• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.97-105
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• 2010

The displacements of steel deck bridge due to construction step are measured, and three dimensional analysis with full modeling is carried out to compare with the measured results. Three dimensional structural analyses considering construction step by large block construction method are accomplished with verified model. The conclusions are as follows. 1. Comparing the data of grid analysis with the result of 3D full modeling in steel deck bridge, the design method using grid analysis has a limit for describing the displacements of curved bridge. The analysis of 3D full modeling has been proved as more accurate method. The differentiation of results in two methods is about 10%~20%. 2. It is verified that the maximum displacement of during construction is 1.7 times larger than the displacement of final construction. 3. The bridge behavior considering the construction step is somewhat different from that of final stage in whole structure and the displacement and stress during construction is larger than that of final construction. Therefore, it needs the reasonable structural design considering the construction step to get economical efficiency and a high competitive construction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.7-8
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• 2016

The use of half PC slab is increasing to shorten construction period. Because the drying shrinkage of topping concrete is restrained by PC slab, the tensile stress is generated at the topping concrete and the cracks can be occurred at the topping concrete due to drying shrinkage. Therefore, it is important to predict the tensile strain of half PC slab due to drying shrinkage to improve the quality of half PC slab. However, there is no studies on prediction of shrinkage behavior of half PC slab yet. Therefore, in this study, half PC slab was made, and the predictability of tensile strain generated at half PC slab due to drying shrinkage was investigated. The step by step method considering creep was used to estimate the tensile strain of half PC slab. In result, good agreement was obtained between the analytical and experimental values.

• Steel and Composite Structures
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• v.18 no.5
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• pp.1197-1214
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• 2015

There is a great difference in mechanical behavior between design model one-time loading and step-by-step construction process. This paper presents practical computational methods for simulating the structural behavior of long-span rigid steel structures during construction processes. It introduces the positioning principle of node rectification for installation which is especially suitable for rigid long-span steel structures. Novel improved nonlinear analytical methods, known as element birth and death of node rectification, are introduced based on several calculating methods, as well as a forward iteration of node rectification method. These methods proposed in this paper can solve the problem of element's 'floating' and can be easily incorporated in commercial finite element software. These proposed methods were eventually implemented in the computer simulation and analysis of the main stadium for the Universiade Sports Center during the construction process. The optimum construction scheme of the structure is determined by the improved algorithm and the computational results matched well with the measured values in the project, thus indicating that the novel nonlinear time-varying analysis approach is effective construction simulation of complex rigid long-span steel structures and provides useful reference for future design and construction.

• Structural Engineering and Mechanics
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• v.20 no.6
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• pp.673-693
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• 2005

A general step-by-step simulation for the time-dependent analysis of segmentally-erected prestressed concrete box-girder bridges is presented. A three dimensional finite-element model for the balanced-cantilever construction of segmental bridges, including effects of the load history, material nonlinearity, creep, shrinkage, and aging of concrete and the relaxation of prestressing steel was developed using ABAQUS software. The models included three-dimensional shell elements to model the box-girder walls and Rebar elements representing the prestressing tendons. The step-by-step procedure allows simulating the construction stages, effects of time-dependent deformations of materials and changes in the structural system of the bridges. The structural responses during construction and throughout the service life were traced. A comparison of the developed computer simulation with available experimental results was conducted and good agreement was found. Deflection of the bridge deck, changes in stresses and strains and the redistribution of internal forces were calculated for different examples of bridges, built by the balanced-cantilever method, over thirty-year duration. Significant time-dependent effects on the bridge deflections and redistribution of internal forces and stresses were observed. The ultimate load carrying capacities of the bridges and the behavior before collapse were also determined. It was observed that the ultimate load carrying capacity of such bridges decreases with time as a result of time-dependent effects.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.99-104
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• 2012

