysis of plane truss structures. The geometric nonlinearity is considered using the Total Lagrangian formulation. The nonlinear solution is obtained by introducing and minimizing an objective function subjected to displacement-type constraints. The proposed method can fully trace the whole equilibrium path of geometrically nonlinear plane truss structures not only before the limit point but also after it. No stiffness matrix is used in the main approach and the solution is acquired only based on the direct classical stress-strain formulations. As a result, produced errors caused by linearization and approximation of the main equilibrium equation will be eliminated. The suggested algorithm can predict both pre- and post-buckling behavior of the steel plane truss structures as well as any arbitrary point of equilibrium path. In addition, an equilibrium path with multiple limit points and snap-back phenomenon can be followed in this approach. To demonstrate the accuracy, efficiency and robustness of the proposed procedure, numerical results of the suggested approach are compared with theoretical solution, modified arc-length method, and those of reported in the literature.

Key Words
plane truss; geometric; nonlinear finite element; total Lagrangian; dual approach; snap-through

(1) AliReza Habibi:
Department of Civil Engineering, Shahed University, Tehran, Iran;
(2) Shaahin Bidmeshki:
Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran.

In this study, a mixed-interpolated tensorial component 4 nodes method (MITC4) is treated as a numerical analysis model for topology optimization using multiple materials assigned within Reissner-Mindlin plates. Multi-material optimal topology and shape are produced as alternative plate retrofit designs to provide reasonable material assignments based on stress distributions. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. Mathematical formulation of multi-material topology optimization problem solving minimum compliance is an alternating active-phase algorithm with the Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples illustrate the reliability and accuracy of the present design method for multi-material topology optimization with Reissner-Mindlin plates using MITC4 elements and steel materials.

Key Words
multi-materials topology optimization; MITC4; Reissner-Mindlin theory; finite element method; steel plate; shearlocking

Department of Architectural Engineering, Sejong University, Seoul 05006, Republic of Korea.

In this paper, the response of a sandwich cylindrical shell over any sort of boundary conditions and under a general distributed static loading is investigated. The faces and the core are made of some isotropic materials. The faces are modeled as thin cylindrical shells obeying the Kirchhoff-Love assumptions. For the core material it is assumed to be thick and the in-plane stresses are negligible. The governing equations are derived using the principle of the stationary potential energy. Using harmonic differential quadrature method (HDQM) the equations are solved for deformation components. The obtained results primarily are compared against finite element results. Then, the effects of changing different parameters on the stress and displacement components of sandwich cylindrical shells are investigated.

Key Words
sandwich cylindrical shells; harmonic differential quadrature method; static analysis; general lateral loading; general boundary conditions

Department of Mechanical Engineering, Faculty of Engineering, Kharazmi University, Mofatteh Avenue, P.O. Box 15719-14911, Tehran, Iran.

Generally, beam-column joints are taken into account as rigid in assessment of seismic performance of reinforced concrete (RC) structures. Experimental and numerical studies have proved that ignoring nonlinearities in the joint core might crucially affect seismic performance of RC structures. On the other hand, to improve seismic behaviour of such structures, several strengthening techniques of beam–column joints have been studied and adopted in practical applications. Among these strengthening techniques, the application of FRP materials has extensively increased, especially in case of exterior RC beam-column joints. In current paper, to simulate the inelastic response in the core of RC beam–column joints strengthened by FRP sheets, a practical joint model has been proposed so that the effect of FRP sheets on characteristics of an RC joint were considered in principal tensile stress-joint rotation relations. To determine these relations, a combination of experimental results and a mechanically-based model has been developed. To verify the proposed model, it was applied to experimental specimens available in the literature. Results revealed that the model could predict inelastic response of as-built and FRP strengthened joints with reasonable precision. The simple analytic procedure and the use of experimentally computed parameters would make the model sufficiently suitable for practical applications.

Key Words
beam-column joint; nonlinear analysis; fiber-reinforced polymer (FRP); principal tensile stress; practical model

Department of Civil Engineering, University of Mazandaran, Babolsar, Iran.

This paper presents a new method to compute the shear strength of composited structural B-C-W members. These B-C-W members, defined as concrete-filled steel box beams, columns and shear walls, consist of a slender rectangular steel plate box filled with concrete and inserted steel plates connecting the two long-side steel plates. These structural elements are intended to be used in structural members of super-tall buildings and nuclear safety-related structures. The concrete confined by the steel plate acts to be in a multi-axial stressed state: therefore, its shear strength was calculated on the basis of a concrete\'s failure criterion model. The shear strength of the steel plates on the long sides of the structural element was computed using the von Mises plastic strength theory without taking into account the buckling of the steel plate. The spacing and strength of the inserted plates to induce plate yielding before buckling was determined using elastic plate theory. Therefore, a predictive method to compute the shear strength of composited structural B-C-W members without considering the shear span ratio was obtained. A coefficient considering the influence of the shear span ratio was introduced into the formula to compute the anti-lateral bearing capacity of composited structural B-C-W members. Comparisons were made between the numerical results and the test results along with this method to predict the anti-lateral bearing capacity of concrete-filled steel box walls. Nonlinear static analysis of concrete-filled steel box walls was also conducted by using ABAQUS and the results agreed well with the experimental data.

Key Words
shear strength; multi-axial stressing state; concrete failure criterion; shear span ratio; buckling; nonlinear static analysis

(1) Limeng Zhu, Chunwei Zhang, Xiaoming Guan:
School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, P.R. China;
(2) Brian Uy:
School of Civil Engineering, University of Sydney, Sydney, 2006, Australia;
(3) Li Sun:
School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, P.R. China;
(4) Baolin Wang:
Graduate School at Shenzhen, Harbin Institute of Technology, Harbin 150001, P.R. China.

