• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.82-97
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• 1999

A deep sea vehicle must be designed to ensure its safety under ultra-high pressure circumstances. If a pressure housing of a deepsea vehicle is collapsed by ultra-high pressure, the deepsea vehicle may be lost. The objective of this paper is to introduce a design collapse pressure for the deep sea pressure vessel which is composed of one cylinder and two hemispheres. Especially the collapse pressure of hemispherical shell with a hole at top is analyzed by a variational approach (weighted residual method). And for the purpose of design, the salty factor of collapse pressure is presented which is analyzed by interpolation method.

• Structural Engineering and Mechanics
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• v.13 no.1
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• pp.35-52
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• 2002

It was shown in the previous study (Lee and Bertero 1993) that incremental collapse can lead to the exhaustion of the plastic rotation capacity at critical regions in a structure when subjected to the number of load cycles and load intensities as expected during maximum credible earthquakes and that this type of collapse can be predicted using the shakedown analysis technique. In this study, a minimum-weight design methodology, which takes into account not only the prevention of this incremental collapse but also the requirements of the serviceability limit states, is proposed by using the shakedown analysis technique and a nonlinear programming algorithm (gradient projection method).

• International Journal of Concrete Structures and Materials
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• v.6 no.4
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• pp.209-220
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• 2012

Post-earthquake fire (PEF) can lead to a rapid collapse of buildings that have been partially damaged as a result of a prior earthquake. Almost all standards and codes for the design of structures against earthquake ignore the risk of PEF, and thus buildings designed using those codes could be too weak when subjected to a fire after an earthquake. An investigation based on sequential analysis inspired by FEMA356 is performed here on the immediate occupancy (IO), life safety (LS) and collapse prevention (CP) performance levels of two portal frames, after they are pushed to arrive at a certain level of displacement corresponding to the mentioned performance level. This investigation is followed by a fire analysis of the damaged frames, examining the time taken for the damaged frames to collapse. As a point of reference, a fire analysis is also performed for undamaged frames and before the occurrence of earthquake. The results indicate that while there is minor difference between the fire resistances of the fire-alone situation and the frames pushed to the IO level of performance, a notable difference is observed between the fire-alone analysis and the frames pushed to arrive at LS and CP levels of performance and exposed to PEF. The results also show that exposing only the beams to fire results in a higher decline of the fire resistance, compared to exposing only the columns to fire. Furthermore, the results show that the frames pushed to arrive at LS and CP levels of performance collapse in a global collapse mode laterally, whereas at the IO level of performance and fire-alone situation, the collapse mechanism is mostly local through the collapse of beams. Whilst the investigation is conducted for a certain class of portal frames, the results confirm the need for the incorporation of PEF into the process of analysis and design, and provide some quantitative measures on the level of associated effects.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.155-160
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• 2003

For the weight reduction of vehicle body up to 20∼30% compared to the conventional monocoque steel body·.in-white, most automotive manufacturers have attempted to develop the aluminum intensive body-in-white using an aluminum space frame. In this paper, the crush tests and simulations for the aluminum extrusions filled with the structural from are performed to evaluate the collapse characteristics of that light weighted material. From these studies. the effectiveness of structural for is evaluated in improving automotive crashworthiness. In order to improve the improve energy absorption capability of the aluminum space frame body, safety design modifications are performed and analyzed based on the suggested collapse initiator concepts and on the application of the aluminum extrusions filled with structural foam. The effectiveness of these design concepts on the frontal and side impact characteristics of the aluminum intensive vehicle structure is investigated and summarized.

• Steel and Composite Structures
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• v.47 no.2
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• pp.253-267
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• 2023

The bearing capacities resisted by the two-bay beams of multi-story planar frames with unequal spans under column removal scenarios differ considerably owing to the asymmetric stress on the left and right beams connected to the failed column and cause the potential for beams with larger span-to-depth ratios to be unable to exert effectively, which is disadvantageous for resisting the vertical load in unequal-span frame structures. To address this problem, the structural measure of adding braces to the weak bays of multi-story unequal-span frames was proposed, with the objective of achieving a coordinated stress state in two-bay beams with unequal spans, thereby improving the collapse resistance of unequal-span frame structures. Before conducting the numerical simulation, the modeling methods were verified by previous experimental results of two multi-story planar frames with and without steel braces. Thereafter, the effects of the tensile and compressive braces on the collapse behavior of the frame structures were elucidated. Then, based on the mechanical action laws of the braces throughout the collapse process, a detailed design method for improving the collapse resistance of unequal-span frame structures was proposed. Finally, the proposed design method was verified by using sufficient example models, and the results demonstrated that the design method has good application prospects and high practical value.

