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CONTENTS
Volume 78, Number 4, May25 2021
 


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.

Key Words
porosities; dynamic stability; 3-unkonwn plate theory; nano-size plate; nonlocal elasticity

Address
Dong Wei: Engineering Research Center Heavy Machinery Ministry of Education, Taiyuan University of Science and Technology, Taiyuan 030024, Shanxi, China

Abstract
This paper provides a methodology to analyze the seismic performance of different component designs in hybrid masonry structures (HMS). HMS, comprised of masonry panels, steel frames and plate connectors is a relatively new structural system with potential applications in high seismic areas. HMS dissipate earthquake energy through yielding in the steel components and damage in the masonry panels. Currently, there are no complete codes to assist with the design of the energy dissipation components of HMS and there have been no computational studies performed to aid in the understanding of the system energy dissipation mechanisms. This paper presents parametric studies based on calibrated computational models to extrapolate the test data to a wider range of connector strengths and more varied reinforcement patterns and reinforcement ratios of the masonry panels. The results of the numerical studies are used to provide a methodology to examine the effect of connector strength and masonry panel design on the energy dissipation in HMS systems. We use as test cases two story structures subjected to cyclic loading due to the availability of experimental data for these configurations. The methodology presented is however general and can be applied to arbitrary panel geometries, and column and story numbers.

Key Words
hybrid masonry; energy dissipation; damage; yielding

Address
Zhenjia Gao, Mihaela Nistor and Ilinca Stanciulescu: Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA

Abstract
Ties are mandated by many design guidelines and codes to prevent the progressive collapse of buildings initiated by local failures. This study develops a model to estimate catenary/cable action capacity and the required ties in continuous reinforced concrete beams to bridge above the potential failed interior columns. The developed model is derived based on virtual work method and verified using test results presented in the literature. Also, parametric investigations are conducted to estimate the required ties in continuous reinforced concrete beams supporting one-way slab systems. A comparison is conducted between the estimated tie reinforcement using the developed model and that provided by satisfying the integrity provisions of the ACI 318-14 (2014) code. It is shown that the required tie reinforcements to prevent progressive collapse using the developed model are obviously larger than that provided by the integrity requirements of the ACI 318-14 (2014) code. It has been demonstrated that the increases in the demanded tie reinforcements over that provided by satisfying ACI 318-14 (2014) integrity provisions are varied between 1.01 and 1.46.

Key Words
integrity; tie reinforcements; reinforced concrete; progressive collapse; catenary action; virtual work

Address
Thaer M.S. Alrudaini: Department of Civil Engineering, Collage of Engineering, University of Basrah, Karmat Ali, Basrah, Iraq

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.

Key Words
high-speed railway; round-ended cross-sectional solid piers; seismic failure; shear strength model; cyclic loading test

Address
Wei Guo, Chao Fan: School of Civil Engineering, Central South University, Changsha 410075, China; National Engineering Laboratory for High-Speed Railway Construction, Changsha 410075, China
Yao Cui: State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China
Chen Zeng, Lizhong Jiang, Zhiwu Yu: School of Civil Engineering, Central South University, Changsha 410075, China; National Engineering Laboratory for High-Speed Railway Construction, Changsha 410075, China

Abstract
Under foundation shock mats have been used in the current practice in order to reduce/damp vibrations received by buildings through the surrounding environment. Although some investigations have been made on under foundation shock mats performance, their effectiveness in the reduction of railway induced-vibrations has not been fully studied, particularly with the consideration of underneath soil media. In this regard, this research is aimed at investigating performance of shock mat used beneath building foundation for reduction of railway induced-vibrations, taking into account soil-structure interaction. For this purpose, a 2D finite/infinite element model of a building and its surrounding soil media was developed. It includes an elastic soil media, a railway embankment, a shock mat, and the building. The model results were validated using an analytical solution reported in the literature. The performance of shock mats was examined by an extensive parametric analysis on the soil type, bedding modulus of shock mat and dominant excitation frequency. The results obtained indicated that although the shock mat can substantially reduce the building vibrations, its performance is significantly influenced by its underneath soil media. The softer the soil, the lower the shock mat efficiency. Also, as the train excitation frequency increases, a better performance of shock-mats is observed. A simplified model/method was developed for prediction of shock mat effectiveness in reduction of railway-induced vibrations, making use of the results obtained.

