![]() | |
CONTENTS | |
Volume 13, Number 5, November 2017 |
|
- Effect of thermal regime on the seismic response of a dry bridge in a permafrost region along the Qinghai-Tibet Railway Xiyin Zhang, Mingyi Zhang, Xingchong Chen, Shuangyang Li and Fujun Niu
| ||
Abstract; Full Text (1994K) . | pages 429-442. | DOI: 10.12989/eas.2017.13.5.429 |
Abstract
Dry bridges have been widely applied in the Qinghai-Tibet Railway (QTR) to minimize the thermal disturbance of engineering to the permafrost. However, because the Qinghai-Tibet Plateau is an area with a high potential occurrence of earthquakes, seismic action can easily destroy the dry bridges. Therefore, a three-dimensional numerical model, with consideration of the soil-pile interactions, is established to investigate the thermal characteristics and their impact on the seismic response of the dry bridge in permafrost region along the QTR. The numerical results indicate that there exist significant differences in the lateral displacement, shear force, and bending moment of the piles in different thermal conditions under seismic action. When the active layer become from unfrozen to frozen state, the maximum displacement of the bridge pile reduces, and the locations of the zero and peak values of the shear force and bending moment also change. It is found that although the higher stiffness of frozen soil confines the lateral displacement of the pile, compared with unfrozen soil, it has an adverse effect on the earthquake energy dissipation capacity.
Key Words
numerical analysis; dry bridge; thermal characteristics; soil-pile interaction; seismic response; permafrost region
Address
Xiyin Zhang: State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
Mingyi Zhang: State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
Xingchong Chen: School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
Shuangyang Li and Fujun Niu: State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences, Lanzhou 730000, China
- Performance-based seismic design of eccentrically braced steel frames using target drift and failure mode Shen Li, Jian-bo Tian and Yun-he Liu
| ||
Abstract; Full Text (1933K) . | pages 443-454. | DOI: 10.12989/eas.2017.13.5.443 |
Abstract
When eccentrically braced steel frames (EBFs) are in the desired failure mode, links yield at each layer and column bases appear plastically hinged. Traditional design methods cannot accurately predict the inelastic behavior of structures owing to the use of capacity-based design theory. This paper proposes the use of performance-based seismic design (PBSD) method for planning eccentrically braced frames. PBSD can predict and control inelastic deformation of structures by target drift and failure mode. In buildings designed via this process, all links dissipate energy in the rare event of an earthquake, while other members remain in elastic state, and as the story drift is uniform along the structure height, weak layers will be avoided. In this condition, eccentrically braced frames may be more easily rehabilitated after the effects of an earthquake. The effectiveness of the proposed method is illustrated through a sample case study of ten-story K-type EBFs and Y- type EBFs buildings, and is validated by pushover analysis and dynamic analysis. The ultimate state of frames designed by the proposed method will fail in
the desired failure mode. That is, inelastic deformation of structure mainly occurs in links; each layer of links involved dissipates energy, and weak layers do not exist in the structure. The PBSD method can provide a reference for structural design of eccentrically braced steel frames.
Key Words
performance-based seismic design; eccentrically braced steel frames; failure mode; link; weak layer
Address
Shen Li, Jian-bo Tian and Yun-he Liu: School of Civil Engineering and architecture, Xi\'an University of Technology, Xi\'an Beilin District Jinhua Road No. 5, 710048, P. R. China
- An ESED method for investigating seismic behavior of single-layer spherical reticulated shells Ming Zhang, Guangchun Zhou, Yanxia Huang, Xudong Zhi and De-Yi Zhang
| ||
Abstract; Full Text (1808K) . | pages 455-464. | DOI: 10.12989/eas.2017.13.5.455 |
Abstract
This paper develops a new method for analyzing the structural seismic behavior of single-layer reticulated shells based on exponential strain energy density (ESED). The ESED method reveals a characteristic point from a relationship between ESED sum and peak seismic acceleration. Then, the characteristic point leads to an updated concept of structural failure and an
ESED-based criterion for predicting structural failure load. Subsequently, the ESED-based criterion and the characteristic point are verified through numerical analysis of typical single-layer reticulated shells with different configurations and a shaking table test of the scale shell model. Finally, discussions further verify the rationality and application of the ESED-based criterion. The ESED method might open a new way of structural analysis and the ESED-based criterion might indicate a prospect for a unified criterion for predicting seismic failure loads of various structures.
