• Structural Engineering and Mechanics
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• v.75 no.6
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• pp.771-784
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• 2020

Reliability analysis techniques combining with various surrogate models have attracted increasing attention because of their accuracy and great efficiency. However, they primarily focus on the structures with continuous response, while very rare researches on the reliability analysis for structures with discontinuous response are carried out. Furthermore, existing adaptive reliability analysis methods based on importance sampling (IS) still have some intractable defects when dealing with small failure probability, and there is no related research on reliability analysis for structures involving discontinuous response and small failure probability. Therefore, this paper proposes a novel reliability analysis method called AGPC-IS for such structures, which combines adaptive Gaussian process classification (GPC) and adaptive-kernel-density-estimation-based IS. In AGPC-IS, an efficient adaptive strategy for design of experiments (DoE), taking into consideration the classification uncertainty, the sampling uniformity and the regional classification accuracy improvement, is developed with the purpose of improving the accuracy of Gaussian process classifier. The adaptive kernel density estimation is introduced for constructing the quasi-optimal density function of IS. In addition, a novel and more precise stopping criterion is also developed from the perspective of the stability of failure probability estimation. The efficiency, superiority and practicability of AGPC-IS are verified by three examples.

• Wind and Structures
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• v.36 no.2
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• pp.133-147
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• 2023

The random vibration of saddle membrane structures under wind load is studied theoretically and experimentally. First, the nonlinear random vibration differential equations of saddle membrane structures under wind loads are established based on von Karman's large deflection theory, thin shell theory and potential flow theory. The probabilistic density function (PDF) and its corresponding statistical parameters of the displacement response of membrane structure are obtained by using the diffusion process theory and the Fokker Planck Kolmogorov equation method (FPK) to solve the equation. Furthermore, a wind tunnel test is carried out to obtain the displacement time history data of the test model under wind load, and the statistical characteristics of the displacement time history of the prototype model are obtained by similarity theory and probability statistics method. Finally, the rationality of the theoretical model is verified by comparing the experimental model with the theoretical model. The results show that the theoretical model agrees with the experimental model, and the random vibration response can be effectively reduced by increasing the initial pretension force and the rise-span ratio within a certain range. The research methods can provide a theoretical reference for the random vibration of the membrane structure, and also be the foundation of structural reliability of membrane structure based on wind-induced response.

• International Journal of High-Rise Buildings
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• v.12 no.3
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• pp.203-208
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• 2023

The implementation of artificial intelligence (AI) design for tall building structures is an essential solution for addressing critical challenges in the current structural design industry. Generative AI technology is a crucial technical aid because it can acquire knowledge of design principles from multiple sources, such as architectural and structural design data, empirical knowledge, and mechanical principles. This paper presents a set of AI design techniques for building structures based on two types of generative AI: generative adversarial networks and graph neural networks. Specifically, these techniques effectively master the design of vertical and horizontal component layouts as well as the cross-sectional size of components in reinforced concrete shear walls and frame structures of tall buildings. Consequently, these approaches enable the development of high-quality and high-efficiency AI designs for building structures.

• Earthquakes and Structures
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• v.4 no.4
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• pp.341-363
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• 2013

Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

• Computers and Concrete
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• v.17 no.2
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• pp.173-188
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• 2016

Generally, thermal stress induced by hydration heat causes cracking in mass concrete structures, requiring a thorough control during the construction. The prediction of the thermal stress is currently undertaken by means of numerical analysis despite its lack of reliability due to the properties of concrete varying over time. In this paper, a method for the prediction of thermal stress in concrete structures by adjusting thermal stress measured by a thermal stress device according to the degree of restraint is proposed to improve the prediction accuracy. The ratio of stress in concrete structures to stress under complete restraint is used as the degree of restraint. To consider the history of the degree of restraint, incremental stress is predicted by comparing the degree of restraint and the incremental stress obtained by the thermal stress device. Furthermore, the thermal stresses of wall and foundation predicted by the proposed method are compared to those obtained by numerical analysis. The thermal stresses obtained by the proposed method are similar to those obtained by the analysis for structures with internally as well as externally strong restraint. It is therefore concluded that the prediction of thermal stress for concrete structures with various boundary conditions using the proposed method is suggested to be accurate.