Key Words
vertical vibration; isolation method; soil-structure interaction; excitation frequency; shock mat

Address
Javad Sadeghi, Ehsan Haghighi and Morteza Esmaeili: School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran

Abstract
In this work, quasi three-dimensional (quasi-3D) shear deformation theory is presented for bending and dynamic analysis of functionally graded (FG) plates. The effect of varying material properties and volume fraction of the constituent on dynamic and bending behavior of the FG plate is discussed. The benefit of this model over other contributions is that a number of variables is diminished. The developed model considers nonlinear displacements through the thickness and ensures the free boundary conditions at top and bottom faces of the plate without using any shear correction factors. The basic equations that account for the effects of transverse and normal shear stresses are derived from Hamilton's principle. The analytical solutions are determined via the Navier procedure. The accuracy of the proposed formulation is proved by comparisons with the different 2D, 3D and quasi-3D solutions found in the literature.

Key Words
functionally graded plate; Quasi 3D HSDT; bending; vibration

Address
Bakhti Damani: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelkader Fekrar: Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Mahmoud M. Selim: Department of Mathematics, Al-Aflaj College of Science and Humanities, Prince Sattam bin Abdulaziz University, Al-Aflaj 710-11912, Saudi Arabia
Kouider Halim Benrahou: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelkader Benachour: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
E.A. Adda Bedia: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Muzamal Hussain: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan

Abstract
The present work focuses on experimental and numerical performance of the ferrocement RC walls reinforced with welded steel mesh, expanded steel mesh, fiber glass mesh and tensar mesh individually. The experimental program comprised twelve RC walls having the dimensions of 450 mmx100 mmx1000 mm under concentric compression loadings. The studied variables are the type of reinforcing materials, the number of mesh layers and volume fraction of reinforcement. The main aim is to assess the influence of engaging the new inventive materials in reinforcing the composite RC walls. Non-linear finite element analysis; (NLFEA) was carried out to simulate the behavior of the composite walls employing ANSYS-10.0 Software. Parametric study is also demonstrated to check out the variables that can mainly influence the mechanical behavior of the model such as the change of wall dimensions. The obtained numerical results indicated the acceptable accuracy of FE simulations in the estimation of experimental values. In addition, the strength gained of specimens reinforced with welded steel mesh was higher by amount 40% compared with those reinforced with expanded steel mesh. Ferrocement specimens tested under axial compression loadings exhibit superior ultimate loads and energy absorbing capacity compared to the conventional reinforced concrete one.

Key Words
ferrocement; RC walls; composite material; experimental; NLFE modeling; Ansys-10

Address
Yousry B.I. Shaheen: Civil Engineering Department, Faculty of Engineering, Menoufia University, Menoufia, Egypt
Hala M. Refat: Civil Engineering Department, Faculty of Engineering, Benha University, Benha, Egypt
Ashraf M. Mahmoud: Civil Engineering Department, Faculty of Engineering, Modern University for Technology and Information (MTI), Al-Mokattam, Cairo, Egypt

