Batten Plates Research Articles

Finite element model based test and analysis on ACHC short columns and hoop coefficient

In order to promote the application of angle-steel confined high-strength concrete (ACHC) columns in new construction and reinforcement projects of civil engineering, this paper designs 15 groups of ACHC short columns with a shear span ratio of 1.5 under axial compression by taking the hoop coefficient, strength grade of concrete and yield strength of steel as parameters. Based on the constitutive model of steel and confined concrete and considering hoop effect, the simulation analysis on them was carried out by ANSYS software, and the rationality of finite element modelling is verified by comparing it with the experimental data. The author investigated the influence of different hoop coefficients, different concrete strength grades and different yield strength of steel to the mechanic behaviour of ACHC short columns, and the results show that the influence of hoop coefficient to the bearing capacity and ductility is more significantly than other parameters. Considering the hoop effect of batten plate to concrete, the linear relationship between the influence factor of batten plates and the hoop coefficient is inverted by using 1stopt software. At last, the calculation formula of ultimate bearing capacity of ACHC short columns is gotten, and the design method and suggestion of short columns are put forward.

Ductility assessment of two-chord composite steel-concrete battened columns

The ductility of a column is one of the most important characteristics of a structure subjected to unexpected overloads, load reversals, blast loads or dynamic impacts. Structural ductile members are capable of dissipating large amounts of energy by undergoing large deformations before failure, hence providing early warning to the occupants of the building. Previous analyses conducted by the authors suggest that, in addition to the type of column (steel, reinforced concrete and composite steel–concrete), the applied measure of ductility as well as other factors (the materials used and the loading and boundary conditions) have a significant influence on a column’s ductility. This paper proposes a new approach to the analysis of the ductility of columns. This approach distinguishes between the column’s pre-peak, post-peak and total ductility, and develops ductility parameters based on the displacement and energy for each of these ductility types. Based on experimental and numerical research on two-chord composite steel–concrete columns subjected to vertical monotonic loads, the influence of concrete strength and batten plate spacing on the columns’ vertical ductility is evaluated. It is concluded that designing two-chord composite steel–concrete columns to have small batten plate spacing and a relatively low concrete strength class can maximise the vertical ductility.

Seismic behavior of composite walls with encased steel truss

This paper studies the seismic behavior of reinforced concrete (RC) walls with encased cold-formed and thin-walled (CFTW) steel truss, which can be used as an alternative to the conventional RC walls or steel reinforced concrete (SRC) composite walls for high-rise buildings in high seismic regions. Seven one-fourth scaled RC wall specimens with encased CFTW steel truss were designed, manufactured and tested to failure under reversed cyclic lateral load and constant axial load. The test parameters were the axial load ratio, configuration and volumetric steel ratio of encased web brace. The behaviors of the test specimens, including damage formation, failure mode, hysteretic curves, stiffness degradation, ductility and energy dissipation, were examined. Test results indicate that the encased web braces can effectively improve the ductility and energy dissipation capacity of RC walls. The steel angles are more suitable to be used as the web brace than the latticed batten plates in enhancing the ductility and energy dissipation. Higher axial load ratio is beneficial to lateral load capacity, but can result in reduced ductility and energy dissipation capacity. A volumetric ratio about 0.25% of encased web brace is believed cost-effective in ensuring satisfactory seismic performance of RC walls. The axial load ratio should not exceed the maximum level, about 0.20 for the nominal value or about 0.50 for the design value. Numerical analyses were performed to predict the backbone curves of the specimens and calculation formula from the Chinese Code for Design of Composite Structures was used to predict the maximum lateral load capacity. The comparison shows good agreement between the test and predicted results.

