EVALUATION METHOD FOR ALLOWABLE SHORT-TERM FLEXURAL STRENGTH AND YIELD STRENGTH OF CONCRETE-FILLED STEEL TUBULAR BEAM-COLUMNS

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Takashi Fujinaga ◽  
Tomoya Kawabata
Keyword(s):  
Flexural Strength ◽  
Yield Strength ◽  
Evaluation Method ◽  
Steel Tube ◽  
Superposition Method ◽  
Short Term ◽  
Restoring Force ◽  
Beam Columns ◽  
Slope Factor ◽  
The Moment

According to the Recommendations for Design and Construction of Concrete Filled Steel Tubular Structures from Architectural Institute of Japan, the allowable short-term flexural strength (ASFS) can be used as the yield strength for the restoring force characteristics model of concrete-filled steel tube (CFST) members. Therefore, it is necessary to examine whether the ASFS can be appropriate as an alternative for the yield strength. Furthermore, as the ASFS is typically calculated using the superposition method, the value of the deformation at the superposed strength cannot be evaluated. To address these issues, in this study, numerical analysis was conducted on the moment-curvature relation of CFST column sections using the finite fiber method. The characteristics of the point of ASFS and evaluation method for flexural yield strength in a broad sense were examined using the slope factor and strength satisfaction factor methods. The corresponding slope factor is larger than the value (1/3) that is generally used for the yield strength definition. Therefore, using the ASFS is as the yield strength of the CFST section is reasonable. Additionally, the formula for the curvature at the ASFS was also proposed.

EFFECT OF STRAIN-STRESS RELATIONSHIP OF STEEL TUBE ON THE INITIAL STIFFNESS OF SQUARE CFT COLUMNS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Ryo Handa ◽  
Masae Kido ◽  
Mao Liu ◽  
Keigo Tsuda
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Bending Moment ◽  
Steel Tube ◽  
Force Characteristic ◽  
Initial Stiffness ◽  
Short Term ◽  
Restoring Force ◽  
Strain Stress ◽  
Cft Column

The restoring force characteristic of a concrete filled steel tubular (CFT) column is modeled with three straight lines which show the relation of M-R. The initial stiffness is calculated by assuming that the steel and concrete portions are fully effective and materials are elastic. The first break point is the yield bending moment of the CFT column. The yield bending moment is defined by the bending moment when a part of the cross-section yield or the allowable strength for short-term loading obtained by the superposed strength method. It is supposed that the theoretical initial stiffness obtained by assuming that the whole cross section is effective is different from the real one. This study aims to clarify effects of strain-stress relation on the yield strength and allowable strength for short-term loading and the initial stiffness. Three types of stress-strain relations for steel are used, elastic-perfectly plastic model, Menegotto-Pinto's model and Morino's model. According to the analytical results, the difference between allowable strength and yield strength becomes larger as the axial load ratio, indexes Rh and k which are used in Menegotto-Pinto's model and Morino's model increase.

STRESS STATE OF STEEL TUBE OF SQUARE CFT COLUMNS WHICH REACHED SHORT-TERM ALLOWABLE STRENGTH

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mao Liu ◽  
Ryo Handa ◽  
Masae Kido ◽  
Keigo Tsuda
Keyword(s):  
Stress State ◽  
Yield Strength ◽  
Axial Force ◽  
Compressive Force ◽  
Steel Tube ◽  
Effective Length ◽  
Short Term ◽  
Damage State ◽  
Short Columns ◽  
Cft Column

The allowable strength was compared with the yield strength of CFT short columns subjected to constant axial force and horizontal force in previous studies. The yield strength of CFT columns is determined by 2/3 of compressive force of concrete in most cases. And the yield strength of CFT columns is smaller than the allowable strength. However, as an important index representing the damage state of CFT column, the stress state of steel tube when the CFT column reaches the short-term allowable strength is not clarified. The objective of this study is to make clear whether the steel tube yielded when the short-term allowable strength of square CFT column is reached by an analytical method. The analytical parameters are the effective length to depth ratio, axial force ratio and width to thickness ratio. The range of parameters in the cases which the steel tubes yield before the CFT columns reaches the allowable strength are shown and the decrease of stiffness in these cases are discussed.

scholarly journals Performance of Retrofitted Self-Compacting Concrete-Filled Steel Tube Beams Using External Steel Plates

