The rotational behaviour of clipped end plate connections

The rotational behaviour of clipped end plate connections was studied by subjecting nine clipped and three conventional or “unclipped” specimens with varying connection geometry to combined shear and moment and obtaining the corresponding moment–rotation characteristics. It was found that the clipped end plate connections in this investigation had more than adequate rotation capacity to permit an interior beam connected to a supporting member by this type of connection to achieve its full plastic moment, provided the length-to-depth ratio of the beam does not exceed 20. For the range of rotations that would be experienced by clipped end plate connections in a practical structure, a model originally developed to predict the moment–rotation behaviour of conventional shear end plate connections was modified so as to be applicable to clipped end plate connections. Good agreement was obtained between the test values and those predicted by the modified model. No adverse effect on the rotational behaviour of the connections was observed to result from the asymmetry caused by clipping the end plate. Key words: beams, bolts, columns, connections, fillet welds, limit states design, moment, rotation, shear tests, steel construction.

Staggered shear design of concrete beams: large-scale tests

Two large-scale reinforced concrete I-beams were tested to failure. The principal difference between the two specimens was the angle of inclination selected for the diagonal compression field in the web. A 45° inclination was used for specimen CM1 whereas a 31° inclination was used for specimen CM2. The validity of the truss model approach used in design was confirmed by the observed behaviour of the specimens.Diagonal crushing limits given in the Canadian code CAN3-A23.3-M84 were found to be conservative. It is recommended to use these limits for uniformly stressed web regions when applying the staggering concept of shear design. For nonuniformly stressed regions it is proposed to investigate potential failure mechanisms assuming an effective compressive strength of the web concrete of [Formula: see text].Canadian code rules for determining longitudinal bar cutoff locations may be unconservative. To prevent the formation of premature collapse crack mechanisms, it is recommended to extend the bars beyond the theoretical cutoff points by at least one-half of the stirrup spacing. Key words: beams, concrete, deflection, deformation, design, failure, girders, limit design method, reinforcement, shear strength, shear tests, strains, stresses, tests.

Design strengths of steel beam–columns

Some of the present Canadian rules for designing steel beam–columns can be improved if different formulations are used for designing against in-plane failure and out-of-plane buckling. An extension of the present use of nonlinear elastic analysis methods allows a common formulation for the in-plane strengths of braced and unbraced beam–columns, and generally leads to predictions that are more accurate than the present forms. Two alternative methods are developed for improving the design rules for estimating the out-of-plane strengths of beam–columns. The first of these retains the present familiar form, while the second uses a new form that will lead, in some cases, to significant economies. A method is also proposed for combining the separate formulations for the in-plane and out-of-plane strengths in order to estimate the biaxial bending resistances of beam–columns. Key words: beams, buckling, columns, flexure, steel, structural design, structural engineering, torsion.

Inelastic lateral buckling of steel beam–columns

A series of investigations of the inelastic lateral buckling behaviour of steel beam–columns is described. These originate from many previous studies of the elastic lateral buckling of beams. It was found that present methods of predicting the effects of moment gradient in elastic beam–columns are unnecessarily conservative, and it was concluded that many practical continuous beam–columns will have significant warping restraints.Fourteen inelastic lateral buckling tests were carried out on 9 continuous steel beam–columns. The results of these tests were compared with predictions made by a new and improved finite element computer method of analyzing inelastic buckling, and very good agreement was found. The analytical method was then used to develop a simple approximation for predicting the inelastic buckling of isolated beam–columns with unequal end moments, and a design method was proposed. Key words: beams, buckling, columns, flexure, residual stresses, steel, structural design, structural engineering, torsion.

Forces at flange–web connections in T-beams

The flanges of T- and I-beams are subjected, near their junctions with the web, to three in-plane forces: Nx, Ny, and Nxy, where x and y are horizontal axes parallel and normal to the beam axis. The finite element method is used to study the variation of these forces in T-beams under point or line load. It is concluded that forces Nx and Nxy can be determined for design purposes using conventional engineering beam theory. Force Ny, on the other hand, cannot be determined by available closed-form solutions. Based on a detailed parametric study, a simplified procedure is proposed for determining Ny. Key words: beams (supports), connections, finite element, flanges, loads (forces), T-beams, webs (supports).