Experimental and numerical investigation of cold-formed steel double angle members under compression

This paper presents a numerical and experimental study of double angle members connected by batten plates under concentric and eccentric axial compression. The number of batten plates is varied to study the influence on the nominal axial strength. Numerical analyses are able to accurately predict the behavior and strength found in the experiments, except for long columns under eccentric axial compression where the composite section failed in major-axis flexural buckling. Two design hypotheses are compared to the results obtained: (i) non-composite action (no interaction between angles), with only local, flexural, and flexural-torsional buckling considered; and (ii) composite action (full interaction between angles), and the only considering local and minor-axis flexural buckling of the pair of angles. The two design hypotheses ignore load eccentricity. Numerical and experimental results for angles connected by bolted batten plates fall in between the design curves defined by methods (i) and (ii), while angles connected by welded batten plates have greater strength than the design curve defined by method (ii). The use of batten plates significantly increases the strength of the system, especially for members under eccentric compression. However, the strength remains constant after a certain number of batten plates are connected, and after a minimum batten plate width is reached.

Vertical Subway, Namely, an Internal Transport System in 1200 m Tall Building

This article deals with the topic of designing an efficient internal transport system in a 1200 m tall multifunctional building called the “World's Tower” due to its symbolism and specific architectural form. The building comprises four towers whose bases are 75 m/75 m long each and whose height is 1200 m. Two of the towers are located along the north-south axis while the two others along the east-west one. The towers are joined at the top which makes the building higher than ever before (even up to 2km). It has been achieved with the help of a batten plate joining the towers at the height of 900 m. The opposite towers are joined with the arch structure thanks to which the building constitutes the monument – the symbol of the unity of south and north, east and west. Additionally, the fifth component – a spherical structure with a diameter of 220 m has been placed on the batten plate. There are outlines of the continents on the elevation of the spherical structure. Thus, the whole building symbolizes the mankind that has taken the planet Earth under its wings. The internal transport system in the building has been called by the author a “vertical subway” due to its similarity to the actual subway system. The system consists of 40 elevator cars connected with each other and which, in a given shaft, move only in one direction, for example, they all move up and then they move one by one into the other shaft in which they go down. It creates so far unknown possibilities of using the internal transport systems in very tall buildings, as the “vertical subway” of this type can take a few thousand people at the same time and it can operate every three minutes at peak times. Two sets of these “trains” plus eight traditional elevators can work in the tallest buildings in the world while taking up only a small fraction of their area. It is a new quality in the vertical internal transport because of its efficiency which is several times bigger than the one of the vertical transport systems used so far.

WORLD’S TOWER - NAMELY, HOW TO BUILD A 1200 METRE TALL HOUSE

The purpose of the paper is to discuss the idea of the construction of the World’s Tower – a vertical town that, at the same time, symbolizes human brotherhood. The idea is to build the facility consisting of four towers joined from above with an arch structure that has the same cross section as the towers. The building, thanks to the top arches, constitutes the symbol of the unity of south and north, east and west. Moreover, at the height of 900m there is a batten plate (thanks to which the building is 1200 m high) and the fifth component – the spherical structure with a diameter of 220 m. The outlines of the continents are placed on the elevation of the spherical structure. The whole building symbolizes the mankind that has taken under its wings the planet earth.

Strength of cold formed battened columns subjected to eccentric axial compressive force

The strength of a battened beam-column composed of four slender cold formed angles is mainly governed by the local buckling of its elements as well as the overall buckling of the column. The local buckling mode is mainly affected by local slenderness ratio of one angle (between batten plates). Overall buckling mode is mainly affected by overall member slenderness ratio as well as angle legs width to thickness ratio. Members' failure modes occur by local buckling and yielding at short lengths, and by local flexural buckling at intermediate and flexural at long lengths. In the present study, the behavior of bi-axially loaded battened beam-columns composed of four equal cold formed slender angles is investigated. A nonlinear finite element model was developed to study the effect of the aforementioned factors on the ultimate capacity of members. Geometrical and material nonlinearities were considered in the model. A parametric study was performed on a group of battened beam-columns with variable angle legs having different outstanding leg width–thickness ratios, angle local slenderness ratios, and column overall slenderness ratios. The axial–bending interaction curves are presented for short, medium and long beam-columns having two different square cross sections. These interaction curves were compared with different code rules. These design rules have been shown to be reliable using reliability analysis.