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Ahmed A. M. AL-Shaar ◽  
Mehmet Tolga Göğüş
Keyword(s):  
Theoretical Model ◽  
Flexural Strength ◽  
Energy Absorption ◽  
Failure Modes ◽  
Steel Tube ◽  
Steel Plates ◽  
Self Compacting Concrete ◽  
Moment Capacity ◽  
Concrete Filled Steel Tube ◽  
The Moment

Self-compacting concrete-filled steel tube (SCCFST) beams, similar to other structural members, necessitate retrofitting for many causes. However, research on SCCFST beams externally retrofitted by bolted steel plates has seldom been explored in the literature. This paper aims at experimentally investigating the retrofitting performance of square self-compacting concrete-filled steel tube (SCCFST) beams using bolted steel plates with three different retrofitting schemes including varied configurations and two different steel plate lengths under flexure. A total of 18 specimens which consist of 12 retrofitted SCCFST beams, three unretrofitted (control) SCCFST beams, and three hollow steel tubes were used. The flexural behaviour of the retrofitted SCCFST beams was examined regarding flexural strength, failure modes, and moment versus deflection curves, energy absorption, and ductility. Experimental results revealed that the implemented retrofitting schemes efficiently improve the moment carrying capacity and stiffness of the retrofitted SCCFST beams compared to the control beams. The increment in flexural strength ranged from 1% to 46%. Furthermore, the adopted retrofitting schemes were able to restore the energy absorption and ductility of the damaged beams in the range of 35% to 75% of the original beam ductility. Furthermore, a theoretical model was suggested to predict the moment capacity of the retrofitted SCCFST beams. The theoretical model results were in good agreement with the test results.

FLEXURAL STRENGTH OF SQUARE CFT BEAMCOLUMNS WHEN DAMAGED WITH CONCRETE CRACKS

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Daijiro Fujioka ◽  
Masae Kido ◽  
Mao Liu ◽  
Hiroki Ikeda
Keyword(s):  
Yield Strength ◽  
Axial Force ◽  
Tensile Strain ◽  
Bending Moment ◽  
Steel Tube ◽  
Lateral Stiffness ◽  
Beam Columns ◽  
Concrete Crack ◽  
Force Ratio ◽  
The Relationship

The lateral stiffness of CFT beam-columns is considered to decrease because of the damage by the concrete crack or yielding of the materials however the relationship between two phenomena is not clear. It is necessary to clarify the strength when the CFT columns damaged by the concrete crack for evaluating the lateral stiffness of CFT beam-columns properly. The purposes of this study are to calculate the flexural crack strength of a square CFT section and to compare them with the yield strength. The analysis is carried out as follows; 1) assuming the stress-strain relationships of materials and the strain and stress distribution of the cross-section, 2) setting the limit of the tensile strain of concrete and 3) calculating the relation between the axial force and the bending moment when the strain of concrete reaches the limit tensile strain. Parameters are width-thickness ratio, the yield strength of a steel tube and compressive strength of concrete. As a result of the analysis, we showed that the axial force ratio is 0.2 ~0.3 when the flexural crack strength and the yield strength are the same. It is concluded that the lateral stiffness decreases because of the crack of concrete-and not from the yielding of materials--when the axial force ratio is smaller than 0.2~0.3.

Perencanaan Strategi TIK Proses Belajar Mengajar di Learning Center

2017 ◽  
Vol 8 (1) ◽  
pp. 22-28
Author(s):  
Sunardi Sunardi ◽  
Dina Fitria Murad
Keyword(s):  
Process Improvement ◽  
Business Strategy ◽  
Educational Institution ◽  
Learning Center ◽  
Language Training ◽  
Short Term ◽  
Participant Satisfaction ◽  
Strategy Planning ◽  
The Moment

BINUS Center is the informal educational institution that organizes IT and language training. Inrecent years the revenue BINUS Center continues to decrease, it is evident from the outlet  BINUS Center decreased from year to year. The purpose of making this research is to make strategy planning Business & ICT, create new models of learning supported by ICT strategy,test and measure the results obtained, and then made some strategic ideas at the moment and will come in the form of short-term priorities, medium and long term. The result is a cost that can be in the efficiency, a more flexible, first-class runs with a minimal number of participants, participant satisfaction, and competitive advantage.  Keywords: business strategy, ICT strategy, business process improvement, priority.

