scholarly journals Size optimization of single edge folds for cold-formed structural members

2020 ◽  
pp. 73-86
Author(s):  
Serhii Bilyk ◽  
Vitalina Yurchenko
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Optimization Problem ◽  
Parametric Optimization ◽  
Optimization Problems ◽  
Structural Members ◽  
Single Edge ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Parametric Optimization Problem

Parametric optimization problem for single edge fold size in cold-formed structural members subjected to central compression has been considered by the paper. Determination the load-bearing capacity of the cold-formed structural members has been performed using the geometrical properties calculated based on the constructed “effective” (reduced) cross-sections taking into account local buckling effects in the section as well as distortional buckling effects. Single edge fold size in cold-formed C-profile has been considered as design variable. Linear convolution of criteria, namely minimization criterion of design area of stiffener cross-section and maximization criterion effective area of stiffener cross-section which defines it reduced load-bearing capacity due to flexural buckling has been used as optimization criterion. The parametric optimization problem has been solved using the method of objective function gradient projection onto the active constraints surface with simultaneous correction of the constraints violations. In order to realize the formulated optimization problem, software OptCAD intended to solve parametric optimization problems for steel structural systems has been used. Optimization results of the single edge folds for the cold-formed С-profiles manufactured by «Blachy Pruszyński» company, «BF FACTORY» company as well as «STEELCO» company have been presented by the paper. The results of the performed investigation can be used as recommendations for companies-manufacturers of the cold-formed profiles, as well as a guide for creation the national assortment base of the effective cold-formed profiles promoting wider implementation of cold-formed steel structures in building practice.

scholarly journals Load-bearing capacity of the steel-to-timber connections in fire temperature

2019 ◽  
Vol 262 ◽  
pp. 09005 ◽  
Author(s):  
Tomasz Domański ◽  
Kamil Kmiecik
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Bearing Capacity ◽  
Cross Section ◽  
Structural Members ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Steel Connections ◽  
In Fire ◽  
Fire Conditions

Connections are usually the weakest parts in most structures, especially in fire conditions. The load-bearing capacity of timber structures is often limited by the resistance of steel connection between timber structural members. The temperature distribution in the cross-section as well as the influence of steel fasteners on the charring of the timber members is necessary to predict the fire resistance of the connection. This paper presents a summary of results from numerical studies on the fire behaviour of the steel connections between timber structural members. To make the three-dimensional thermal models of the joints, the FE (finite element) programme SAFIR was used. Then, the finite element models of the connections were used to analyse the temperature distribution inside cross-sections under standard ISO-fire exposure. The failure modes from the literature were used to predict the load-bearing capacity of the steel connections at elevated temperatures. The reduction of the cross-section caused by charring, the reduction of embedment strength and the reduction of steel strength at fire conditions were taken into account in the calculations.

Study on the Data-Bases for Fire Engineering Design of Structural Steels Members

2012 ◽  
Vol 628 ◽  
pp. 156-160
Author(s):  
In Kyu Kwon ◽  
Hyung Jun Kim ◽  
Heung Youl Kim ◽  
Bum Yean Cho ◽  
Kyung Suk Cho
Keyword(s):  
Bearing Capacity ◽  
Fire Resistance ◽  
Engineering Method ◽  
Fire Tests ◽  
Structural Members ◽  
Data Bases ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
In Fire ◽  
Resistance Performance

Structural steel has been used since the early 1970’s in Korea as primary structural members such as columns, beams, and trusses. The materials have much higher strength such as fast construction, high load bearing capacity, high construction quality but those have a fatal weakness as well. Load-bearing capacity is going down when the structural members are contained in fire condition. Therefore, to protect the structural members made of steels from the heat energy the fire resistance performance required. Generally, the fire resistance performance have evaluated from the exact fire tests in fire furnaces. But the evaluation method takes much more time and higher expenses so, the engineering method requires. The engineering method not only adopts a science but also an engineering experience. In this paper, to make various data-bases for evaluation of structural members such as columns(H-section, RHS), beams, loaded fire tests were conducted and derived not only each limiting temperature but also fire resistance respectively.

LOAD-BEARING CAPACITY OF CONCRETE-FILLED STEEL COLUMNS

2009 ◽  
Vol 15 (1) ◽  
pp. 21-33 ◽  
Author(s):  
Artiomas Kuranovas ◽  
Douglas Goode ◽  
Audronis Kazimieras Kvedaras ◽  
Shantong Zhong
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Cross Section ◽  
Steel Tube ◽  
Sustained Load ◽  
Load Bearing Capacity ◽  
Concrete Core ◽  
Load Bearing