Nonlinear behaviour of built-up cold-formed steel section battened columns

This paper discusses nonlinear behaviour and design of built-up cold-formed steel section battened columns. The built-up columns were pin-ended and consisted of two cold-formed steel channels placed back-to-back and were connected using batten plates. Nonlinear 3-D finite element models were developed to simulate the structural performance of the axially loaded columns. The nonlinear material properties of flat and corner portions of the channels, initial geometric imperfections, actual geometries and boundary conditions were carefully considered in the models. The finite element models were verified against tests, recently conducted and reported by the authors, on the same form of construction. The column strengths, failure modes, deformed shapes at failure, load-lateral displacement and load-axial strain relationships were predicted from the finite element analyses and compared well against the test results. In addition, the validated finite element models were used to perform an extensive parametric study investigating different parameters affecting the behaviour of the columns comprising different slenderness, column lengths, cross-section geometries, steel strengths, spacing between channels and different batten plates spacing. Furthermore, the column strengths predicted in the parametric study were compared with design strengths calculated using the North American Specification, Australian/New Zealand Standard and European Code for cold-formed steel columns.

Experimental investigation of built-up cold-formed steel section battened columns

This paper presents an experimental investigation on behaviour and design of built-up cold-formed steel section battened columns. The built-up columns were pin-ended and consisted of two cold-formed steel channels placed back-to-back at varied spacing of intersection. The two channels were connected using batten plates, with varying longitudinal spacing. The cold-formed steel channel sections were manufactured by brake-pressing flat strips having a plate thickness of 2mm. The built-up cold-formed steel section battened columns had different slenderness and geometries but had the same nominal length of 2200mm. The column strengths, load–axial shortening, load–lateral displacement and load–axial strain relationships were measured in the tests. In addition, the failure modes and deformed shapes at failure were observed in the tests and reported in this paper. Overall, the built-up column tests provided valuable experimental data regarding the column behaviour that compensated the lack of information on this form of construction as well as used to develop nonlinear 3-D finite element models. The column strengths measured experimentally were compared against design strengths calculated using the North American Specification, Australian/New Zealand Standard and European Code for cold-formed steel columns. Generally, it is shown that the specifications were unconservative for the built-up cold-formed steel section battened columns failing mainly by local buckling, while the specifications were conservative for the built-up columns failing mainly by elastic flexural buckling.

Investigation on the behaviour and strength of cold-formed steel web stiffened built-up battened columns

Cold-formed steel built-up sections are commonly used as compression elements to carry larger loads and over longer spans when a single individual section is insufficient. This paper reports a numerical study of the cold-formed steel built-up web stiffened lipped channel sections under axial compression. The built-up sections are formed by two identical lipped channels placed back to back with batten plates and are connected by self-driving screw. The Finite element model is developed by ABAQUS software and the model is validated with the results available in the literature. Three types of web stiffened lipped channel cross section have been chosen for the study, based on the AISI-S100:2007 Geometric limitations. The parametric study is extended by the validated model for various slenderness ratios. The column strength predicted by the finite element analysis is compared with the design column strengths predicted by direct strength method (DSM). Based on this study a recommendation is proposed to DSM.

Behavior of reinforced concrete columns strengthened by steel jacket

RC columns often need strengthening to increase their capacity to sustain the applied load. This research investigates the behavior of RC columns strengthened using steel jacket technique. Three variables were considered; shape of main strengthening system (using angles, C-sections and plates), size and number of batten plates. Behavior and failure load of the strengthened columns were experimentally investigated on seven specimens divided into two un-strengthened specimen and five strengthened ones. A finite element model was developed to study the behavior of these columns. The model was verified and tuned using the experimental results. The research demonstrated that the different strengthening schemes have a major impact on the column capacity. The size of the batten plates had significant effect on the failure load for specimens strengthened with angles, whereas the number of batten plates was more effective for specimens strengthened with C-channels. Then, by using finite element (F.E) package ANSYS 12.0 [1] their behavior was investigated, analyzed and verified. Test result showed a good match between both experimental tests and F.E models.

