On Structural Redundancy in Space Trusses

1988 ◽  
Vol 3 (4) ◽  
pp. 237-241 ◽  
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.

scholarly journals Starred angles supporting secondary trusses

1991 ◽  
Vol 18 (1) ◽  
pp. 118-129
Author(s):  
Murray C. Temple ◽  
Kenneth Hon-Wa Mok
Keyword(s):  
Cross Section ◽  
Carrying Capacity ◽  
Slenderness Ratio ◽  
The Other ◽  
Load Carrying Capacity ◽  
Industrial Buildings ◽  
Compression Members ◽  
Load Carrying ◽  
Structural Connections ◽  
Open Nature

In some large industrial buildings, it is common to span large areas by using primary trusses in one direction and secondary trusses in the other. The secondary trusses frame into the vertical web members in the primary trusses. Starred angles are frequently used as the vertical web members in the primary trusses because of their symmetrical cross section and the ease with which the connections can be made. These starred angles are usually designed as axially loaded members, but the open nature of the cross section and the fact that the secondary truss frames into one of the angles has raised some doubts about this loading assumption. As a result of this concern, an experimental research program was undertaken to investigate the behaviour and strength of starred angle web members supporting secondary trusses. The results obtained indicate that these starred angle compression members are not concentrically loaded, as the stress distribution across the angles is not uniform. It was found that if the slenderness ratio is modified in accordance with the requirements of ASCE Manual 52, the load-carrying capacity of the starred angles supporting secondary trusses can be determined using Clause 13.3.1 of CAN3-S16.1-M84. Key words: angles (starred), buckling, columns (structural), connections, trusses.

Experimental Study for Single-Angle Beam-Column Members Attached by one Leg

2010 ◽  
Vol 163-167 ◽  
pp. 433-438
Author(s):  
Xian Lei Cao ◽  
Ji Ping Hao ◽  
Chun Lei Fan
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Carrying Capacity ◽  
Model Experiment ◽  
Ultimate Load ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Compression Members ◽  
Load Carrying ◽  
Ultimate Load Carrying Capacity

To obtain a better understanding of the behavior and load-carrying capacity of Q460 high-strength single-angle compression members bolted by one leg, using static loading way to 48 angles carried out experimental study. The experiments show test specimens produce biaxial bending, most small slenderness ratio members are controlled by local buckling, and slender specimens are controlled by overall buckling. In addition to these factors in model experiment, influences of residual stresses on ultimate load-carrying capacity were analyzed by finite element numerical simulation analysis, the results show the residual stresses affect the ultimate load-carrying capacity of angles by about 5％ or less. Comparison of the load-carrying capacity of experimental and theoretical results indicate the difference of experimental and finite element values ranges from -9.99％ to +9.76％, American Design of Latticed Steel Transmission Structure (ASCE10-1997) and Chinese Code for Design of Steel Structures (GB50017-2003) underestimate separately the experimental load-carrying capacity by about 2.34％～33.93％ and 1.18％～63.3％, and the agreement is somewhat good between experimental program and the finite element analysis. Based on model experiment and simulated experiment, the formula of stability coefficient of single-angle compression members was established. It provides basic data for spreading Q460 high-strength single-angles members attached by one leg.

Analysis of Load-Carrying Capacity of Thin-Walled Closed Beams with Different Slenderness

2014 ◽  
Vol 969 ◽  
pp. 39-44
Author(s):  
Jan Valeš
Keyword(s):  
Cross Section ◽  
Carrying Capacity ◽  
Random Fields ◽  
Capacity Analysis ◽  
Geometrically Nonlinear ◽  
Load Carrying Capacity ◽  
Design Load ◽  
Steel Members ◽  
Load Carrying ◽  
Thin Walled

The presented paper deals with the load-carrying capacity analysis of compress steel members having the square closed (box) cross-section with non-dimensional slenderness 0.6, 0.8, 1.0 a 1.2. The axis of these beams is randomly three-dimensionally curved. Initial curvatures are modelled by random fields applying the LHS method. Load-carrying capacities are then calculated by the geometrically nonlinear solution using the ANSYS program. The results are presented both in form of histograms and of the table. The analysis of load-carrying capacity of beams with individual nonlinear slenderness is carried out, and the values are compared with the values of design load-carrying capacity according to the standard.

Single-angle compression members welded by one leg to a gusset plate. II. A parametric study and design equation

1998 ◽  
Vol 25 (3) ◽  
pp. 585-594 ◽  
Author(s):  
Murray C Temple ◽  
Sherief SS Sakla
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Design Equation ◽  
Rigid Support ◽  
The Finite Element Method ◽  
Gusset Plate ◽  
Compression Members ◽  
Load Carrying

