scholarly journals Bearing Capacity of Slender Concrete Columns

2018 ◽  
Vol 26 (4) ◽  
pp. 39-49
Author(s):  
Alfred Strauss ◽  
Thomas Zimmermann ◽  
Panagiotis Spyridis ◽  
Benjamin Täubling
Keyword(s):  
Cross Sections ◽  
Nonlinear Modeling ◽  
Structural Response ◽  
Concrete Columns ◽  
Structural Elements ◽  
Nonlinear Method ◽  
Probabilistic Evaluation ◽  
Calculation Results ◽  
Buckling Failure ◽  
The One

Abstract The European standard for the design of concrete structures using nonlinear methods contains a deficit in global reliability for cases when concrete columns fail due to a loss of stability before reaching the design resistance in the critical cross-sections. A buckling failure is a brittle failure which occurs without warning, and the probability of its formation is markedly influenced by the slenderness of the column. The calculation results presented herein are compared with the results from experimental data. The paper aims to compare the global reliability of slender concrete columns with a slenderness of 90 and higher. The columns are designed according to the methods stated in EN 1992-1-1, namely, a general nonlinear method and methods based on nominal stiffness and nominal curvature. The mentioned experiments also served, on the one hand, as a basis for the deterministic nonlinear modeling of the columns and, subsequently, for the probabilistic evaluation of the variability of the structural response. Finally, the results may be utilized as thresholds for the loading of the structural elements produced. The paper aims at presenting a probabilistic design that is less conservative than the classic partial safety factor-based design and alternative ECOV method.

scholarly journals Tingkat Efisiensi Perhitungan Kolom Beton (Perbandingan PBI 1971 Dengan SNI 1991)

2019 ◽  
Vol 7 (2) ◽  
pp. 79-103
Author(s):  
Sri Nuryati ◽  
Sigit Suwanto
Keyword(s):  
Structural Analysis ◽  
Concrete Columns ◽  
Concrete Column ◽  
Reinforcing Steel ◽  
Structural Elements ◽  
Steel Quality ◽  
Constant Area ◽  
Concrete Quality ◽  
Calculation Results ◽  
Manual Calculation

The collapse of a column causes the collapse of the entire building that need a large cost for repairing. Therefore, special attention is needed when planning the columns, i.e. by providing a backup strength on columns which greater than other beams and other horizontal structural elements since there is no initial warning in a press-type of collapse. This study aims to determine the efficiency of square concrete column dimensions in case of column calculations after the revision of PBI 1971 to SNI 1991 standard both by manual calculation and using the Turbo Pascal-based application. Calculation utilized the elastic method and ultimate method with the assumption that column conditions are similar as well as the column data is taken from the calculation of reinforced portal structures. Concrete columns are made rectangle with dimensions of size 35 x 35 cm and size 75 x 75 cm, concrete quality K 225, steel quality U24 (2400 kg / cm²), modulus of steel elasticity 2.1. 10⁶ kg / cm² and 5 cm thick of concrete blanket, with the assumption that structural analysis has been conducted for calculating the boundary and moment loads, assuming that the column conditions are similar. In case of the ability to retain the load and moment by the column, assuming the constant area of ​​reinforcement in various dimensions, the results of the elastic method (PBI 1071) were smaller than the ultimate method (SK SNI 1991). The calculation results showed that the ultimate method was more efficient than the elastic method in terms of the efficiency of reinforcing steel use.

Statistical Comparison of the Results of Applying Several Methods in Checking Concrete Columns’ Fire Resistance

2016 ◽  
Vol 711 ◽  
pp. 572-579
Author(s):  
Maria Alzira Barros Ramalho ◽  
Miguel Chichorro Gonçalves
Keyword(s):  
Cross Sections ◽  
Fire Resistance ◽  
Room Temperature ◽  
Concrete Columns ◽  
Alternative Methodology ◽  
The Stability ◽  
The One ◽  
Comparison Of The Results ◽  
In Fire ◽  
Rectangular Columns

The main objective of this study is to help the structural designers so they can, quickly and efficiently, study the concrete columns’ fire resistance. The most expeditious methods of fire resistance verification in terms of ease of application by structural designers, the methods given in EN 1992-1-2 [1] in the form of tables (Method A, Method B and Method C), were used in the fire resistance verification of 12243 rectangular columns inserted in the stability projects of 63 buildings, carefully selected in order to be representative of the ones licensed in Portugal [2]. Noting that these methods lead to excessively conservative results, the authors developed an alternative methodology, also with expedite application, but leading to substantially less conservative results (although designed on the safety side). This methodology consists on the consultation of adimensional interaction diagrams in fire situation, Nfi/Mfi, developed using the 500oC Isotherm Method. In the development of these diagrams unexpected results were obtained in some columns’ cross-sections, for which the resistance at room temperature was lower than the one corresponding to a fire situation at level R60. Some of the factors that can contribute to the occurrence of these results are pointed out.

scholarly journals Optimization of reinforcing steel with genetic algorithms for the design of concrete columns