Distortional Buckling Control of Cold-Formed Lipped Channel Columns with Web Stiffener

For cold-formed lipped channel columns with web stiffener, the distortional buckling stress may be lower than the local buckling and overall buckling stress, and thus it may control the design. A countermeasure to prevent the distortional buckling of such sections form happening by setting batten plates between two lips of the section was analyzed using the finite element program of ANSYS. Varying length and one way axial force eccentricity were concerned to observe the effect of the batten plates to the buckling behavior, load carrying capacities of the section in different cases. All the results can be the reference for later experimental study.

Out-of-Plane Stability Analysis of U-Section Pin-End Steel Arch

Two kinds of finite element model which can reflect the effects of different loading positions were constructed with Beam 188 and Shell 181. Effects of different restraints, load models and rise-span ratios on out-of-plane buckling were studied by comparing results of fixed arches with that of pin-end arches under three loading models. It is conservative to design by employing results of radial loading. As for out-of-plane stability, pin-end arches are better than fixed arches when rise-span ratio is big. Compared with U-section pin-end circular arches with diaphragm, those with batten plates have batter out-of-plane stability, and they are more economical and easier to construct.

Experimental study on seismic behavior of high-strength concrete filled double-steel-plate composite walls

In order to improve the ductility of the core wall in super high-rise buildings subjected to high axial compressive force and seismic effect, a new detailed concrete filled double-steel-plate (CFDSP) composite wall using high-strength concrete is proposed. This CFDSP composite wall is composed of concrete filled steel tubular columns at the two boundaries and concrete filled double-steel-plate wall body which is divided into several compartments by vertical stiffeners transversely connected by distributed batten plates. In order to intensively investigate the structural mechanism of this new type of CFDSP composite walls, twelve specimens are tested under large axial compressive force and reversed cyclic lateral load. No evident buckling of surface steel plates can be observed due to reasonable width-to-thickness ratios of steel plates and properly arranged batten plates, so that the surface steel plates and infill high-strength concrete can work compatibly in the whole loading process. All the specimens exhibited good energy dissipation ability and deformation capacity with full hysteretic curves and large ultimate drift ratios, thereby indicating that high-strength concrete can be used in seismic-resistant structures when the proposed new detailed walls are adopted. Based on the test results, the stiffness and strength degradations are analyzed, and the deformation characteristics of all the specimens are discussed in detail. Finally, a strength prediction approach based on the section analysis method is presented, and some detailing requirements for routine design practice are recommended.

Revision of Engesser’s Approach to the Problem of Euler Stability for Built-Up Columns with Batten Plates

Solving the buckling problem for a battened column as a statically indeterminate structure yields a Euler critical load that is significantly higher than the buckling load being obtained on the basis of Engesser’s assumption. The stability problem is reduced to numerically solving a two-point boundary value problem for a system of recurrence relations between deformation parameters of adjacent joint cross sections of the column. The expression of deformation parameters for each further joint cross section of the column as a linear function of deformation parameters for the preceding joint cross section is possible using the initial-value method. For columns with any degree of static indeterminacy, the critical force is determined as the smallest eigenvalue of the fourth-order system of homogeneous linear algebraic equations. A computer realization of the present method requires implementing reorthogonalization of the vectors of particular solutions for the system of recurrence relations. Plots of the buckling load for columns with any number of panels can be constructed as a function of the batten rigidity parameter. Applying these plots can be useful in selecting a cross section of the columns being designed.

Ultimate capacity of battened columns composed of four equal slender angles

Cold-formed steel structural members play a great role in modern steel structures due to their high strength and light weight. The behavior and strength of battened column members composed of slender angle sections are mainly governed by local buckling of angle legs or torsional buckling of the angle between batten plates. Moreover, local buckling depends on the interaction between the width–thickness ratio of angle leg, overall slenderness ratio of angle between batten plates and overall slenderness of column. Theoretical study has been carried out by a nonlinear material and geometrical finite element model. Numerous cases of slender battened column sections having different width–thickness angle leg ratios, overall slenderness ratios between batten plates and overall slenderness ratios are chosen in this study. Complete ultimate strength curves are drawn and different failure modes are studied by taking different member lengths, which produce local or torsional buckling of single angles between batten plates or overall buckling of the member. Empirical equations for the effect of shear deformation factor and the ultimate axial load capacities of members formed of battened slender angle sections are proposed. Strengths of axially loaded battened members predicted using finite element as well as the proposed empirical equations is compared with the design strengths obtained using North American and European codes. It is concluded that the design strengths predicted by North American and European codes are generally conservative, and these design rules have been shown to be reliable using reliability analysis.

