• Structural Engineering and Mechanics
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• v.71 no.2
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• pp.131-138
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• 2019

It is necessary to predict subway induced vibration if a new subway is to be built. To obtain the vibration response reliably, a three-dimensional (3D) FEM model, consisting of the tunnel, the soil, the subway load and the building above, is established in MIDAS GTS NX. For this study, it is a six-story frame structure built above line 3 of Guangzhou metro. The entire modeling process is described in detail, including the simplification of the carriage load and the determination of model parameters. Vibration measurements have been performed on the site of the building and the model is verified with the collected data. The predicted and measured vibration response are used together to assess vibration level due to the subway traffic in the building. The No.1 building can meet work and residence comfort requirement. This study demonstrates the applicability of the numerical train-tunnel-soil-structure model for the serviceability assessment of subway induced vibration and aims to provide practical references for engineering applications.

• Advances in concrete construction
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• v.16 no.4
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• pp.217-230
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• 2023

Methods for designing the post-tensioned anchorage zones at ultimate limit state has been specified in current design codes based on strut-and-tie models (STM). However, it is still not clear how to estimate the serviceability behavior of the anchorage zones. The serviceability is just indirectly taken into account by means of the reasonable reinforcement detailing. To address this issue, this paper is devoted to developing a modified strut-and-tie model (MSTM) to predict the behavior of concentric anchorage zones throughout the loading process. The principle of stationary complementary energy is introduced into STM at each load step to satisfy the compatibility condition and generate the unique MSTM. The structural behavior of anchorage zones can be achieved based on MSTM from loading to failure. Simplified formulas have been proposed to estimate the first cracking load, bearing capacity and maximum crack width with the consideration of the details of reinforcement bursting bars. The proposed model provides a definite method to control the bursting crack width in concentric anchorage zones. Four specimens with different bearing plate ratios have been designed and tested to validate the proposed method.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.279-282
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• 2008

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of the end rotation of the overhang due to the vertical load. When the up-lifting force exceeds the clamp force of the fastener clip, the rail pad is out of fastener, which makes decrease the serviceability of the railway, such as noise and vibration. Furthermore, it is possible to reduce the safety of the track as the longitudinal resistance. This study is focused on guideline suggestion to decrease up-lifting force in the fastener adjacent to the civil joint of slab track of bridge throughout the parametric analysis between the vertical spring stiffness of the fastener as the material approach, the space of fastener adjacent to bridge transition, the rigidity of the girder as the geometrical approach and up-lifting force under the train load.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.1-10
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• 2019

In the construction of flat plate slabs, which are widely used for tall buildings but have relatively low flexural stiffness, serviceability problems such as excessive deflections and cracks are of great concern. To prevent excessive deflections at service load levels, current design codes require the minimum slab thickness, but the requirement could be unconservative because it is independent on loading and elastic modulus of concrete, both of which have significant effects on slab deflections. In the present study, to investigate the effects of the construction load of shored slabs, reduced flexural stiffness and moment distribution of early-age slabs, and creep and shrinkage of concrete on immediate and time-dependent deflections, numerical analysis was performed using the previously developed numerical models. A parametric study was performed for various design and construction conditions of practical ranges, and a new minimum permissible thickness of flat plate slabs was proposed satisfying the serviceability requirement for deflection. The proposed minimum slab thickness was compared with current design code provisions and numerical analysis results, and it agreed well with the numerical analysis results.

• Wind and Structures
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• v.32 no.4
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• pp.283-292
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• 2021

Performance-based seismic design (PBSD) is currently used for retrofitting of older buildings and the design of new buildings. Whereas, application of performance-based design for wind load is still under development. The tendency has been in the codes to increase wind hazard based on recent recorded events. Since tall buildings are highly susceptible to wind load, necessity for developing a framework for performance-based wind design (PBWD) has intensified. Only a few guidelines such as ASCE (2019) provide information on using PBWD as an alternative for code prescriptive wind design. Though wind hazards, performance objectives, analysis techniques, and acceptance criteria are explained, no recommendations are provided for several aspects like how to select a proper level of wind hazard for each target performance criterion. This paper is an attempt to explain current design philosophy for wind and seismic loads and inherent connection between the components of PBSD for development of a framework for PBWD of tall buildings. Recognizing this connection, a framework for PBWD based on limits set for serviceability and strength is also proposed. Also, the potential for carrying out PBWD in line with ASCE 7-16 is investigated and proposed in this paper.

