• Journal of Korean Association for Spatial Structures
• /
• v.10 no.1
• /
• pp.75-84
• /
• 2010

According to the available study and experimental data about the long term behavior of CFT(Concrete Filled Tube) columns, the creep and of concrete in CFT columns are smaller than those of RC columns because of the confinement effect of outer steel columns. In this study, the uncertainties associated with assumed values for concrete properties such as strength, creep coefficients, and service load have been considered and analyzed for the prediction of time-dependent column shortening of CFT column. The CFT column shortening analysis using Monte Carlo method is proposed and an of a 37 story tall building with CFT columns is studied for illustration. According to the results obtained by the probability analysis with multi parameters, the effect of variation coefficient for 3 parameters is investigated considering confidence interval.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.397-402
• /
• 1998

The objectives of this paper are to estimate differential column Shortening and to determine appropreate compensation amount in 52 story Amatapura Apartment in Indonesia. for this, a computer program based on PCA and CEB-FIP code is developed. The results show that Elastic and Creep strain are the main factors of column shortening and the maximum differential shortening is appeared near the middle of the building height. The results between field survey and estimation have some difference, the most influential factor of the difference can be lateral restraints provided by horizontal members, which cannot be handled in this developed program. Hence introducing the modification factors from various field survey, this program can be used properly in design and construction procedures.

• Structural Engineering and Mechanics
• /
• v.51 no.6
• /
• pp.989-1003
• /
• 2014

In the preliminary design stage of an RC 3D-frame, repeated sequential analyses to determine optimal members' sizes and the investigation of the parameters required to minimize the differential column shortening are computational effort consuming, especially when considering various types of loads such as dead load, temperature action, time dependent effects, construction and live loads. Because the desired accuracy at this stage does not justify such luxury, two backpropagation feedforward artificial neural networks have been proposed in order to approximate this information. Instead of using a commercial software package, many references providing advanced principles have been considered to code a program and generate these neural networks. The first one predicts the typical amount of time between two phases, needed to achieve the minimum maximorum differential column shortening. The other network aims to prognosticate sequential analysis results from those of the simultaneous analysis. After the training stages, testing procedures have been carried out in order to ensure the generalization ability of these respective systems. Numerical cases are studied in order to find out how good these ANN match with the sequential finite element analysis. Comparison reveals an acceptable fit, enabling these systems to be safely used in the preliminary design stage.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2009.11a
• /
• pp.81-85
• /
• 2009

In the recent years, the high strength concrete has increasingly been used according to extending market of tall buildings. However, Ministry of Land, transport and Maritime Affairs was established by law with an alternative plan after June 2008 because of the weakness of high strength concrete accompanied spalling phenomena in fire. The mix design of concrete has to properly meet standards which are the spalling resistance of concrete and limited temperature of steel reinforcement. The fire proof concrete mixed fiber has widely been used to meet spalling safety on the many construction sites, the most researches about the fire proof concrete mixed fiber had being carried out focused on fire resistance, compressive strength and cast in place of concrete. But the most important thing is column shortening used the fire proof concrete within the vertical members. In this paper, the fire proof concrete filled spalling safety standards was experimented by required material when the column shortening is revised between normal concrete and fire proof concrete mixed fiber and then the results have done a comparative analysis. Also, The paper aimed to indicate a basic data for revision of column shortening of fire proof concrete.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.23 no.2
• /
• pp.139-152
• /
• 2010

This study presents graphic-user interface computer program for optimal compensation of differential column shortening with high field applicability. The implemented system can perform both relative and mixed compensation while satisfying both performance and construction constraints. In the proposed system the shape of the structure before and after compensation can be checked graphically, and the results of compensation of each stories can be printed in drawings which can be directly used as the report of column shortening. The field-applicability of the implemented system was verified by applying it to the four reinforced concrete residental buildings of 61, 42, 49 and 53 stories where compensation of differential column shortening had already been performed. Using the implemented system, compensation can be performed easily with the various constraint conditions and was able to acquire rational compensation results for the cases where conventional method was not successful.