Single-angle compression members are complex members to analyze and design. The two generally accepted design procedures, the simple-column and the beam-column approaches, in general, underestimate the load-carrying capacity of single-angle compression members welded by one leg to a gusset plate fixed to a rigid support. One of the reasons is that these approaches do not properly account for the end constraint provided by the gusset plate. The effective length factor can be adjusted, but this is difficult to do as the end restraint is not easy to evaluate in many practical cases. Another reason is that these approaches are not based on a rational understanding of the failure mechanism of these members. An experimental program confirmed that the finite element method can be used, with a reasonable degree of accuracy, to predict the behavior and load-carrying capacity of single-angle compression members welded by one leg to a gusset plate fixed to a rigid support. The finite element method was used to study some 1800 different combinations of parameters. It was found that out-of-straightness, residual stresses in the angle section, Young's modulus of elasticity, and the unconnected gusset plate length do not have a great effect on the load-carrying capacity. The most significant parameter is the gusset plate thickness with the gusset plate width being the second most important parameter. An empirical design equation is proposed.Key words: angles, buckling, columns (structural), compressive resistance, design equation, gusset plates.

scholarly journals Influence of executive imperfections of railway steel bridges construction on operational capacity and fatigue capacity

2013 ◽  
Vol 12 (2) ◽  
pp. 071-078
Author(s):  
Adam Wysokowski
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
Steel Bridges ◽  
Load Carrying Capacity ◽  
Bridge Structure ◽  
Geometric Imperfections ◽  
Theoretical Methods ◽  
Critical Elements ◽  
Load Carrying ◽  
Operational Capacity

In recent years, in our country are modernized and rebuilt several sections of railway lines, mainly main lines. The greater part is adapted to increased speeds. However, such an adaptation involve the reconstruction or construction of new bridges including steel ones. The paper concerns the executive imperfections of constructions of steel bridges which in recent years have been built in the modernized main railway lines. These imperfections consist of, among others, the geometric imperfections from the assumed construction project. This also applies to defects in welds of various types that occur in critical elements of bridge structure. The aim of this paper is to demonstrate the influence of imperfections on the load carrying capacity and fatigue of these structures. Author showed that the observed imperfections have a significant impact on the fatigue life - especially for weld defects, in the case of load carrying capacity their importance is much smaller. These analyses are performed by using the theoretical methods developed in previous reports. In the analysis new standards for the design of steel structures from Eurocodes group were used.

Design load-carrying capacity estimates and an improved wooden shore setup

2004 ◽  
Vol 17 (2) ◽  
pp. 167-186 ◽  
Author(s):  
Y.L. Huang ◽  
Y.C. Lin ◽  
C.F. Lee ◽  
H.J. Chen ◽  
T. Yen
Keyword(s):  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Design Load ◽  
Load Carrying ◽  
Capacity Estimates

scholarly journals Balanced and unbalanced welds for angle compression members

1994 ◽  
Vol 21 (3) ◽  
pp. 396-403 ◽  
Author(s):  
Murray C. Temple ◽  
Sherief S. S. Sakla
Keyword(s):  
Key Words ◽  
Carrying Capacity ◽  
Compressive Load ◽  
Tensile Load ◽  
Effective Length ◽  
Load Carrying Capacity ◽  
Compression Members ◽  
Load Carrying ◽  
Compressive Loads ◽  
Compressive Resistance

Angles used as web members in trusses are often welded to the chords with unbalanced welds. This is necessary because of space limitations. It is not known what effect such a weld has on the compressive load carrying capacity of an angle. The standards and specification examined allow an unbalanced weld for an angle. The justification for using such a weld is based on research conducted on angles in tension. For these members, it was concluded that an unbalanced weld does not affect the tensile load carrying capacity of the angle. Research results for angles with different weld patterns subjected to compressive loads are not available in the literature. Eighteen tests were conducted on angle compression members with various weld patterns. It was determined that an unbalanced weld is detrimental to the load carrying capacity of an intermediate length angle but is beneficial for a slender angle. Key words: angles, column (structural), compressive resistance, effective length, standards, welds.

scholarly journals Simplified Reliability Estimation for Optimum Strengthening Ratio of 30-Year-Old Double T-Beam Railway Bridge by NSM Techniques

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Minkwan Ju ◽  
Hongseob Oh ◽  
Jong-Wan Sun
Keyword(s):  
Carrying Capacity ◽  
Design Methodology ◽  
Reliability Estimation ◽  
Load Carrying Capacity ◽  
Railway Bridge ◽  
Structural Redundancy ◽  
Nominal Property ◽  
Load Carrying ◽  
Cfrp Strip ◽  
T Beam

This study is to develop simplified reliability estimation for optimum strengthening ratio of T-beam railway bridge strengthened by CFRP strip. Until now, strengthening design has been usually proceeded to satisfy the target load-carrying capacity by using the deterministic parameter of nominal property for concrete or FRP. For the optimum strengthening design, however, it is required that reliability-based strengthening design should be applied to effectively determine the amount of strengthening material and make sure of the safety of the structure. As applying the reliability-based strengthening ratio, more reliable strengthening design using CFRP strip is possible as well as having a structural redundancy. The reliability-based strengthening design methodology suggested in this study is able to contribute the optimum strengthening design for a concrete structure strengthened by CFRP strip.

Polymer Composite with Sisal Fiber Used for Node Reinforce in Space-Truss with Stamped Connection

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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