|
Sustainability of steel structures: towards an integrated approach to life-time engineering design
Raffaele LANDOLFO, Lucrezia CASCINI, Francesco PORTIOLI
Front Arch Civil Eng Chin. 2011, 5 (3): 304-314.
https://doi.org/10.1007/s01709-011-0123-9
Nowadays, the construction sector is more and more oriented toward the promotion of sustainability in all its activities. The goal to achieve is the optimization of performances, over the whole life-cycle, with respect to environmental, economic and social requirements. According to the latest advances, the concept of sustainability applied to constructions covers a number of branches such as life-cycle costing, ecology, durability and even structural design. Several procedures and design tools have been implemented in the framework of international research. Indeed the current trend in civil engineering research is moving towards life-time engineering, with the aim to implement integrated methodologies to consider as a whole all the sustainability requirements according to time-dependent multi-performance-based design approaches. Following a general introduction of the concept of sustainability applied to constructions, this paper presents an overview of life-time engineering methodologies according to the current state-of-the-art. In particular the methods currently received by International Standards are discussed. A special focus is devoted to the durability design of metal structures with respect to the degradation phenomena able to impair the structural capacity over time. Finally a proposal towards an integrated approach to life-time engineering design of steel structures and needs for further advances are presented.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Estimation of load and resistance factors using the third-moment method based on the 3P-lognormal distribution
Yan-Gang ZHAO, Zhao-Hui LU
Front Arch Civil Eng Chin. 2011, 5 (3): 315-322.
https://doi.org/10.1007/s11709-011-0117-7
Load and resistance factors are generally obtained using the first order reliability method (FORM) in which the design point should be determined and derivative-based iterations used. In this article, the third-moment reliability index, based on the three-parameter lognormal (3P-lognormal) distribution, is investigated. A simple method based on the third-moment method for estimating load and resistance factors is then proposed, and a simple formula for the target mean resistance is also presented to avoid iterative computations. Unlike the currently used method, the proposed method can be used to determine load and resistance factors, even when the probability density functions (PDFs) of the basic random variables are not available. Moreover, the proposed method does not require the iterative computation of derivatives or any design points. Thus, the method provides a more convenient and effective way to estimate load and resistance factors in practical engineering applications. Numerical examples are presented to demonstrate the advantages of the proposed third moment method for determining load and resistance factors.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Seismic tests of post-tensioned self-centering building frames with column and slab restraints
Chung-Che CHOU, Jun-Hen CHEN
Front Arch Civil Eng Chin. 2011, 5 (3): 323-334.
https://doi.org/10.1007/s11709-011-0119-5
Post-tensioned (PT) self-centering moment frames have been developed as an alternative to typical moment-resisting frames (MRFs) for earthquake resistance. When a PT frame deforms laterally, gaps between the beams and columns open. However, the gaps are constrained by the columns and the slab in a real PT self-centering building frame. This paper presents a methodology for evaluating the column restraint and beam compression force based on the column deformation and gap openings at all stories. The method is verified by cyclic tests of a full-scale, two-bay by one-story PT frame. Moreover, a sliding slab is proposed to minimize restraints on the expansion of the PT frame. Shaking table tests were conducted on a reduced-scale, two-by-two bay one-story specimen, which comprises one PT frame and two gravitational frames. The PT frame and gravitational frames are self-centering throughout the tests, responding in phase with only minor differences in peak drifts caused by expansion of the PT frame. When the specimen is excited by a simulation of the 1999 Chi-Chi earthquake with a peak ground acceleration of 1.87 g, the maximum interstory drift and the residual drift are 7.2% and 0.01%, respectively.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Static behavior of planar intersecting CFST connection in diagrid structure
Ling LI, Xianzhong ZHAO, Ke KE
Front Arch Civil Eng Chin. 2011, 5 (3): 355-365.
https://doi.org/10.1007/s11709-011-0125-7
Intersecting connection plays an important role in the new diagrid structural system for high-rise buildings. To investigate the static behavior of the intersecting connection of concrete-filled steel tubular (CFST) columns, a typical reduced-scale planner connection specimen is tested under monotonic axial compression. The failure modes, force mechanism and bearing capacity of intersecting CFST connections are analyzed further in the follow-up numerical simulation, considering influences of intersecting angle, elliptical plate and ring plate. Test and simulation results prove that, intersecting connection can develop fully plastic deformation and provide sufficient bearing capacity. Parametric analysis indicates that bearing capacity of planar intersecting CFST connection mainly depends on intersecting angle and thickness of elliptical plate, while the ring plate affects that little. Capacity estimation method for planar intersecting CFST connection is proposed basing on the capacity of the critical section which is located near intersecting center for a distance of steel tube radius, and the design suggestions is provided in the end of this paper.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Unified calculation method and its application in determining the uniaxial mechanical properties of concrete
Faxing DING, Xiaoyong YING, Linchao ZHOU, Zhiwu YU
Front Arch Civil Eng Chin. 2011, 5 (3): 381-393.
https://doi.org/10.1007/s11709-011-0118-6
This paper presents a unified calculation method and its application in determining the uniaxial mechanical properties of concrete with concrete strengths ranging from 10 to 140 MPa. By analyzing a large collection of test results of the uniaxial mechanical properties of normal-strength, high-strength and super high-strength concrete in China and performing a regression analysis, unified calculation formulas for the mechanical indexes of concrete are proposed that can be applied to various grades of concrete for determining the size coefficient, uniaxial compressive strength, uniaxial tensile strength, elastic modulus, and strain at peak uniaxial compression and tension. Optimized mathematical equations for the nonlinear stress-strain relationship of concrete, including the ascending and descending branches under uniaxial stress, are also established. The elastic modulus is almost constant throughout the elastic stage for the ascending branches of the stress-strain relationship for concrete. The proposed stress-strain relationship of concrete was applied to the nonlinear finite element analysis of both a steel-concrete composite beam and a concrete-filled steel tubular stub column. The analytical results are in good agreement with the experiment results, indicating that the proposed stress-strain relationship of concrete is applicable. The achievements presented in this paper can be used as references for the design and nonlinear finite element analysis of concrete structures.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Seismic analysis of a super high-rise steel structure with horizontal strengthened storeys
Yuanqing WANG, Hui ZHOU, Yongjiu SHI, Yi HUANG, Gang SHI, Siqing WEN
Front Arch Civil Eng Chin. 2011, 5 (3): 394-404.
https://doi.org/10.1007/s11709-011-0116-8
Horizontal strengthened storeys are widely used in super high-rise steel structures to improve the lateral structural rigidity. This use has great effects on the seismic properties of the entire structure. The seismic properties of the Wuhan International Securities Building (a 68-storey super high-rise steel structure with three horizontal strengthened storeys) were evaluated in this study. Two approaches, i.e., mode-superposition response spectrum analysis and time-history analysis, were employed to calculate the seismic response of the structure. The response spectrum analysis indicated that transition parts near the three strengthened storeys were weak zones of the structure because of the abrupt change in rigidity. In the response spectrum analysis approach, the Square Root of Sum of Square (SRSS) method was recommended when the vertical seismic effects could be ignored. However, the complete quadratic combination (CQC) method was superior to SRSS method when the vertical seismic effects should be considered. With the aid of time-history analysis, the seismic responses of the structure were obtained. The whiplash effect that spectrum analysis cannot reveal was observed through time-history analysis. This study provides references for the seismic design of super high-rise steel structures with horizontal strengthened storeys.
Figures and Tables |
References |
Related Articles |
Metrics
|
15 articles
|