A turnelling work beneath roadways or railways in use is unsafe and dangerous. A turnelling method should be analytically and experimentally studied to verify stability and safety of excavating works by construction step. The conventionally analytical method was ineffective in computational time and cost, so the new analytical method named homogenuity method, was developed and verified compared with analytical results. That method was applied to parameterly study the effect of distance of steel supports and overburdening height of soil. It showed that the homogenuity method was very practical and effective in step-by-step analysis considering construction sequences. A measuring device was set at the construction field and mechanical behavior was monitored during construction. Measuring values are larger than analytical values because impact of inserting steel pipes, lowering level of underground water and vibration of passing vehicles affected soil density during construction, but those values were within allowable limits.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.27-35
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• 2010

The structures built under the groundwater level are affected by the buoyancy force, which is hydrostatic pressure in the up direction. Recently, buoyancy-resistant anchor method has been applied in many cases of the construction of the important structure of large size, which is built under the groundwater level so that it takes high uplift pressure. Even if the construction cost of the method is very high, it surely increases the safety rate. However, the diagnosis of the performance of the buoyancy-resistant permanent anchor and the investigation of resistance mechanism are still insufficient. Especially, the long-term behavior of the anchor has not been studied well due to the difficulty in observation procedure. The contribution of this paper is the establishment of reasonable design methodology. We have measured anchor axial forces for 10 years after the construction, by using an automated measurement and a manual measurement by establishing a load cell in anchor head. Through the data collected from the measurements, we analyze the construction-step behavior of the anchor according to the self-weight variation of the building and the long-term behavior (i.e. movement within 10 years after the construction) of the anchor according to the passage of time.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.265-268
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• 2008

In this paper behavior of U-Channel Bridge (UCB) and the slab design considering construction sequence was studied. The segments of UCB are produced in the factory and transported to the site by trailers, and the segments are fabricated in the construction field. In this sequence the supporting conditions are changed. Four steps that were the segment precasting step, the segment carrying step, the segment placed on the erection beam step, and the completion step were chosen by supporting condition. In each step model using the frame and plate elements was proposed and structural analysis was performed. Four construction steps were to be considered in the process of slab analysis. The design method of slab was proposed considering construction sequence.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.55-62
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• 2007

The structural safety of long span bridges such as suspension bridges is smaller under the construction stage than in the completion. But the importance of construction sequences has been neglected in most of safety check programs. On this study is developed the structural analysis method of suspension bridges considering construction sequences and structural analyses are performed by step by step during construction. This can be used to determine the safest erection method. The results shows that the more critical structural behavior appears under construction than after completion.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.143-151
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• 1999

An analytical study on the behavior of composite beams, which are composed of cold-formed profiled steel sheeting and normal strength concrete, is described. An analytical method to trace the nonlinear behavior of a composite beam is developed to include the nonlinear material properties of steel sheeting, reinforcing steel bar and concrete. A simple Power Model has also been proposed for the nonlinear moment-curvature relation of the composite beam. The model, which has been originally used to predict the flexural capacity of the beam to column connections, is adapted to the composite beams. The load-deflection behavior of the beams has been simulated by the step-by-step numerical integration using the moment-curvature relation obtained by the Power Model. The results have been compared with test results.

• Structural Engineering and Mechanics
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• v.63 no.1
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• pp.77-88
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• 2017

Correction Factor Method (CFM) is one of the earliest methods for simulating the actual behavior of structure according to construction sequences and practical implementation steps of the construction process which corrects the results of the conventional analysis just by the application of correction factors. The most important advantages of CFM are the simplicity and time-efficiency of the computations in estimating the final modified forces of the beams. However, considerable inaccuracy in evaluating the internal forces of the other structural members obtained by the moment equilibrium equation in the connection joints is the biggest disadvantage of the method. This paper proposes a novel method to eliminate the aforementioned defect of CFM by using the column shortening correction factors of the CFM to modify the axial stiffness of columns. In this method, the effects of construction sequences are considered by performing a single step analysis which is more time-efficient when compared to the staged analysis especially in tall buildings with higher number of elements. In order to validate the proposed method, three structures with different properties are chosen and their behaviors are investigated by application of all four methods of: conventional one-step analysis, sequential construction analysis (SCA), CFM, and currently proposed method.