2021 ◽  
Author(s):  
Luis Fernando Verduzco
Keyword(s):  
Construction Industry ◽  
Cross Sections ◽  
Optimization Algorithm ◽  
Structural Engineering ◽  
Heuristic Algorithms ◽  
Concrete Columns ◽  
Reinforcing Steel ◽  
Structural Elements ◽  
Optimization Program ◽  
Concrete Elements

Is presented hereby the creation of an optimization program for the design of reinforcing steel for any type of structural elements which may be considered as columns, pillar, pilots or dies, subjected to flexo-compression mechanic stresses for rectangular cross sections elements with the support of numeric methods and meta-heuristic algorithms for the optimization of constructions costs, particularly the Genetic algorithm, adapting such algorithms to the optimization problem so that it makes the resultant designs practical and convenient for its application in the construction industry, based on certain criteria from NTC-17 and questioning other. It will be shown how such optimization algorithm was adapted to the problem, as well as other general numeric methods for engineering and others developed specifically for structural engineering for the optimal design of this sort of concrete elements. Moreover, sensibility cost analysis of unitary construction prices are presented as well, with which the objective function for the optimization algorithm was created. At the end, results of various experiments with and without the optimization program are shown, making comparisons between different structural models regarding cost and geometry.

Experimental Verification of Slender Reinforced Concrete Columns Design

2021 ◽  
Vol 322 ◽  
pp. 142-150
Author(s):  
Jakub Dobrý ◽  
Vladimír Benko ◽  
Miroslav Kováčik ◽  
Hannes Wolfger
Keyword(s):  
Reinforced Concrete ◽  
Experimental Verification ◽  
Building Materials ◽  
Experimental Tests ◽  
Concrete Columns ◽  
Order Theory ◽  
Loss Of Stability ◽  
Structural Elements ◽  
Nonlinear Method ◽  
Reinforced Concrete Columns

The columns have been part of the constructions since the beginning of the buildings and have retained their design and construction importance to the present. The advantage of using more slender elements are less material consumption and more usable space in the interiors. The continuous improvement of the building materials and the use of hybrid structural elements leads to the downsizing of the structural elements. The aim of this article is the nonlinear analysis of the slender rein-forced concrete columns and the loss of stability verified by the experimental tests. Nonlinear calculations can be considered as the most accurate calculation option for the load bearing structural elements. On the other hand, the effect of the “black box” has been, and will be the cause of a large number of building defects. In the Eurocode 2 in chapter 5.8.6 of the European Concrete Design Standard, there is a possibility of using the general nonlinear method in practice, even for the com-pressed elements. In the design of the slender structures, the influence of second-order theory is a very important part of the design. In this publication are described theoretical and experimental analyses of the slender columns, that failed due to loss of stability inside of their design interaction diagram - much sooner than the critical cross-sections reached its resistance. As a part of the experimental preparations, reinforced concrete columns were designed, based on numerous numerical analyses. Later, the chosen columns were tested in the laboratories of TU Wien in Vienna. Experimental verification is one of the main parts of my dissertation thesis.

scholarly journals Failure of Slender Concrete Columns Due to a Loss of Stability

2019 ◽  
Vol 27 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Vladimír Benko ◽  
Jakub Dobrý ◽  
Marek Čuhák
Keyword(s):  
Cross Sections ◽  
Linear Method ◽  
Bending Moment ◽  
Concrete Columns ◽  
Order Theory ◽  
Loss Of Stability ◽  
Non Linear ◽  
Calculation Results ◽  
European Code ◽  
The Impact

Abstract The European standard for the design of concrete structures that are likely to lose stability requires taking into account the effects of second order theory. This effect increases the impact of a bending moment due to member deformation and additional eccentricity. Slender members can be calculated by the use of a non-linear method. This approach shows a deficit in global reliability for cases where the concrete columns fail due to the loss of stability before reaching the design resistance in the critical cross-sections. Buckling is a brittle failure which occurs without any warning, and the probability of its formation is markedly influenced by the slenderness of the column. Here, the calculation results are presented and compared with the results from an experiment which was carried out in cooperation with STRABAG Bratislava LTD at the Central Laboratory of the Faculty of Civil Engineering SUT in Bratislava. The columns were designed according to the methods stated in STN EN 1992-1-1, namely, a general non-linear method. The focus of this study is to compare multiple approaches based on codes used in Germany (DIN 1045-1, 2001) and Austria (ÖNORM B 4700, 2001) with the present European code mentioned above. The paper aims to compare the global reliability of slender concrete columns with variable slendernesses of 90 and 160.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

scholarly journals Method for assessment of matching of total ankle joint endoprostheses based on CT data

2020 ◽  
Vol 6 (3) ◽  
pp. 396-397
Author(s):  
Heiner Martin ◽  
Josephine Wittmüß ◽  
Thomas Mittlmeier ◽  
Niels Grabow
Keyword(s):  
Cross Sections ◽  
Spline Functions ◽  
Moments Of Inertia ◽  
Cad System ◽  
Principal Moments Of Inertia ◽  
Principal Axes ◽  
Ct Data ◽  
The One ◽  
Relative Differences ◽  
Systemic Design

AbstractThe investigation of matching of endoprosthesis tibial components to the bone cross section is of interest for the manufacturer as well as for the surgeon. On the one hand, a systemic design of the prosthesis and the assortment is possible, on the other hand, a better matching implantation is enabled on the basis of experience of this study. CT sections were segmented manually using a CAD system and fitted by spline functions, then superseded with cross sections of the tibial component of a modified Hintermann H3 prosthesis. The principal moments of inertia, the direction of the principal axes and the area of the section were evaluated. Based on the relative differences of the principal moments of inertia, recommendations for application of the different prosthesis size and its selection with the surgery can be made.