• Journal of the Korea Concrete Institute
• /
• v.18 no.1 s.91
• /
• pp.101-108
• /
• 2006

Accurate prediction of time-dependent column shortening is essential for tall buildings in both strength and serviceability aspects. The uncertainty associated with assumed values for concrete properties such as strength, creep, and shrinkage coefficients should be considered for the prediction of time-dependent column shortening of tall concrete buildings. In this study, the column shortenings of 41-story tall concrete building are predicted using monte carlo simulation technique based on the probabilistic analysis. The probabilistic column shortenings considering confidence intervals are compared with the actual column shortenings by field measurement. The time-dependent strains measured at tall bearing wall building were generally lower than the predicted strains and the measured values fell within a range ${\mu}-1.64$, confidence level 90%.

• Advances in concrete construction
• /
• v.10 no.6
• /
• pp.527-536
• /
• 2020

In this study, a process is proposed to calculate analytical correction values for the vertical shortening of all columns on all floors in a high-rise building that minimizes the error between the structural analysis predictions and values measured during construction. The weight ratio and the most probable value were accordingly considered based on the properties of the shortening value analyzed at several points in each construction stage and the distance between these measured points and unmeasured points at which the shortening was predicted. The effective range and shortening value normalization were considered using the column grouping concept. These tools were applied to calculate the error ratio between the predicted and measured values on a floor where a measured point exists, and then determine the estimated error ratio and estimated error value for the unmeasured point using this error ratio. At points on a floor where no measured point exists, the estimated error ratio and the estimated error value were calculated by applying the most probable value considering the weight ratio for the nearest floor where measured points exist. In this manner, the error values and estimated error values can be determined at all points in a structure. Then, the analytical correction value, defined as this error or estimated error value, was applied by adding it to the predicted value. Finally, the adequacy of the proposed correction method was verified against measurements by applying the analytical corrections to all unmeasured points based on the points where the measurement exists.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.6
• /
• pp.391-399
• /
• 2019

In this study, an analytical method was proposed to correct the analysis results and minimize the errors between column shortening predictions and real values in high-rise buildings. In this regard, the construction sequence analysis of 41-story reinforced concrete buildings was performed and the results were compared to four assumed field measurements that were divided into the column and the core. The analysis correction was applied at a stage over the error limit in the column and at all stages in the core. Since the error occurred continuously after the analysis was corrected, additional corrections of the analysis resulted in a smaller error. By applying the proposed analytical correction method, it was confirmed that the long-term shortening value can be accurately predicted.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.23 no.4
• /
• pp.395-401
• /
• 2010

The vertical members of structures are shortened as time goes on. Because structures have been high-rising and atypical there should be different axial loads among vertical members and it causes differential column shortenings. The differential column shortening add stresses to connections, make slab tilt, and damage to non-structural components. To reduce these influences compensation is need. The rational compensation means the exact expectation of amounts of column shortenings and the reasonable corrections. The expectation of column shortenings are more exact as researched, however, there is little research about the compensation. This paper presents the average correction method and the constraints for differential column shortenings considering errors due to the construction precision. The relations between constraints and the number of correction groups give an objective criterion for decision of constraints.

• International Journal of High-Rise Buildings
• /
• v.6 no.1
• /
• pp.73-82
• /
• 2017

Vertical shortening in tall buildings would be of little concern if all vertical elements shortened evenly. However, vertical elements such as walls and columns may shorten different amounts due to different service axial stress levels. With height, the differential shortening may become significant and impact the strength design and serviceability of the building. Sometimes column transfers or other vertical structural irregularities may cause differential shortening. If differential shortening is not addressed properly, it can impact the serviceability of the building. This paper takes the perspective of a structural engineer in planning the design, predicting the shortening and its effects, and communicating the information to the contractor.