Structural Steel Framework Research Articles

A Novel 3-D Embedded Module for Displacement Measurement in Metal Structures

Measurements of relative displacement between the components of structural steel frameworks such as those used in large buildings, bridges, ships, and offshore platforms can be used to detect overstress or impending failure. However, current approaches used to measure displacement require complex arrays of optical sensors or strain gauges. We instead present a novel low-cost wireless 3-D embedded module that uses inductive eddy-current sensing with planar printed circuit board (PCB) coils to measure relative displacement between two or more metal plates. The module is a 50-mm cube with four faces formed by the planar PCB inductors that are used for measurement of relative displacement. The other faces and the hollow center of the cube are used for a four-channel inductive sensing IC, a microcontroller with integrated 802.15.4-compatible radio, antenna, micro-USB serial connector, battery, and battery charger/monitor. The addition of temperature and humidity sensors and a microelectromechanical system inertial measurement unit makes the module into a full structural health monitoring system that can also sense environmental factors, inclination, vibration, and shock. The module was evaluated in two axes in a custom test system that allowed controlled relative movement to two orthogonal mild steel plates, as well as inclination of the plate in a different test setup. The results show that a resolution of 0.5 mm can be achieved in both axes when measuring displacement from the planar coils to the steel plates, with negligible interference between coils/plates on the adjacent faces. The displacement measurement is immune to the presence of water between the planar inductors and the steel plates, allowing the module to be used in applications exposed to high humidity and rain.

Modeling and FE analysis of column to beam end-plate bolted connection

Article history: Received September 20, 2013 Received in Revised form October, 14, 2013 Accepted 25 November 2013 Available online 26 November 2013 This piece of work aims at the modeling and using the finite element method approach (FEM) to analyze the fatigue behavior of bolted beam to column end-plate connection in the structural steel framework subjected to static loading. A detailed three dimensional (3D) simulation model of the bolted beam to column end-plate connection is constructed in PRO-E wildfire and it is analyzed in the ANSYS workbench to obtain its behavior. The bolted end-plate connection is chosen as an important type of beam to column joint. The end-plate connection is chosen for its complexity in the analysis and behavior due to the number of connection components and their inheritable behavior. The solid elements, bonded contact and the bolt pretension are included to obtain the behavior of the structure. The FEA results of the structure with or without bolt pretension are compared with the available literature. At last the fatigue behavior of connections under over tensioning is presented in this work. © 2013 Growing Science Ltd. All rights reserved.

Probabilistic Performance-Based Optimal Design of Steel Moment-Resisting Frames. I: Formulation

Significant progress has been made in the preceding two decades in the area of seismic engineering. Design codes are very quickly migrating from prescriptive procedures intended to preserve life safety to reliability-based design with less prescription intended to quantify risk associated with designs. Therefore, all stakeholders are given the opportunity to speak a common language probability and risk leading to structural designs that not only reliably preserve life safety after rare ground motions, but minimize damage after more frequent ground motions and thereby minimize life-cycle costs. Probabilistic performance-based design is in between traditional prescrip- tive design methods and full reliability-based design methodologies. The present paper provides an overview of a state-of-the-art model- code performance-based design methodology and casts this design procedure into multiple-objective optimization problems for single- story and multistory structural steel frameworks with fully and partially restrained connections. A methodology for applying an evolutionary genetic algorithm with radial fitness and balanced fitness functions is discussed in detail. A companion paper provides applications of the automated design algorithm to single-story frames and multistory frames with a variety of connection characteristics and beam-to-column moment capacity ratios. DOI: 10.1061/ASCE0733-94452007133:6757 CE Database subject headings: Seismic design; Nonlinear analysis; Connections, semi-rigid; Evolutionary computation; Optimization; Algorithms; Probabilistic methods; Inelastic action.

RHS beam-to-column connection with web opening—experimental study and finite element modelling

Rectangular Hollow Sections (RHS) have superior structural performance compared to conventional steel sections. However, the application of RHS in structural steel framework is limited because suitable connection configurations have not been developed between such members. Also adequate information on the moment–rotation characteristics of connections between RHS members is not available for design. To overcome these problems, a new and efficient connection is proposed which is easy to fabricate and convenient for erection. The connection employs channel connectors welded to the column flange and bolted to the beam to transfer beam flange forces into the column webs thereby avoiding the need to provide internal diaphragms in the column. An opening in the web facilitates the installation of bolts and can be used to pass service lines. The bolts are loaded in shear, so as to obtain improved performance of the connection under cyclic loading. By choosing suitable dimensions for the channel connectors, the strength and stiffness of the connection can be varied. The behaviour of the connection is evaluated by cyclic tests and non-linear finite element analysis. Test results are presented in the form of hysteretic curves and failure modes. In the case of channel connectors of high strength, failure occurs at the beam net section away from the face of the column, similar to beams with Reduced Beam Sections (RBS). It is shown that the connection has adequate ductility and hysteretic energy dissipation capacity. The moment–rotation characteristics of the connection can be expressed in terms of the three-parameter power model, for semi-rigid frame analysis.