Key Words
ESED method; ESED-based criterion; failure load; single-layer spherical shell; characteristic point
Address
Ming Zhang: School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China
Guangchun Zhou: School of Civil Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China
Yanxia Huang: School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China
Xudong Zhi: School of Civil Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China
De-Yi Zhang: School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China
- Fractional wave propagation in radially vibrating non-classical cylinder Odunayo O. Fadodun, Olawanle P. Layeni and Adegbola P. Akinola
| ||
Abstract; Full Text (1310K) . | pages 465-471. | DOI: 10.12989/eas.2017.13.5.465 |
Abstract
This work derives a generalized time fractional differential equation governing wave propagation in a radially vibrating non-classical cylindrical medium. The cylinder is made of a transversely isotropic hyperelastic John\'s material which obeys frequency-dependent power law attenuation. Employing the definition of the conformable fractional derivative, the solution of the obtained generalized time fractional wave equation is expressed in terms of product of Bessel functions in spatial and temporal variables; and the resulting wave is characterized by the presence of peakons, the appearance of which fade in density as the order of fractional derivative approaches 2. It is obtained that the transversely isotropic structure of the material of the cylinder increases the wave speed and introduces an additional term in the wave equation. Further, it is observed that the law relating the non-zero components of the Cauchy stress tensor in the cylinder under consideration generalizes the hypothesis of plane strain in classical elasticity theory. This study reinforces the view that fractional derivative is suitable for modeling anomalous wave propagation in media.
Key Words
fractional wave; non-classical cylinder; radial vibration
Address
Odunayo O. Fadodun, Olawanle P. Layeni and Adegbola P. Akinola: Department of Mathematics, Obafemi Awolowo University, Ile-Ife, 220005, Nigeria
- Seismic upgrading of reinforced concrete frames with steel plate shear walls Hasan H. Korkmaz and Ali S. Ecemis
| ||
Abstract; Full Text (5801K) . | pages 473-484. | DOI: 10.12989/eas.2017.13.5.473 |
Abstract
The objective of this paper is to report on a study of the use of unstiffened thin steel plate shear walls (SPSWs) for the seismic performance improvement of reinforced concrete frames with deficient lateral rigidity. The behaviour of reinforced concrete frames during seismic activities was rehabilitated with an alternative and occupant-friendly retrofitting scheme. The study involved tests of eight 1/3 scale, one bay, two storey test specimens under cyclic quasi-static lateral loadings. The first specimen, tested in previous test program, was a reference specimen, and in seven other specimens, steel infill plates were used to replace the conventional infill brick or the concrete panels. The identification of the load-deformation characteristics, the determination of the level of improvement in the overall strength, and the elastic post-buckling stiffness were the main issues investigated during the quasi-static test program. With the introduction of the SPSWs, it was observed that the strength, stiffness and energy absorption capacities were significantly improved. It was also observed that the experimental hysteresis curves were stable, and the composite systems showed excellent energy dissipation capacities due to the formation of a diagonal tension field action along with a diagonal compression buckling of the infill plates.
Key Words
steel plate; lateral rigidity; earthquake; rehabilitation; reinforced concrete frame
Address
Hasan H. Korkmaz and Ali S. Ecemis: Engineering Faculty, Civil Engineering Department, Selcuk University, Konya, Turkey
- Experimental investigation of SRHSC columns under biaxial loading Peng Wang, Qing X. Shi, Feng Wang and Qiu W. Wang
| ||
Abstract; Full Text (3935K) . | pages 485-496. | DOI: 10.12989/eas.2017.13.5.485 |
Abstract
The behavior of 8 steel reinforced high-strength concrete (SRHSC) columns, which comprised of four identical columns with cross-shaped steel and other four identical columns with square steel tube, was investigated experimentally under cyclic uniaxial and biaxial loading independently. The influence of steel configuration and loading path on the global behavior of SRHSC columns in terms of failure process, hysteretic characteristics, stiffness degradation and ductility were investigated and discussed, as well as stress level of the longitudinal and transverse reinforcing bars and steel. The research results indicate that with a same steel ratio deformation capacity of steel reinforced concrete columns with a square steel tube is better than the one with a cross-shaped steel. Loading path affects hysteretic characteristics of the specimens significantly. Under asymmetrical loading path, hysteretic characteristics of the specimens are also asymmetry. Compared with specimens under unidirectional loading, specimens subjected to bidirectional loading have poor carrying capacity, fast stiffness degradation, small yielding displacement, poor ductility and small ultimate failure drift. It also demonstrates that loading paths affect the deformation
capacity or deformation performance significantly. Longitudinal reinforcement yielding occurs before the peak load is attained, while steel yielding occurs at the peak load. During later displacement loading, strain of longitudinal and transverse reinforcing bars and steel of specimens under biaxial loading increased faster than those of specimens subjected to unidirectional loading. Therefore, the bidirectional loading path has great influence on the seismic performance such as carrying capacity and deformation performance, which should be paid more attentions in structure design.