Overall Stability of Open Cold-Formed Thin-Walled Steel Members with Hat Sections and Batten Plates under Axial Loads

Batten plates can play a significant role in reducing the bearing capacity of the entire component and preventing the upward warpage deformation in the opening section. The specific number of batten plates should be calculated for the open cold-formed thin-walled steel structure. By theoretical analysis, this study develops the flexural-torsional buckling formula for the open hat-section cold-formed thin-walled axially compressed members with batten plates. The calculating results show that, according to the configuration rule with 40 iy space between batten plates along the opening direction in the open thin-walled steel members, the warpage deformation will be effectively prevented in the opening direction. Besides, the bearing capacity of the entire member will be increased. The proposed calculation methods can actively complement the existing code.

Evaluation of Ayrton–Perry formula to predict the compressive strength of batten columns

This research was performed to evaluate two analytical methods for predicting the compressive strength of batten columns. Batten columns were subjected to pure axial compression, and the compressive strength was measured. The analytical methods used included the well-known Ayrton–Perry and ultimate strength curve methods to calculate the compressive strength of imperfect solid web columns, but their validity has not yet been studied experimentally on built-up columns. The geometrical parameters considered included the batten plate spacing and dimensions and the distance between the two longitudinal chords. The results show that the analytical methods were generally valid for the prediction of the compressive strength in batten columns and solid web columns. Using the average results of the Ayrton–Perry and ultimate strength curve methods leads to the best prediction of the column compressive strength. It was also shown that the initial imperfections in the batten columns could have a more important effect than the geometrical specifications on the value of compressive strength.

Overall Stability of Cold-Formed Steel Lipped Channel Axially Compressed Members with Batten Plates

Batten plates can play a significant role in reducing the bearing capacity of the entire component and preventing the upward warpage deformation in the opening section. The specific number of batten plates should be calculated for the open cold-formed thin-walled steel structure. By theoretical analysis, this study develops the flexural-torsional buckling formula for the open lipped-channel section cold-formed thin-walled axially compressed members with batten plates. The calculating results show that, according to the configuration rule with 80 iy space between batten plates along the opening direction in the open thin-walled steel members, the warpage deformation will be effectively prevented in the opening direction. Besides, the bearing capacity of the entire member will be increased. The proposed calculation methods can actively complement the existing code.

Stability of columns with semi-rigid connections including shear effects using Engesser, Haringx and Euler approaches

A complete column classification and the corresponding stability equations that can be used to evaluate the elastic critical axial loads of prismatic columns with sidesway uninhibited, partially inhibited, and totally inhibited including the simultaneous effects of bending and shear deformations and semi-rigid connections are presented and derived using three different approaches. The first two approaches are those by Engesser and Haringx that include the shear component of the applied axial force proportional to the total slope ( d y / d x ) and to the angle of rotation of the cross-section ( ψ ) along the member, respectively. The third approach is a simplified formulation based on the classical Euler theory that includes the effects of shear deformations but neglects the shear component of the applied axial force along the member. Comparisons among the critical loads obtained using these three approaches and those using the classical Euler solutions for classical column cases are presented. Examples that demonstrate the effectiveness and accuracy of the proposed stability equations and the importance of shear deformations and shear component of the applied axial force are presented in detail. These effects must be taken into account particularly in structures made of columns with relatively low effective shear areas A s (like laced columns, columns with batten plates or with perforated cover plates, and columns with open webs) or with low shear stiffness GA s of the same order of magnitude as π 2 E I / h 2 (like short columns made of laminated composites with low shear modulus G when compared to their elastic modulus E ). These effects become even more significant when the external supports are not perfectly clamped. The effects of semi-rigid connections and those due to shear forces and deformations are condensed into the proposed characteristic equations.