This paper represents the analysis of 1303 specimens of CFST experimental data. Test results are compared with EC4 provided method for determining the load‐bearing capacity of these composite elements. Several types of CFSTs were tested: both circular and rectangular cross‐sections with solid and hollow concrete core with axial load applied without and with moment, with sustained load and preloading. For circular cross‐section columns there is a good agreement between the test failure load and the EC4 calculation for both short and long columns with and without moment. For rectangular cross‐section columns the agreement is good except when the concrete cylinder strength was greater than 75 MPa, when many tests failed below the strength predicted by EC4. Preloading the steel tube before filling with concrete seems to have no effect on the strength. This paper also presents the stress distribution, confinement distribution and complete average longitudinal stress‐strain curves for concrete‐filled steel tubular elements. Based on the definition of the “Unified Theory”, the CFST is looked upon as an entity of a new composite material. In this paper, the research achievement of the strength and stability for centrifugal‐hollow and solid concrete filled steel tube are introduced. These behaviours relate to the hollowness ratio and the confining indexes of corresponding solid CFST. If the hollow ratio equals to 0,4–0,5 and over, the N‐ϵ relationship exists in steady descending stage. The critical stress of CFST elements stability is determined as an eccentric member with the initial eccentricity by use of finite element method. Santrauka Straipsnyje analizuojami 1303 betonšerdžių plieninių strypų bandinių eksperimentiniai duomenys. Duomenys lyginami su eurokode 4 pateiktais kompozitinių elementų laikomosios galios nustatymo metodais. Analizuojami šie betonšerdžių plieninių strypų bandinių tipai: pilnaviduriai ir tuščiaviduriai, apskrito ir stačiakampio skerspjūvio kolonos, kurių galuose veikia arba neveikia momentas, su iš anksto pridėta arba ilgalaike apkrova. Apskrito skerspjūvio kolonų laikomosios galios bandymų rezultatai atitinka skaičiavimų reikšmes, apskaičiuotas pagal eurokode 4 pateiktu metodu. Stačiakampio skerspjūvio elementų laikomosios galios reikšmių bandymo rezultatai puikiai atitinka teorines reikšmes, kai betono ritininis stipris nesiekia 75 MPa. Išankstinis elementų apkrovimas poveikio elementų laikomajai galiai beveik neturi. Taip pat nagrinėjami betonšerdžių elementų įtempių būvių pasiskirstymas, betono apspaudimo poveikis ir išilginių deformacijų ir įtempių kreivės. Pateikiama S. T. Zhong „Unifikuota teorija“, kuri nagrinėja kompozitinį elementą kaip visumą. Straipsnyje nagrinėjamos kompozitinio plieninio ir betoninio elemento stiprumo ir pastovumo sąlygos. Tokių elementų reikšmėmis. Jeigu tuštumos santykis lygus 0,4–0,5 ir daugiau, N-ε sąryšis yra kritimo stadijoje. Elgsenos stadijos keičiasi pagal tuštumos koeficientą.

Parametric Optimization for Structural Design Problems

2019 ◽  
Author(s):  
Krupakaran Ravichandran ◽  
Nafiseh Masoudi ◽  
Georges M. Fadel ◽  
Margaret M. Wiecek
Keyword(s):  
Structural Design ◽  
Optimization Problem ◽  
Parametric Optimization ◽  
Optimization Problems ◽  
Nonlinear Constraint ◽  
Computational Performance ◽  
Design Variables ◽  
Input Parameters ◽  
Parametric Optimization Problem ◽  
Objective Function Values

Abstract Parametric Optimization is used to solve problems that have certain design variables as implicit functions of some independent input parameters. The optimal solutions and optimal objective function values are provided as functions of the input parameters for the entire parameter space of interest. Since exact solutions are available merely for parametric optimization problems that are linear or convex-quadratic, general non-convex non-linear problems require approximations. In the present work, we apply three parametric optimization algorithms to solve a case study of a benchmark structural design problem. The algorithms first approximate the nonlinear constraint(s) and then solve the optimization problem. The accuracy of their results and their computational performance are then compared to identify a suitable algorithm for structural design applications. Using the identified method, sizing optimization of a truss structure for varying load conditions such as a varying load direction is considered and solved as a parametric optimization problem to evaluate the performance of the identified algorithm. The results are also compared with non-parametric optimization to assess the accuracy of the solution and computational performance of the two methods.

Estimation of Load-Bearing Capacity and Stiffness of Timber Beams with Through-Thickness Cracks

2013 ◽  
Vol 778 ◽  
pp. 361-368
Author(s):  
Anatoly Yakovlevich Naychuk
Keyword(s):  
Crack Length ◽  
Bearing Capacity ◽  
Cross Section ◽  
Span Length ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Crack Location ◽  
Crack Tips ◽  
Beam Height ◽  
Timber Beams

The results of experimental and theoretical study of the load-bearing capacity and stiffness of wooden beams with through-thickness cracks depending on their length and location throughout the height of cross-section are given. The analysis of the regularity of change of stress-strain state, stress intensity factors (SIF) and at crack tips, deflections and timber beams load-bearing capacity depending on beam span length versus cross-section height, crack length versus span length, crack location throughout beam height was made. It has been established that load-bearing capacity and stiffness of timber beams with through-thickness cracks depends not only on the crack length, but its location throughout cross-section height as well. Procedure of assessing load-bearing capacity and stiffness of timber beams with through-thickness cracks based on fracture mechanics methods is given.