Thermal and structural response of aerospike mounted on blunt-nose body

2020 ◽  
pp. 095441002097648
Author(s):  
Zhang ZhunHyok ◽  
Won CholJin ◽  
Ri CholUk ◽  
Kim CholJin ◽  
Kim RyongSop
Keyword(s):  
Aerodynamic Force ◽  
Coupling Effect ◽  
Angle Of Attack ◽  
Structural Response ◽  
Response Characteristic ◽  
Wave Drag ◽  
Hypersonic Vehicle ◽  
Loosely Coupled ◽  
Calculation Results ◽  
Blunt Nose

The inclusion of aerospike on blunt nose body of hypersonic vehicle has been considered to be the simplest and most efficient technique for a concurrent reduction of both aeroheating and wave drag due to hypersonic speed. However, the thermal and mechanical behavior of aerospike structure under the coupling effect of aerodynamic force and aeroheating remains unclear. In this study, the thermal and structural response of aerospike mounted on the blunt nose body of hypersonic vehicle was numerically simulated by applying 3 D fluid-thermal-structural coupling method based on loosely-coupled strategy. In the simulation, the angle-of-attack and the spike’s length and diameter are differently set as α = 0°–10°, L/D = 1–2 and d/D = 0.05–0.15, respectively. Through the parametric study, the following results were obtained. Firstly, the increase of vehicle’s angle-of-attack and spike’s length unfavorably affect the thermal and structural response of aerospike. Secondly, the increase of spike’s diameter can improve its structural response characteristic. Finally, the aerospike with the angle-of-attack of 0° and the length and diameter of L/D = 1 and d/D = 0.15, respectively, is preferred in consideration of the effect of flight angle-of-attack and spike’s geometrical structure on the thermal and structural response of spike and the drag reduction of vehicle. The numerical calculation results provide a technical support for the safe design of aerospike.

An unified approach to inelastic light scattering in Keldysh–Schwinger functional integral formalism

2015 ◽  
Vol 29 (07) ◽  
pp. 1550040 ◽  
Author(s):  
Hyun Cheol Lee
Keyword(s):  
Light Scattering ◽  
Cross Sections ◽  
Golden Rule ◽  
Functional Integral ◽  
Integral Formalism ◽  
Inelastic Light Scattering ◽  
Scattering Geometry ◽  
The One ◽  
Resonant Part ◽  
Functional Integral Formalism

We propose a theoretical framework which can treat the nonresonant and the resonant inelastic light scattering on an equal footing in the form of correlation function, employing Keldysh–Schwinger functional integral formalism. The interference between the nonresonant and the resonant process can be also incorporated in this framework. This approach is applied to the magnetic Raman scattering of two-dimensional antiferromagnetic insulators. The entire set of the scattering cross-sections are obtained at finite temperature, the result for the resonant part agrees with the one obtained by the conventional Fermi golden rule at zero temperature. The interference contribution is shown to be very sensitive to the scattering geometry and the band structure.

Theoretical studies on the one- and two-photon absorption of tetrabenzoporphyrins and phthalocyanines

2004 ◽  
Vol 82 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Xin Zhou ◽  
Ai-Min Ren ◽  
Ji-Kang Feng ◽  
Xiao-Juan Liu
Keyword(s):  
Dipole Moment ◽  
Cross Sections ◽  
Density Functional ◽  
Transition Dipole Moment ◽  
Photon Absorption ◽  
Transition Dipole ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Order Of Magnitude ◽  
The One

The one-photon absorption (OPA) properties of tetrabenzoporphyrins (TBPs) and phthalocyanines (Pcs) were studied using the semiempirical ZINDO method and time-dependent density functional theory (TDDFT), respectively. The compared results confirmed that the semiempirical ZINDO method was reasonably reliable when calculating the OPA of tetrabenzoporphyrins and phthalocyanines. On the basis of the OPA properties obtained from the ZINDO method, two-photon absorption (TPA) properties of two series of molecules were investigated, using ZINDO and sum-over-states (SOS) methods. The results showed that the TPA cross-sections of all molecules were in the range of 220.6 × 10–50 – 345.9 × 10–50 cm4·s·photon–1, which were in the same order of magnitude as the values reported in the literature. The relatively larger δ(ω) value for Pcs with respect to that for corresponding TBPs originates from larger intramolecular charge transfer, which can be characterized by the difference of dipole moment between S0 and S1 and the transition dipole moment between S1 and S5.Key words: two-photon absorption, ZINDO, sum-over-states, tetrabenzoporphyrin, phthalocyanines.

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