Uniaxial ratcheting behavior of Z2CND18.12N austenitic stainless steel used nuclear power plant piping material was studied. The results indicated that ratcheting strain increased with increasing of stress amplitude under the same mean stress and different stress amplitude, ratcheting strain increased with increasing of mean stress under the same stress amplitude and different mean stress. Based on least square method, a suitable method to arrest ratcheting by loading the materials was proposed, namely determined method of zero ratcheting strain rate. Zero ratcheting strain rate occur under specified mean stress and stress amplitudes. Moreover, three dimensional ratcheting boundary surface graph was established with stress amplitude, mean stress and ratcheting strain rate. This represents a graphical surface zone to study the ratcheting strain rates for various mean stress and stress amplitude combinations. The graph showed the ratcheting behavior under various combinations of mean and amplitude stresses. The graph was also expressed with the help of experimental results of certain sets of mean and stress amplitude conditions. Further, experimentation cost and time can be saved.

Key Words
uniaxial ratcheting; cyclic loading; least square method; zero ratcheting strain rate; three dimensional ratcheting boundary surface

(1) Xiaohui Chen:
School of Control Engineering, Northeastern University, Qinhuangdao 066004, China
(2) Xiaohui Chen:
School of Mechanical Engineering & Automation, Yanshan University, Qinhuangdao, 066004, China;
(3) Xu Chen:
School of Mechanical Engineering & Automation, School of Tianjin University, Tianjin, 300072, China;
(4) Haofeng Chen:
Department of Mechanical & Aerospace Engineering, University of Strathclyde, G1 1XJ, UK.

A new composite reinforced method, namely self-compacting concrete filled circular CFRP-steel jacketing, was proposed in this paper. Experimental tests on eight RC square short columns reinforced with the new composite reinforced method and four RC square short columns reinforced with CFS jackets were conducted to investigate their eccentrically compressive behaviour. Nine reinforced columns were subjected to eccentrically compressive loading, while three reinforced columns were subjected to axial compressive loading as reference. The parameters investigated herein were the eccentricity of the compressive loading and the layer of CFRP. Subsequently, the failure mode, ultimate load, deformation and strain of these reinforced columns were discussed. Their failure modes included the excessive bending deformation, serious buckling of steel jackets, crush of concrete and fracture of CFRP. Moreover, these reinforced columns exhibited a ductile failure globally. Both the eccentricity of the compressive loading and the layer of CFRP had a significant effect on the eccentrically compressive behaviour of reinforced columns. Finally, formulae for the evaluation of the ultimate load of reinforced columns were proposed. The theoretical formulae based on the ultimate equilibrium theory provided an effective, acceptable and safe method for designers to calculate the ultimate load of reinforced columns under eccentrically compressive loading.

Key Words
new composite reinforced method; eccentrically compressive behaviour; experimental tests; theoretical formulae

(1) Fan Zhang:
School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China;
(2) Fan Zhang, Yiyan Lu, Shan Li, Wenlong Zhang:
School of Civil Engineering, Wuhan University, Wuhan 430072, China.

In This work an analysis of the propagation of waves of functionally graduated plates is presented by using a high order hyperbolic (HSDT) shear deformation theory. This theory has only four variables, which is less than the theory of first order shear deformation (FSDT). Therefore, a shear correction coefficient is not required. Unlike other conventional shear deformation theories, the present work includes a new field of displacement which introduces indeterminate integral variables. The properties of materials are supposed classified in the direction of the thickness according to two simple distributions of a power law in terms of volume fractions of constituents. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton's principle. The analytical dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. The convergence and the validation of the proposed theoretical numerical model are performed to demonstrate the efficacy of the model.

Key Words
wave propagation; phase velocity; vibration; functionally graded plate; plate theory; porosity

(1) Hocine Fourn, Mohamed Bourada, Abdelouahed Tounsi:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(2) Hassen Ait Atmane:
Advanced Materials and Structures Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(3) Hassen Ait Atmane:
Département de génie civil, Faculté de génie civil et d'architecture, Univesité Hassiba Benbouali de Chlef, Algérie;
(4) Abdelmoumen Anis Bousahla:
Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria;
(5) Abdelmoumen Anis Bousahla:
Centre Universitaire de Relizane, Algérie;
(6) Abdelouahed Tounsi:
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia;
(7) S.R. Mahmoud:
Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.

Steel-concrete-steel (SCS) sandwich composite structure with corrugated-strip connectors (CSC) has the potential to be used in buildings and offshore structures. In this structure, CSCs are used to bond steel face plates and concrete. To overcome executive problems, in the proposed system by the authors, shear connectors are one end welded as double skin composites. Hence, this system double skin with corrugated-strip connectors (DSCS) is named. In this paper, finite element model (FEM) of push-out test was presented for the basic component of DSCS. ABAQUS/Explicit solver in ABAQUS was used due to the geometrical complexity of the model, especially in the interaction of the shear connectors with concrete. In order that the explicit analysis has a quasi-static behavior with a proper approximation, the kinetic energy (ALLKE) did not exceed 5% to 10% of the internal energy (ALLIE) using mass-scaling. The FE analysis (FEA) was validated against those from the push-out tests in the previous work of the authors published in this journal. By comparing load-slip curves and failure modes, FEMs with suitable analysis speed were consistent with test results.

Key Words
steel-concrete-steel sandwich; corrugated-strip connectors; push-out test; explicit analysis; mass-scaling

(1) Mehdi Yousefi:
Civil Engineering Department, Faculty of Maritime Engineering, Chabahar Maritime University, Chabahar, Iran;
(2) Mansour Ghalehnovi:
Civil Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.

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