scholarly journals The Torsion Problem of a Cylindrical Solid Taking Into Account the Material Weakening

2019 ◽  
pp. 29-36
Author(s):  
V E Wildemann ◽  
A I Mugatarov
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Structural Damage ◽  
Deformation Diagram ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Relative Angle ◽  
Supercritical Deformation ◽  
Cylindrical Solid ◽  
Angle Of Rotation

The weakening of the material begins reaching a critical level of stress state, is characterized by a decrease in the level of stress during growing deformations and can develop with an equilibrium accumulation of structural damage. The equilibrium accumulation of damage is possible if the given displacements of the boundary points are provided (that is, with “hard” loading) and if the rigidity of the loading system is sufficient. The design becomes unable to withstand the load only when zones with weakened connections are developed enough. Therefore, taking into account the full deformation diagram in the calculations allows to more accurately determine the load bearing capacity of the design. This paper gives an analytical solution for the problem of a homogeneous cylindrical solid torsion with a circular cross section with its hard loading taking into account the material weakening. Piecewise linear approximations of elastic and elastoplastic medium with a linear weakening at the supercritical deformation stage are considered. The diagrams are plotted regarding stress distribution over the cross section are given; the graphs of the maximum torque value and the extreme value of the relative angle of rotation on the parameters of the deformation diagram. The dependences of the torque on the relative angle of rotation of the sections for the stage of initial supercritical deformation, as well as the stage of supercritical deformation and fracture are determined. The graphs of the dependence of torque on the angle of rotation of the section are given. Reserves of the load bearing capacity of the design are identified. It is noted that taking into account the weakening of the material is expedient in strength calculations and in determination of the system’s safety factor.

scholarly journals Determination of the load-bearing capacity of «steel-wood» connections of LVL structures under tension

2021 ◽  
Vol 18 (1) ◽  
pp. 60-69
Author(s):  
Quoc Phong Tran ◽  
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Steel Plate ◽  
Experimental Studies ◽  
Steel Plates ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Dowel Connections ◽  
Wooden Structures

The article presents the results of calculation of the load-bearing capacity of connections of LVL structures under tension using cylindrical dowels in trusses and frames. The description of calculation schemes for determining the load-bearing capacity of connections with different location and sizes of steel plates in the connection is given. The influence of steel plate placement on the distribution of forces in the cross-section of samples is investigated. Based on the results of analytical and experimental studies, the load-bearing capacity of dowels during bending is considered, as well as the mechanism of wooden structures` fracture during chipping. A comparative analysis of the effectiveness of different schemes of dowel connections with three steel plates under tension is carried out.

scholarly journals The Efficiency of Utilisation of High-strength Steel in Tubular Profiles

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1193 ◽  
Author(s):  
Ieva Misiūnaitė ◽  
Viktor Gribniak ◽  
Arvydas Rimkus ◽  
Ronaldas Jakubovskis
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
High Strength Steel ◽  
Current Trend ◽  
Weight Ratio ◽  
High Strength ◽  
Beam Specimen ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Structural Applications

The use of high-strength steel (HSS) is a current trend of the construction industry. Tubular profiles are widely used in various structural applications because of their high stiffness-to-weight ratio, exceptional resistance to torsion, and aesthetic appearance. However, the increase of the strength for the same elastic modulus of the material and geometry of tubular profiles is often not proportional to the rise of the load-bearing capacity of the structural element. The obtained experimental results support the above inference. The study was based on the flexural test results of two groups of HSS and normal-strength steel (NSS) tubular specimens with a 100 × 100 × 4 mm (height × width × thickness) cross-section. Numerical (finite element) simulation results demonstrated that the shape of the cross-section influenced the efficiency of utilisation of HSS. The relationship between the relative increase of the load-bearing capacity of the beam specimen and the corresponding change of the steel strength determined the utilisation efficiency.

Experiments on Wall Panels with One-Sided Board Sheathing for Timber Structures

2017 ◽  
Vol 1144 ◽  
pp. 3-8
Author(s):  
Jiří Celler ◽  
Jakub Dolejs ◽  
Vera Hlavata
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Timber Structures ◽  
Bearing Material ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Glued Laminated Timber ◽  
Wall Panels ◽  
The Stability ◽  
Shaped Cross Section

Timber elements with an I-shaped cross-section are used as supporting elements in wall, ceiling and roof panels of light timber frames. The reinforcement of the panel (I-stud) is provided by means of glued timber composite I-shaped element consisting of a web made of a wood-based desk embedded into flanges of solid or glued laminated timber. The stability of the wall panels is usually ensured by sided board sheathing, which prevents buckling of studs in the plane of the wall or their twist. Walls with one-side board sheathing are used for some types of modern timber structures and their load bearing capacity is determined for situation when one-side sheathing burns down during fire or sheathing is not made of a load-bearing material.

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