• Steel and Composite Structures
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• v.14 no.4
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• pp.379-395
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• 2013

Aim of this paper is to apply to a steel truss bridge a methodology that takes into account the consequences of extreme loads on structures, focusing on the influence that the loss of primary elements has on the structural load bearing capacity. In this context, the topic of structural robustness, intended as the capacity of a structure to withstand damages without suffering disproportionate response to the triggering causes while maintaining an assigned level of performance, becomes relevant. In the first part of this study, a brief literature review of the topics of structural robustness, collapse resistance and progressive collapse takes place, focusing on steel structures. In the second part, a procedure for the evaluation of the structural response and robustness of skeletal structures under impact loads is presented and tested in simple structures. Following that, an application focuses on a case study bridge, the extensively studied I-35W Minneapolis steel truss bridge. The bridge, which had a structural design particularly sensitive to extreme loads, recently collapsed for a series of other reasons, in part still under investigation. The applied method aims, in addition to the robustness assessment, at increasing the collapse resistance of the structure by testing alternative designs.

• Advances in Computational Design
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• v.2 no.2
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• pp.121-131
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• 2017

Collapse was one of the typical common geological hazards during the construction of tunnels. The risk assessment of collapse was an effective way to ensure the safety of tunnels. We established a prediction model of collapse based on Bayesian Network. 76 large or medium collapses in China were analyzed. The variable set and range of the model were determined according to the statistics. A collapse prediction software was developed and its veracity was also evaluated. At last the software was used to predict tunnel collapses. It effectively evaded the disaster. Establishing the platform can be subsequent perfect. The platform can also be applied to the risk assessment of other tunnel engineering.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.653-669
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• 2016

Recent earthquakes worldwide show that a significant portion of the earthquake shaking happens in the vertical direction. This phenomenon has raised significant interests to consider the vertical ground motion during the seismic design and assessment of the structures. Strong vertical ground motions can alter the axial forces in the columns, which might affect the shear capacity of reinforced concrete (RC) members. This is particularly important for non-ductile RC frames, which are very vulnerable to earthquake-induced collapse. This paper presents the detailed nonlinear dynamic analysis to quantify the collapse risk of non-ductile RC frame structures with varying heights. An array of non-ductile RC frame architype buildings located in Los Angeles, California were designed according to the 1967 uniform building code. The seismic responses of the architype buildings subjected to concurrent horizontal and vertical ground motions were analyzed. A comprehensive array of ground motions was selected from the PEER NGA-WEST2 and Iran Strong Motions Network database. Detailed nonlinear dynamic analyses were performed to quantify the collapse fragility curves and collapse margin ratios (CMRs) of the architype buildings. The results show that the vertical ground motions have significant impact on both the local and global responses of non-ductile RC moment frames. Hence, it is crucial to include the combined vertical and horizontal shaking during the seismic design and assessment of non-ductile RC moment frames.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.132-139
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• 2004

The open section members have been used as the members of vehicle such as automotives, airplanes and trains. When vehicles are crashed, these members have absorption of the energy and it is necessary for retainment of the survival space, and as the result, the prediction for the displacement of members in this case of the crash of vehicles is very important. The displacements of members in this case of the crash of automotives show combined aspect of both axial collapse and bending collapse. In the rollover accident when bending collapse happen, the collapse of each members is progressed by the plastic hinge which made from bending moment, and therefore the research for the behavior of members under bending moment after collapse is necessary to determine the internal energy which the members can absorb and the deformed shapes of the members on the step of design. In this paper, the characteristics of bending collapse at the members of the open cross-section were studied with experiment and numerical analysis. We made a comparative studied of the result of the experiment, and changed the axis according to the parallel-axis theorem.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.163-172
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• 2014

The purpose of earthquake resistant design for typical bridges is the No Collapse Design and the Earthquake Resistant Design Part of Roadway Bridge Design Code provides a design process to construct the Ductile Failure Mechanism for the bridge structure. However, if it is not practical to provide the Ductile Failure Mechanism due to structure types or site conditions, the Brittle Failure Mechanism is an alternative way to get the No Collapse Design. As well as the existing design process constructing the Ductile Failure Mechanism, the Earthquake Resistant Design Part provides a ductility-based design process as an appendix, which is prepared for bridges with reinforced concrete piers. According to the new design process, designer determines a required response modification factor for substructure and transverse reinforcement for confinement therefrom. In this study, a typical bridge with steel bearing connections and reinforced concrete piers is selected for which the existing as well as the ductility-based design processes are applied and different results from the two design processes are identified. Based on the results, an earthquake resistant design procedure is proposed in which designers should consider the two design processes.