Design of Beams

tz, 1992

When designing a structure and its components, the designer must decide on the appropriate structural model. The choice of the model effects: • the analysis of the structure, which is aimed at the determination of the stress (internal forces and moments), and • the calculation of cross section resistance Thus a model implies the use of a method of analysis combined with a method of cross section resistance calculation. There are several possible combinations of methods of analysis and methods of cross-section calculation, for the ultimate limit state, involving either an elastic or plastic design approach; the possible combinations are: a) Plastic-plastic model: This is related to plastic design of structures. Full plasticity may be developed within cross-sections, so that plastic hinges can form. These have suitable moment rotation characteristics giving sufficient rotation capacity for the formation of a plastic mechanism, as the result of moment redistribution in the structure. b) Elastic-plastic model: For structures composed of sections which can achieve their plastic resistance, but have not sufficient rotation capacity to allow for a plastic mechanism in the structure. The stresses from the elastic analysis are compared with the plastic section capacity. c) Elastic-elastic model: When the cross section of a structure cannot achieve their plastic capacity both analysis and verification of cross section conducted elastically. Elastic analysis of reinforced concrete beams gives reasonable results up to working loads. Beyond working loads the elastic analysis is not applicable because of the non linearity in the stress-strain curves for the materials and the cracks which develop in concrete. When beam is loaded beyond working loads, plastic hinges form at certain locations. On further loading of the beam, bending moments do not increase beyond the ultimate moment capacities of the these sections, however, rotations at the plastic hinges keep on increasing. A redistribution of moments takes place, the moment now being received by the less stressed sections. The rotation at a plastic hinges keeps on increasing with out any increase in the moment until the ultimate rotation capacity is reached beyond which the section collapses 4.2 Non-Linear Analysis of Indeterminate Structures The linear elastic analysis of structures is based on the assumption that there is a linear relationship between the stress and strain in a member, i.e. Where: E is the elastic modulus (young's modulus) F 0 6 5 is strain

In plastic analysis and design of a structure, the ultimate load of the structure as a whole is regarded as the design criterion. The term plastic has occurred due to the fact that the ultimate load is found from the strength of steel in the plastic range. This method is rapid and provides a rational approach for the analysis of the structure. It also provides striking economy as regards the weight of steel since the sections required by this method are smaller in size than those required by the method of elastic analysis. Plastic analysis and design has its main application in the analysis and design of statically indeterminate framed structures.

In plastic analysis and design of a structure, the ultimate load of the structure as a whole is regarded as the design criterion. The term plastic has occurred due to the fact that the ultimate load is found from the strength of steel in the plastic range. This method is rapid and provides a rational approach for the analysis of the structure. It also provides striking economy as regards the weight of steel since the sections required by this method are smaller in size than those required by the method of elastic analysis. Plastic analysis and design has its main application in the analysis and design of statically indeterminate framed structures.

International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022

There are many situations in which the I-Sections used in construction are subjected to moments about their weaker axis, i.e. the y-y axis. For such purposes the Plastic Section Modulus about y-y axis becomes necessary. In the present paper an attempt has been made to calculate and present the values of Z py , for I.S. Rolled Steel Beam Sections (with tapered flanges). Since IS 800 : 2007 [2] has not given the values of Z py , of any section, one tapered flange I-Section, viz., 125 TFB @ 13.1 kg/m, from "Onesteel" (Australia), [4] has been used to ascertain the correctness of calculations. The results are presented in table form in descending order.

Innovative Infrastructure Solutions, 2018

In this research, a suggested linear model was investigated to analyze the plastic stage for indeterminate skeletal steel structures. The aim of this model is to facilitate the analysis of the structure element in the plastic stage without resorting to the complicated calculations of the material nonlinearity. The suggested model was represented by considering the full plastic sections in the element as a concentrated plastic hinge. The plastic hinge was modeled instead of the plastic zones as a pin support or an intermediate hinge with a rotational spring. Computing the stiffness of rotational spring was based on the acceptance criteria in the nonlinear static analysis according to FEMA 356 (2000). The linear structural methods can be used after that to calculate the deformations and moments in plastic stage. In this paper and due to the simple cases which are analyzed, the forced method of structural analysis can be used. But for structural elements which are more complicated than the present cases where the plastic hinges are separated on more positions, the finite element analysis is the best. The suggested model can be used to predict the mechanism of failure, to evaluate the deformations after occurring the plastic moment as well as to compute the elastic redistribution moments. The suggested model was verified by comparing the experimentally and analytically results of steel beam deformations which made by El Damatty (J Steel Compos Struct 3:421-438, 2003) with the obtained results of the suggested model, and the suggested model gave good results. Moreover, a W-shaped fixed steel beam was analyzed by finite element method by using ANSYS program, the suggested model and elastic analysis to compute the induced moments in plastic stage and evaluated the elastic redistribution moments. The suggested model gave matching values of the induced moments of the fixed compared with the finite element results.

In plastic analysis and design of a structure, the ultimate load of the structure as a whole is regarded as the design criterion. The term plastic has occurred due to the fact that the ultimate load is found from the strength of steel in the plastic range. This method is rapid and provides a rational approach for the analysis of the structure. It also provides striking economy as regards the weight of steel since the sections required by this method are smaller in size than those required by the method of elastic analysis. Plastic analysis and design has its main application in the analysis and design of statically indeterminate framed structures.