• Nuclear Engineering and Technology
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• v.29 no.6
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• pp.444-450
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• 1997

The current ASME code for reinforced concrete containment structures are not based on probability concepts. The stochastic nature of natural hazard or accidental loads and the variations of material properties require a probabilistic approach for a rational assessment of structural safety and performance. The paper develops design load factors for the serviceability limit state of reinforced concrete containment structures. The target limit state probability is determined and the load factors are calculated by the numerical analysis. Design load factors are proposed and carried out the reliability assessments.

• KIEAE Journal
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• v.8 no.6
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• pp.63-70
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• 2008

Slim floor construction is becoming used throughout many countries. It combines the advantages of flat slab construction with significant inherent resistance to fire. The slim floor system with web openings leads to the reduction of its self-weight. Although the system has enough strength and stiffness, it is necessary to evaluate and improve the effects of dynamic vibration to be able to annoy the residents. Thus, this study evaluates the serviceability of vibration effects based on the dynamic test of five slim composite beams. Based on the experimental results, the initial stiffness and natural frequency of all specimens exhibit the similar trend regardless of the opening and the shape of cross section. The decrease in natural frequency is deeply related to the reduction in the stiffness of specimens and thus, it can be concluded that the damage of slim composite floor can be detected by the measurement of natural frequency instead of the load-carrying capacity and the stiffness.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.151-158
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• 2006

Structural health monitoring is concerned with the safety and serviceability of the users of structures, especially for the case of building structures and infrastructures. When considering the safety of a structure, the maximum stress in a member due to live load, earthquake, wind, or other unexpected loadings must be checked not to exceed the stress specified in a code. It will not fail at yield, excessively large displacements will deteriorate the serviceability of a structure. To guarantee the safety and serviceability of structures, the maximum displacement in a structures must be monitored because actual displacement is a direct assessment index on its stiffness. However, no practical method has been reported to monitor the displacement, especially for the case of displacement of high-rise buildings because of not to easy accessive. In this paper, it is studied displacement measuring method of high-rise buildings using LiDAR The method is evaluated by analyzing accuracy of measured displacements for existing building.

• Computers and Concrete
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• v.17 no.1
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• pp.67-86
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• 2016

Strengthening as well as correcting unsightly deflections of reinforced concrete (RC) beam may be accomplished by retrofitting. An innovative way to do this retrofitting that is proposed in this study utilizes turnbuckle to apply external post-tensioning. This Turnbuckle External Post-Tensioning (T-EPT) was experimentally proven to improve the serviceability and load carrying capacity of reinforced concrete beams. The T-EPT system comprises a braced steel frame and a turnbuckle mechanism to provide the prestressing force. To further develop the T-EPT, this research aims to develop a numerical scheme to analyze the structural performance of reinforced concrete beams with this kind of retrofitting. The fiber method analysis was used as the numerical scheme. The fiber method is a simplified finite element method that is used in this study to predict the elastic and inelastic behavior of a reinforced concrete beam. With this, parametric study was conducted so that the effective setup of doing the T-EPT retrofitting may be determined. Different T-EPT configurations were investigated and their effectiveness evaluated. Overall, the T-EPT was effective in improving the serviceability condition and load carrying capacity of reinforced concrete beam.

• International Journal of High-Rise Buildings
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• v.3 no.3
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• pp.199-204
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• 2014

W-Project is 70-story mixed-use residential building complex project in Busan, the second biggest city in South Korea. As it is a high rise building complex located at the coast, the residents have great ocean view from the height. Though, there were many difficult challenges to be solved to secure structural safety and meet the serviceability requirements. As it is located on the reclaimed land, securing the foundation bearing capacity on soft soil is the first issue to be solved for the stable structure. W-Project. Busan on the way usual track of typhoon, wind load on structure is also critical for structural safety and serviceability for occupants due to wind vibration. This paper will address process of lateral load resisting structural system of W-Project.