Abstract
Similar to other structures, ultimate strength values showing the maximum load that the structure can resist without damaging has great importance on ships. Therefore, increasing the ultimate strength values will be an important benefit for the structure. Low carbon steels used in ships due to their low cost and good weldability. Improving the ultimate strength values without interfering with the chemical composition to prevent of the weldability properties of these steels would be very beneficial for ships. Grain refinement via severe plastic deformation (SPD) is an essential strengthening mechanism without changing the chemical composition of metallic materials. Among SPD methods, equal channel angular pressing (ECAP) is one of the most commonly used one due to its capacity for achieving bulk ultrafine-grained (UFG) materials. When the literature is examined, it is seen that there is no study about ultimate strength calculation in ships after ECAP. Therefore, the mean purpose of this study is to apply ECAP to a shipbuilding low carbon steel to be able to achieve mechanical properties and investigate the alteration of ship hull girder grillage system's ultimate strength via finite element analysis approach. A fine-grained (FG) microstructure with a mean grain size of 6 um (initial grain size was 25 um) was after ECAP. This microstructural evolution brought about a considerable increase in strength values. Both yield and tensile strength values increased from 280 MPa and 425 MPa to about 420 MPa and 785 MPa, respectively. This improvement in the strength values reflected a finite element method to determine the ultimate strength of ship hull girder grillage system. As a result of calculations, it was reached significantly higher ultimate strength values (237,876 MPa) compared the non-processed situation (192,986 MPa) on ship hull girder grillage system.

Key Words
low carbon shipbuilding steel; equal channel angular pressing; ultimate strength; finite element analysis approach

Address
Dursun Murat Sekban and Hasan Olmez: Department of Marine Engineering Operations, Karadeniz Technical University, Trabzon-Turkey

Abstract
So far analytical methods on collapse assessment of three-dimensional (3-D) steel frames have mainly focused on a single-column-removal scenario. However, the collapse of the Federal Building in the US due to car bomb explosion indicated that the loss of multiple columns may occur in the real structures, wherein the structures are more vulnerable to collapse. Meanwhile, the General Services Administration (GSA) in the US suggested that the removal of side columns of the structure has a great possibility to cause collapse. Therefore, this paper analytically deals with the robustness of 3-D steel frames in a twoside- column-removal (TSCR) scenario. Analytical method is first proposed to determine the collapse resistance of the frame during this column-removal procedure. The reliability of the analytical method is verified by the finite element results. Moreover, a design-based methodology is proposed to quickly assess the robustness of the frame due to a TSCR scenario. It is found the analytical method can reasonably predict the resistance-displacement relationship of the frame in the TSCR scenario, with an error generally less than 10%. The parametric numerical analyses suggest that the slab thickness mainly affects the plastic bearing capacity of the frame. The rebar diameter mainly affects the capacity of the frame at large displacement. However, the steel beam section height affects both the plastic and ultimate bearing capacity of the frame. A case study on a sixstorey steel frame shows that the design-based methodology provides a conservative prediction on the robustness of the frame.

Key Words
multi-column-removal; robustness; assessment; analytical method; design approach

Address
JingZhou Zhang: Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China
Michael C.H. Yam: Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China; The Chinese National Engineering Research Center (CNERC), Hong Kong, China
Ghazaleh Soltanieh: The Chinese National Engineering Research Center (CNERC), Hong Kong, China
Ran Feng: School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen, China

Abstract
In this study, a new method for treating the wall boundary in smoothed particle hydrodynamics (SPH) is proposed to simulate free surface flows effectively. Unlike conventional methods of wall boundary treatment through boundary particles, in the proposed method, the wall boundary condition is directly imposed by adding boundary truncation terms to the mass and momentum conservation equations. Thus, boundary particles are not used in boundary modeling. Doing so, the wall boundary condition is accurately imposed, boundary modeling is simplified, and computation is made efficient without losing stability in SPH. Performance of the proposed method is demonstrated through several numerical examples: dam break, dam break with a wedge, sloshing, inclined bed, cross-lever rotation, pulsating tank and sloshing with a flexible baffle. These results are compared with available experimental results, analytical solutions, and results obtained using the boundary particle method.

Key Words
smoothed particle hydrodynamics; SPH; hydrodynamics; wall boundary; free surface flow; boundary modeling; fluid–structure interaction

Address
Hyung-Jun Park, Hyun-Duk Seo and Phill-Seung Lee: Department of Mechanical Engineering, Korean Advanced Institute for Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea


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