Investigation on the influence of point loads on the deflection behaviour of G+5 frame structure

Nowadays, multi-storey structure portal frames are most commonly used worldwide. Multistory frames are used in structural systems in all metropolitan cities, future cities, and important businesses. The present study the effect of various point loads varying from 22 to 32 kN in steps of 2 were applied on the center of horizontal beams of the frame structure. The deflection behaviour in form of deflection, reaction, beading moments under point loading were discussed analytically according to stiffness matrix method and the results are validated with the help of simulation using STAAD Pro software. Results revealed that the analytical method using manual calculations in excel sheet provides approximately similar results as obtained by the costly simulation technique using STAAD Pro software. Therefore, the implementation of this excel sheet can be recommended for standard analysis of portal frame structures based on the outcomes of this study.

Numerical and Experimental Analysis of Timber Portal Frame with Semi-Rigid Knee Joints

The problems related to development of rotational deformations of a knee joints and crack propagation in rafter elements of timber portal frames were discussed in this article. The rotational displacement, which develops between the rafter and column members due to the bending deformations of the bolts in the knee joint with a simultaneous embedment into the wood, increases the global deformations of the portal frame. Additionally, to axial force and bending moment the rafter elements are heavily loaded with shear force at the sections near knee joint especially. All effects together create very complicated complex of affecting factors. In the current study the design methodology of timber portal frames has been revised with the purpose to develop a more comprehensive set of design conditions for timber portal frames with dowel type fasteners in the knee joints. It is suggested to use the Hoffman failure criterion taking into account the difference of strength in tension and compression to manage the effects of plastic yielding combined with the crack development in wood assumed it as an orthotropic material. It has been proved by case studies of timber portal frames under service loads, as well as by tests and theoretical considerations. The set of design conditions must be supplement by additional clauses comprising Hoffman failure criterion regarding timber sections heavily loaded in shear and cross grain tension. Also, it is recommended that the design capacity of dowel type fastener should be decreased when shear force transferred by the bolt acts perpendicular to the grain direction inducing tension cross grain direction. Other measure may be application of some surface strengthening method.

Optimization of Bolted Connection in Steel Corbel Attach to RC Column of MRT Viaduct

MRT is one of the backbones of a city’s public transportation system, capable of carrying large crowds. The use of a portal frame in the design of an MRT train station has raised significant concerns about how the portal frame’s load will be supported by the extended structure element known as a corbel. A corbel is a protruding structural element that supports weights like primary beams and girders. Engineers must then decide how to properly bolt the steel corbel structure to the concrete pier segment or columns. Generally, most corbel structure designs were constructed of concrete; however, in this study corbel design was made of steel so that the steel portal frame could rest on the corbel structure, allowing for more usable area on the platform, such as kiosks and other amenities. Optimization of end plate thickness and beam web thickness is carried out. Manual calculations are used in addition to FEA modeling to examine the bolt’s deflection, shear, bearing, tension, slip, and block tearing resistance. When using Eurocode, all three loadings, transverse force, vertical force, and transverse moment, produce values that are 10% lower than the British Standard. As a result, designers can optimize their designs using Eurocode.

APPLICATION OF GRADIENT PROJECTION METHOD TO PARAMETRIC OPTIMIZATION OF STEEL LATTICE PORTAL FRAME

The paper has proposed a mathematical model for parametric optimization problem of the steel lattice portal frame. The design variable vector includes geometrical parameters of the structure (node coordinates), as well as cross-sectional dimensions of the structural members. The system of constraints covers load-carrying capacities constraints formulated for all design sections of structural members of the steel structure subjected to all ultimate load case combinations. The displacements constraints formulated for the specifiednodes of the steel structure subjected to all serviceability load case combinations have been also included into the system of constraints. Additional requirements in the form of constraints on lower and upper values of the design variables, constraints on permissible minimal thicknesses, constraints on permissible maximum diameter-to-thickness ratio for the structural members with circle hollow sections, as well as the conditions for designing gusset-less welded joints between structural members with circle hollow sections have been also considered in the scope of the mathematical model. The method of the objective function gradient projection onto the active constraints surface with simultaneous correction of the constraints violations has been used to solve the formulated parametric optimization problem. New optimal layouts of the steel lattice portal frame by the criterion of the minimum weight, as well as minimum costs on manufacturing and erection have been presented.