Shear response of steel fiber reinforced recycled concrete-filled steel tube columns

2021 ◽  
pp. 136943322110093
Author(s):  
Zhenzhen Liu ◽  
Yiyan Lu ◽  
Shan Li ◽  
Jiancong Liao
Keyword(s):  
Axial Compression ◽  
Steel Fiber ◽  
Steel Tube ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Superposition Method ◽  
Fiber Reinforced ◽  
Concrete Filled Steel Tube ◽  
Shear Span

A comprehensive study of the shear characteristics of steel fiber reinforced recycled concrete-filled steel tube (SRCFST) columns is conducted. 50 CFST stub columns are tested with the variables of steel tube diameter-thickness ratio ( D/t), shear span-to-depth ratio (λ), axial compression ratio ( n), and concrete mix. Two types of cements, three recycled aggregate percentages, three water-cement ratios, and three steel fiber contents are considered in design of concrete mixes. The experimental results show that SRCFST columns present the coincident shear behavior of the ordinary CFST columns. As λ is increased, shear resistance shows a downtrend, while the flexural strength presents an increasing trend. Imposing axial compression or thickening steel tube contributes to an adequate safety margin in plastic period. Based on the contributions superposition method, a predicted model of the shear capacity of SRCFST columns is proposed in consideration of shear-span ratio, axial compression, and self-stress.

scholarly journals Joint Discussion 4 UV astronomy: stars from birth to death

2006 ◽  
Vol 2 (14) ◽  
pp. 169-194
Author(s):  
Ana I. Gómez de Castro ◽  
Martin A. Barstow
Keyword(s):  
High Resolution ◽  
Uv Spectroscopy ◽  
Broad Band ◽  
Mission Planning ◽  
High Resolution Spectroscopy ◽  
Low Resolution ◽  
Short Term ◽  
Uv Astronomy ◽  
Optical Telescope ◽  
The Moment

AbstractThe scientific program is presented as well a the abstracts of the contributions. An extended account is published in “The Ultraviolet Universe: stars from birth to death” (Ed. Gómez de Castro) published by the Editorial Complutense de Madrid (UCM), that can be accessed by electronic format through the website of the Network for UV Astronomy (www.ucm.es/info/nuva).There are five telescopes currently in orbit that have a UV capability of some description. At the moment, only FUSE provides any medium- to high-resolution spectroscopic capability. GALEX, the XMM UV-Optical Telescope (UVOT) and the Swift. UVOT mainly delivers broad-band imaging, but with some low-resolution spectroscopy using grisms. The primary UV spectroscopic capability of HST was lost when the Space Telescope Imaging Spectrograph failed in 2004, but UV imaging is still available with the HST-WFPC2 and HST-ACS instruments.With the expected limited lifetime of sl FUSE, UV spectroscopy will be effectively unavailable in the short-term future. Even if a servicing mission of HST does go ahead, to install COS and repair STIS, the availability of high-resolution spectroscopy well into the next decade will not have been addressed. Therefore, it is important to develop new missions to complement and follow on from the legacy of FUSE and HST, as well as the smaller imaging/low resolution spectroscopy facilities. This contribution presents an outline of the UV projects, some of which are already approved for flight, while others are still at the proposal/study stage of their development.This contribution outlines the main results from Joint Discussion 04 held during the IAU General Assembly in Prague, August 2006, concerning the rationale behind the needs of the astronomical community, in particular the stellar astrophysics community, for new UV instrumentation. Recent results from UV observations were presented and future science goals were laid out. These goals will lay the framework for future mission planning.

Long-Term Deformations of Strengthened Reinforced Concrete Linear Elements

2016 ◽  
Vol 691 ◽  
pp. 51-60 ◽  
Author(s):  
Martin Krizma ◽  
Lubomir Bolha
Keyword(s):  
Reinforced Concrete ◽  
Long Term Results ◽  
Short Term ◽  
Limit States ◽  
Linear Elements ◽  
Repeated Load ◽  
The Moment ◽  
Concrete Elements ◽  
Fiber Fabric

The issue of strengthening the damaged linear reinforced concrete elements have been engaged since 2008. We focused on the analysis of resistance and the characteristics of limit states of serviceability in the damaged and subsequently strengthened elements at a short-term loading. In the introduction phase, the strengthening of the elements was carried out with the following procedures – installation of an overlayer on the coupling board or a combination of the board and use of glass – fiber fabric (GFRP). The strengthening was also affected by the type of contact (reinforced/non-reinforced) – the deformed element/coupling board and its effect on resistance, type of deformation and serviceability. In the non-reinforced contact, we applied some of the types of adjustments to the surface of the strengthened element. At the moment, we are dealing with the effects of time and repeated load on the strengthened elements. The results correspond to the reinforced contact. The values are compared with the short-term results of the strengthened beams and with the long-term results of the beams prepared for strengthening.

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