• Steel and Composite Structures
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• v.15 no.5
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• pp.539-566
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• 2013

This paper summarises the results of a numerical study on the non linear response of steel concentric braced frames under monotonic and cyclic loads, using force-based finite elements with section fibre discretisation. The first part of the study is addressed to analyse the single brace response. A parametric analysis was carried out and discussed to evaluate the accuracy of the model, examining the influence of the initial camber, the material modelling, the type of force-based element, the number of integration points and the number of fibers. The second part of the paper is concerned with the modelling issues of whole braced structures. The effectiveness of the modelling approach is verified against the nonlinear static and dynamic behaviour of different type of bracing configurations. The model sensitivity to brace-to-brace interaction and the capability of the model to mimic the response of complex bracing systems is analyzed. The influence of different approaches for modelling the inertia, the equivalent viscous damping and the brace hysteretic response on the overall structural response are also investigated. Finally, on the basis of the performed numerical study general modelling recommendations are proposed.

• Journal of Korean Association for Spatial Structures
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• v.14 no.3
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• pp.101-108
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• 2014

Recently, natural disasters such as earthquake, tsunami, typhoon and tornado are increasing, and cause huge economical loses and victim. Thus, when the disaster occurs, it is important to prepare emergency evacuation shelters for fast and easy construction compared to general building system. And, deployable structures will provide a great help for such aim. Deployable structures have the great advantage of being faster and easier to erect and dismantle compared to conventional building forms. In this study, we confirm the possibility of deployment for shelter structures using scissor structure system. First, Basic model was performed to recognize the appllicability of the deployable systems of the dome-shaped structure. Second, Advanced model that more improved inner space and deployment mechanism was confirmed.

• Computers and Concrete
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• v.21 no.1
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• pp.55-66
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• 2018

A large main shock may consist of numerous aftershocks with a short period. The aftershocks induced by a large main shock can cause the collapse of a structure that has been already damaged by the preceding main shock. These aftershocks are important factors in structural damages. Furthermore, despite what is often assumed in seismic design codes, earthquakes do not usually occur as a single event, but as a series of strong aftershocks and even fore shocks. For this reason, this study investigates the effect and potential of consecutive earthquakes on the response and behavior of concrete structures. At first, six moment resisting concrete frames with 3, 5, 7, 10, 12 and 15 stories are designed and analyzed under two different records with seismic sequences from real and artificial cases. The damage states of the model frames were then measured by the Park and Ang's damage index. From the results of this investigation, it is observed that the sequences of ground motions can almost double the accumulated damage and increased response of structures. Therefore, it is certainly insufficient to ignore this effect in the design procedure of structures. Also, the use of artificial seismic sequences as design earthquake can lead to non-conservative prediction of behavior and damage of structures under real seismic sequences.

• Journal of Ocean Engineering and Technology
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• v.19 no.2 s.63
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• pp.34-39
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• 2005

All of the design criterion are not only formulated by an internal study, concerning the design of maritime structures, but also by the guarantee that internal design technology is essential, at least according to theoretical and experimental studies. Furthermore, the basic data, which is necessary for the development of a more stable design of breakwater structures, should be ensured, according to current research and analysis of damage created by water waves. According to the necessity to solve the problems that occur in the design and construction of ocean structures, until now, it is recognized that the hydraulic experiments are important. This paper provides the design of structures to decrease the energy created by waves. Suggestions to make contributions to the development of ocean/fisheries technology are also discussed. It is better to use S-type coastal structures/breakwaters than to use uniform type breakwaters, concerning stability, reflection, and overtopping.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1327-1332
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• 2014

This paper presents information about the examples of the design on Illumination of Structures(LED Light Pipe for lighthouse) in Korea. We have applied illumination by flood-lighting or facade-lighting in place of the 57 lighthouses (offshore structures) and 4 beacons. The ways of illumination of structures are using direct illumination with LED, halogen lamps and metal halide lamps, and indirect illumination with LED non-neon lamps. The illumination of structures helps a observer to identify the Aids to Navigation and w aterway. The fabricated LED Light Pipe is a transparent acrylic round bar and easy to install. The Light Pipe is arranged in two rows of L ED (78ea). It can be connected in series. It has 4 colours(Red, Green, Yellow, White). We analyzed and the horizontal divergence angle of the LED light pipe is defined as the range with 50% of maximum luminous intensity. Also, we evaluated the conspicuity on the origin al lantern and LED Light pipe for lighthouse. The field experiment was conducted in 'Yeosuguhang lighthouse' in Yeosu-city (Korea). F rom the experimental results, it was confirmed that the fabricated LED Light Pipe is clearly distinguished.