Manchester United FC new North Stand

This paper describes the design and construction of the new North Stand at Manchester United Football Club. Watson Steel Limited was responsible for the design and construction of the structural steel framework to a brief prepared by architect Atherden-Fuller and consulting engineer Campbell Reith Hill. The overall management of the construction was undertaken by Hilstone Laurie, which also acted as planning supervisor and principal contractor in relation to the recently introduced CDM Regulations.

Inelastic Behavior of Multistory Partially Restrained Steel Frames. Part II

The plastic-zone method of analysis described in a companion paper is used in the inelastic analysis of three multistory, multibay fully restrained (FR) and partially restrained (PR) steel frames. Full nonlinear load-deformation response, including the ultimate load and unloading path is computed. The state of connection stiffness and connection rotation at the frame ultimate load condition is discussed, and the spread of yielding within a large-scale steel frame is described in detail. The effect of loading sequence on the ultimate load capacity of FR and PR structural steel frameworks is discussed. Several of the proposed connection classification systems are evaluated within the context of the frames analyzed and designed.

Industrial system grounding for power, static, lightning, and instrumentation, practical applications

Practically every structural steel building erected for industrial use incorporates reinforcing steel bars installed in the concrete footings. This, without any additional effort, constitutes a grounding electrode. The quantity of electrodes is directly related to the building area. When the structural steel framework is erected and interconnected, these electrodes are also interconnected in a parallel arrangement. Similarly, high-voltage metal transmission towers are installed using a metal footing base embedded in a concrete filled hole. The four tower legs are effectively in parallel and offer an adequate low ground resistance such that additional electrodes are generally not required. This brings us to the main point: the reinforced concrete footings, reinforced concrete grade beams, and other reinforced concrete structures provide, with a little work, an effective, reliable, and cost attractive system grounding vehicle.

Nonlinear analysis of frames with member unloading

A nonlinear, collapse load analysis that can easily be used to model and accurately predict failure load of braced, structural steel frameworks is formulated. The methodology considers member post-failure, inelastic unloading due to instability, excessive deformation and yielding without placing restrictions on frame size, geometry, or member stress-strain relationships. The loading is so incremented that each load level corresponds to the occurrence of an event, such as formation of a plastic hinge or member instability, and to obtain the correct equilibrium configuration up to collapse, the complete incremental loading history of the structure is taken into account. Moreover, convergence complications associated with limit point instability analyses are avoided, as member-structure deformation compatibility relations are developed and utilized in evaluating member forces from member post-buckling force equilibrium conditions. Illustrative examples are provided to demonstrate the effects of element failure and of bracing system on frame capacity. Lastly, conclusions are drawn as to when a nonlinear analysis beyond bracing failure is warranted and how member unloading affects overall collapse.

Optimal design of structural steel frameworks

This paper reviews work conducted at the University of Waterloo during the 1980s concerning the computer-automated design of least-weight structural steel frameworks. First, design under static loads is considered whereby the members of the structure are automatically sized using commercial steel sections in full conformance with design standard provisions for elastic strength/stability and stiffness. This problem is illustrated for the least-weight design of a steel mill crane framework comprised of a variety of member types and subject to a number of load effects. Then, the design methodology is extended to the least-weight design of structural steel frameworks under both service and ultimate loading conditions. Here, acceptable elastic stresses and displacements are ensured at the service-load level while, simultaneously, adequate safety against plastic collapse is ensured at the ultimate-load level. This design problem is illustrated for the least-weight design of an industrial steel mill framework for which plastic behaviour is governed by conservative piecewise linear yield conditions. Finally, the computer-based design methodology is extended to the least-weight design of structural steel frameworks subjected to dynamic loading. Constraints are placed on dynamic displacements, dynamic stresses, natural frequencies and member sizes. The design problem is illustrated for the least-weight design of a steel trussed arch subjected to non-structural masses and an impulse force.

Microcomputer‐Based Optimization of Steel Structures in Professional Practice

The paper concerns the computer‐automated design of least‐weight structural steel frameworks, where members are automatically sized using commercial standard steel sections in full conformance with steel design code provisions for strength/stability and stiffness. The necessary features and functions of such a design system are first identified. Two alternative approaches to the optimal design of steel frameworks are then discussed. Finally, a microcomputer software system is applied for the least‐weight design of a steel framework comprised of a variety of member types and subject to a number of load effects. A number of alternative designs of the framework are conducted to illustrate differing optimization strategies and corresponding outcomes.

Macpherson metal primer used for steel fabricators own building

Macpherson's zinc phosphate high performance metal primer has been used by steel fabricators SCWS Limited of Dereham, Norfolk, to protect the structural steel framework of their new works extension.

Strength of I-Beams in Combined Bending and Torsion

In the design of a structural steel framework it is considered good practice to avoid subjecting I-beams to the combined effect of bending and torsion, because the torsional resistance of I-beams is usually low. It is often easy to determine a layout in which torsion is either entirely eliminated or greatly reduced. Sometimes, however, this is impracticable or impossible, and cases exist where beams carry eccentric loads and are therefore stressed in both bending and torsion. Laterally unsupported building spandrels offer a common · example. Also, it is often impossible to avoid eccentricity of loads on beams in industrial structures because of the extreme complexity of the equipment they are designed to support. In these, and numerous other cases, the designer is called on to investigate stresses in I-beams loaded in combined bending and torsion.