22. Load-carrying capacity of space trusses under the influence of imperfections

2015 ◽

Vol 719-720 ◽

pp. 202-205

Author(s):

Cleirton A.S. Freitas ◽

Mucio M.S. Nobrega ◽

Édipo A. Bezerra ◽

Otávio R.O. Cavalcante

Keyword(s):

Polymer Composite ◽

Carrying Capacity ◽

Three Dimensional ◽

Sisal Fiber ◽

Load Carrying Capacity ◽

Space Truss ◽

Load Carrying ◽

Steel Bars ◽

Space Trusses

Space trusses are three-dimensional structures made of steel bars very frequently used at the roof construction. The bars, with tubular section, are linking in the 3D form by connections. There are several types of connections to attach these members. The most economical connection is the staking end-flattened connection, also called typical node. The reduced cost and the fast assemblage of the truss are among their advantages. However, such connections present disadvantages like eccentricities and stiffness weakening of the tubular members. This research presents suggestions of reinforcement and constructive correction in the connection in order to increase its capacity. The base for this is the reduction of the eccentricity in typical node applying the spacer. This spacer was made by polymer composite with sisal fiber. In this work was developed experimental lab tests in prototypes with fifty four meters square of area. The results show an increase of 26% for collapse in the truss load carrying capacity when the suggested changes proposed in this article are used for the staking end-flattened connections.

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Strengthening Space Trusses by Diagonal Removal

International Journal of Space Structures ◽

10.1177/026635119300800401 ◽

1993 ◽

Vol 8 (4) ◽

pp. 231-239 ◽

Cited By ~ 4

Author(s):

Mousa Tabatabaei ◽

Cedric Marsh

Keyword(s):

Carrying Capacity ◽

Load Capacity ◽

Maximum Load ◽

Load Carrying Capacity ◽

Shear Forces ◽

Equitable Distribution ◽

Space Truss ◽

Load Carrying ◽

Space Trusses ◽

Selection Of

Ideally a space truss is composed of bars each of which is suited to the load it carries. In practice, however, it is more convenient to use a limited number of bar sizes, thus only a few of the members will be fully stressed when the maximum load capacity of the space truss is reached. In order to effect a more equitable distribution of forces between chords of equal size such that more chord members are loaded close to their capacity, selected diagonals are removed to control the path followed by the shear forces, and thereby control the forces entering the chords. In this paper the effect of diagonal removal on space trusses is demonstrated and a method for selection of the diagonals whose removal gives optimum increase in the load carrying capacity of a space truss is described.

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On Structural Redundancy in Space Trusses

International Journal of Space Structures ◽

10.1177/026635118800300405 ◽

1988 ◽

Vol 3 (4) ◽

pp. 237-241 ◽

Cited By ~ 8

Author(s):

Ariel Hanaor ◽

An-Fu Ong

Keyword(s):

Carrying Capacity ◽

Collapse Mechanism ◽

Load Carrying Capacity ◽

Allowable Stress ◽

Structural Redundancy ◽

Critical Elements ◽

Design Load ◽

Compression Members ◽

Load Carrying ◽

Space Trusses

Static redundancy does not ensure structural redundancy in cases where the collapse mechanism involves instability. Structural redundancy is defined here as the ability of the structure to sustain its design load with the loss of one or more critical elements. The parametric investigations on a square on square double-layer grid presented here, suggests that the loss of one critical member from this type of structure typically entails a loss of 20% to 30% of load carrying capacity. To allow for structural redundancy, as well as for loss of carrying capacity due to the effect of imperfections, it is recommended to reduce compression members' buckling (or allowable) stress by a corresponding value or, alternatively, to perform a suitable analysis.

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Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2005.10.2.15129 ◽

2005 ◽

Vol 10 (2) ◽

pp. 151-160 ◽

Cited By ~ 3

Author(s):

J. Kala ◽

Z. Kala

Keyword(s):

Yield Strength ◽

Cross Section ◽

Carrying Capacity ◽

Bending Moment ◽

Statistical Characteristics ◽

Load Carrying Capacity ◽

Load Carrying ◽

Strength Variability ◽

Hot Rolled ◽

Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

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Fuzzy Sets Theory in Comparison with Stochastic Methods to Analyse Nonlinear Behaviour of a Steel Member under Compression

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2005.10.1.15135 ◽

2005 ◽

Vol 10 (1) ◽

pp. 65-75 ◽

Cited By ~ 5

Author(s):

Z. Kala

Keyword(s):

Fuzzy Sets ◽

Carrying Capacity ◽

Stochastic Methods ◽

Nonlinear Behaviour ◽

Load Carrying Capacity ◽

Load Carrying ◽

Input Parameters ◽

Stochastic Solution ◽

Fuzzy Solution ◽

Sets Theory

The load-carrying capacity of the member with imperfections under axial compression is analysed in the present paper. The study is divided into two parts: (i) in the first one, the input parameters are considered to be random numbers (with distribution of probability functions obtained from experimental results and/or tolerance standard), while (ii) in the other one, the input parameters are considered to be fuzzy numbers (with membership functions). The load-carrying capacity was calculated by geometrical nonlinear solution of a beam by means of the finite element method. In the case (ii), the membership function was determined by applying the fuzzy sets, whereas in the case (i), the distribution probability function of load-carrying capacity was determined. For (i) stochastic solution, the numerical simulation Monte Carlo method was applied, whereas for (ii) fuzzy solution, the method of the so-called α cuts was applied. The design load-carrying capacity was determined according to the EC3 and EN1990 standards. The results of the fuzzy, stochastic and deterministic analyses are compared in the concluding part of the paper.

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Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

Tire Science and Technology ◽

10.2346/1.2174344 ◽

2005 ◽

Vol 33 (4) ◽

pp. 210-226 ◽

Cited By ~ 6

Author(s):

I. L. Al-Qadi ◽

M. A. Elseifi ◽

P. J. Yoo ◽

I. Janajreh

Keyword(s):

Carrying Capacity ◽

Material Properties ◽

Three Dimensional ◽

Fe Analysis ◽

Load Carrying Capacity ◽

Inflation Pressure ◽

3D Finite Element ◽

Load Carrying ◽

Pavement Damage ◽

New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

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