Miroslav Škaloud

The effect of shear lag in the light of various definitions of the ultimate limit state of stiffened compression flanges

Abstract The effect of shear lag, combined with plate buckling, in longitudinally stiffened compression flanges is studied via two plastic and one elastic definitions of the ultimate limit state. An analysis of the obtained results reveals that if the ultimate limit state of the compression flanges is defined by means of a plastic approach, the effect of shear lag can be completely disregarded, this also confirming the approach of the new British Design Code 5 400. However, if the ultimate limit state is based on quasi-elastic considerations, the influence of shear lag can be pronounced and, consequently, needs to be taken into account.

Experimental research on the ultimate load behaviour of steel plated structures

Abstract The paper describes the main results of two experimental investigations into the ultimate load behaviour of steel plated structures. The first is concerned with the performance of the longitudinally stiffened compression flanges of steel box girder bridges and reports tests on 12 large-scale girders. On the basis of an analysis of the progression of plastification in the girder, two criteria for the definition of the ultimate limit state of longitudinally stiffened compression flanges are put forward. The other study focuses on the behaviour of longitudinally stiffened webs under the action of partial edge loading. The results of 152 tests are analysed, and the effect of (i) the position and (ii) the size of the longitudinal rib on the ultimate load behaviour of the webs is studied.

Large Deflections of Slender Webs Fitted with Ribs

While in Chapter 7 we investigated the post-buckled behaviour of plates by means of an orthotropic plate concept, i.e. all stiffeners being smeared over the plate surface, this chapter is going to study the post-critical performance of stiffened webs as these actually behave, i.e. as a system of web sheet and discrete stiffeners.

Large Deflections of Elasto-Plastic Webs

The webs of steel structures present unavoidable initial deviations from the ideal state and, moreover, residual stresses occur in them.

Problems of Solution of a System of Non-Linear Algebraic Equations

The solution of non-linear problems of theory of webs and shells by direct approximate methods leads to a system of non-linear algebraic equations, depending usually on a parameter. As usual, considerable difficulties are encountered in the solution of such systems. These difficulties mainly concern the initial approximation for iteration methods, the realization of the solution and also the identification of the obtained solution. Some methods of the solution to systems of non-linear algebraic equations are mentioned in the following text. It will be seen from the involved formulations that a general approach is in fact illusory. Every individual case needs to be studied separately, and then we can decide which method, or combination of methods, to apply.

Large Deflections of Elastic Isotropic Webs

The question of stability and behaviour of slender webs in the post-critical range is becoming important in connection with the production of high strength metal sheet and plates. This chapter presents a solution of the non-linear problem of the deformation of slender initially curved rectangular webs which are stiffened along their edges by elastically compressible stiffeners, flexible in the web plane. By introducing an initial deflection, we take account of certain (geometrical, structural and other) imperfections of “actual” (in comparison with ideally plane) webs.

Large Deflections of Orthotropic Webs

The problem of correct design of one-sidedly stiffened orthotropic plate elements of box-girder bridges attracted during the last years, and still attracts at the present time, plenty of attention; this being particularly due to the recent accidents on a number of large-span bridges, which highlighted the necessity to deal thoroughly with the afore-said problem.

Interaction of the Buckling of Thin-Walled Bars with the Buckling of Their Plate Elements

The design of the plate elements of compressed bars is based on the requirement that local buckling shall not occur before the bar as a whole has buckled while the effect of all initial imperfections is neglected.

Basic Assumptions of Theory of Slender Webs

Let us investigate a thin web of constant thickness, i.e. a rectangular prismatic body of which one dimension (thickness) is small in comparison with the other ones (width and depth) (Fig. 1.1). The plane which is parallel to the web surface and situated at the distance of t/2 from it will be termed middle plane. The line of intersection of the middle plane with the web edges is called boundary of the web. The middle plane is selected as plane xy.

Approximate Methods of Solution

Let us denote by R m a m-dimensional Euclid space. For every \( a = \{ {a_i}\} _{i = 1}^m,\;b = \{ {b_i}\} _{i = 1}^m \in {R^m} \) let us define