Key Words
steel reinforced concrete columns; high-strength concrete; bidirectional loading; coupling effect; seismic behavior
Address
Peng Wang, Qing X. Shi, Feng Wang and Qiu W. Wang: School of Civil Engineering, Xi\'an University of Architecture & Technology, No.13, Yanta Road, Xi\'an, Shaanxi, China
- Applied methods for seismic assessment of scoured bridges: a review with case studies Xuan Guo, Mostafa Badroddin and ZhiQiang Chen
| ||
Abstract; Full Text (1686K) . | pages 497-507. | DOI: 10.12989/eas.2017.13.5.497 |
Abstract
Flooding induced scour has been long recognized as a major hazard to river-crossing bridges. Many studies in
recent years have attempted to evaluate the effects of scour on the seismic performance of bridges, and probabilistic frameworks are usually adopted. However, direct and straightforward insight about how foundation scour affects bridges as a type of soil-foundation-structure system is usually understated. In this paper, we provide a comprehensive review of applied methods
centering around seismic assessment of scoured bridges considering soil-foundation-structure interaction. When introducing these applied analysis and modeling methods, a simple bridge model is provided to demonstrate the use of these methods as a case study. Particularly, we propose the use of nonlinear modal pushover analysis as a rapid technique to model scoured bridge systems, and numerical validation and application of this procedure are given using the simple bridge model. All methods reviewed in this paper can serve as baseline components for performing probabilistic vulnerability or risk assessment for any
river-crossing bridge system subject to flood-induced scour and earthquakes.
Key Words
bridge scour; multi-hazard analysis; soil-foundation-structure interaction; foundation impedance; seismic
effects; nonlinear modal pushover analysis
Address
Xuan Guo: Department of Civil Engineering, Yangzhou University, Yangzhou, China
Mostafa Badroddin and ZhiQiang Chen: Department of Civil and Mechanical Engineering, University of Missouri-Kansas City, Missouri, USA
- A simple quasi-3D sinusoidal shear deformation theory with stretching effect for carbon nanotube-reinforced composite beams resting on elastic foundation Lazreg Hadji, Nafissa Zouatnia, Mohamed Ait Amar Meziane and Amar Kassoul
| ||
Abstract; Full Text (1133K) . | pages 509-518. | DOI: 10.12989/eas.2017.13.5.509 |
Abstract
The objective of the present paper is to investigate the bending behavior with stretching effect of carbon nanotubereinforced composite (CNTRC) beams. The beams resting on the Pasternak elastic foundation, including a shear layer and Winkler spring, are considered. The single-walled carbon nanotubes (SWCNTs) are aligned and distributed in polymeric matrix with different patterns of reinforcement. The material properties of the CNTRC beams are estimated by using the rule of mixture. The significant feature of this model is that, in addition to including the shear deformation effect and stretching effect it deals with only 4 unknowns without including a shear correction factor. The single-walled carbon nanotubes (SWCNTs) are aligned and distributed in polymeric matrix with different patterns of reinforcement. The material properties of the CNTRC beams are assessed by employing the rule of mixture. The equilibrium equations have been obtained using the principle of virtual displacements. The mathematical models provided in this paper are numerically validated by comparison with some available results. New results of bending analyses of CNTRC beams based on the present theory with stretching effect is presented and discussed in details. the effects of different parameters of the beam on the bending responses of CNTRC beam are discussed.
Key Words
bending; stretching effect; CNTRC beams; elastic foundation
Address
Lazreg Hadji: Department of Civil Engineering, Ibn Khaldoun University, BP 78 Zaaroura, 14000 Tiaret, Algeria; Laboratory of Geomatics and Sustainable Development, Ibn Khaldoun University of Tiaret, Algeria
Nafissa Zouatnia: Department of Civil Engineering, Laboratory of Structures, Geotechnics and Risks (LSGR), Hassiba Benbouali University of Chlef, Algeria, BP 151, Hay Essalam, UHB Chlef, Chlef (02000), Algeria
Mohamed Ait Amar Meziane: Department of Civil Engineering, Ibn Khaldoun University, BP 78 Zaaroura, 14000 Tiaret, Algeria
Amar Kassoul: Department of Civil Engineering, Laboratory of Structures, Geotechnics and Risks (LSGR), Hassiba Benbouali University of Chlef, Algeria, BP 151, Hay Essalam, UHB Chlef, Chlef (02000), Algeria