T.Q. Li

Behaviour of flush end-plate composite connections with unbalanced moment and variable shear/moment ratios—I. Experimental behaviour

Abstract A series of seven end-plate beam-to-column connection tests is reported; these include one pure steel connection and six composite connections. The main variables investigated are the degrees of unbalanced moment and the shear/moment ratio. Comprehensive instrumentation has been used to monitor: beam strains, column strains, rebar strains and bolt forces as well as member and connection deformations. This comprehensive monitoring permits a full understanding of the behaviour of this kind of connection. In addition, the large number of recorded variables provides data for the detailed validation of numerical analysis methods.

Required rotations and moment redistribution for composite frames and continuous beams

Abstract Using the theoretical method previously developed to determine the required rotations in the support regions of composite frames, several sets of numerical results have been obtained for variations in the key parameters known to influence behaviour. Using these numerical results, correlation analyses were conducted to determine the most influential factors governing the required rotations. By utilising the governing factors and regression analysis, empirical equations were obtained to directly link the rotation requirements to the degree of moment redistribution necessary to develop the full strength of composite beams. Based on these equations, some numerical results are presented which define achievable rotation requirements and thus of the degree of moment redistribution.

Determination of rotation capacity requirements for steel and composite beams

Abstract A method is presented for the calculation of the necessary joint rotations to permit the use of moment redistribution as the basis for the design of semi-continuous steel and composite frames. The method is based on the use of moment-curvature relationships obtained from consideration of the basic steel and concrete stress-strain curves. It simplifies the determination of the support rotations required for specific percentage redistributions of support moments to the mid-span cross-section as used in EC4 by considering these to be composed of an elastic and a plastic part. Several different load cases are considered, together with a wide range of beam properties. The resulting calculation method, which uses only formulae and graphs, is illustrated by an example.

Connection element method for the analysis of semi-rigid frames

Abstract A general procedure for incorporating the effects of joint flexibility into standard methods for the analysis of frames is presented. The method can allow for joint flexibility associated with all six degrees of freedom normally considered when analysing three-dimensional frames, including coupling between deformations. It can also allow for the finite size and exact location of connections. Simple examples using the moment distribution technique, slope deflection equations and matrix stiffness method illustrate the application of the proposal. Additional examples to illustrate the effects of connection length on the frame moment distribution, lateral drift and column load capacities are also present.

The experimental behaviour of a full-scale, semi-rigidly connected composite frame: Overall considerations

Abstract The testing of a two-span, one-bay, two-storey, full-scale, composite frame is described. Details are presented of the test arrangements, instrumentation used to provide detailed test histories and the observed modes of failure. A full examination of the results, including comparisons with predicted behaviour and implications for the design of composite frames is provided in a companion paper.

Behaviour of flush end-plate composite connections with unbalanced moment and variable shear/moment ratios—II. Prediction of moment capacity

Abstract Based on experimental data and the EC3 method for bare steel connections, a comprehensive method has been developed for predicting the moment capacities of flush end-plate composite connections. In this method the effects of both non-symmetrical moments and varying shear/moment ratios are taken into account. Since the determination of the internal forces for the steel components follows the EC3 specification, this method is consistent with EC3. If the reinforcement ratio is set as zero, then the moment capacity of bare steel connections can also be predicted by using this method. The design equations are presented in a style that facilitates the necessary calculations.

The experimental behaviour of a full-scale, semi-rigidly connected composite frame: Detailed appraisal

Abstract A detailed appraisal of the results obtained from testing the pair of composite frames described in the companion paper (Li et al., Journal of Constructional Steel Research, 1996, 39, 167–191) is presented. The overall response of the frames is considered in terms of the internal force distribution, whilst the behaviour of the connections and the beams is also considered separately. Comparisons have been made between the test results and predictions for connection rotations, beam curvatures, deflections and moment capacities. Particular attention is given to beam deflections at serviceability load levels. For design at the ultimate limit state the quasi-plastic approach is recommended.

Modelling composite connection response

Publisher Summary This chapter discusses a finite element model to simulate the structural behavior of composite flush endplate beam to column connections. This model has been validated against test results and compared with a simplified calculation method; both checks demonstrate its accuracy. Parametric studies using the model to investigate variations in: reinforcement ratio, degree of shear connection and shear-span/moment ratio are also described. For successful numerical modeling of any composite connection the following items must be properly represented: reinforcement, shear studs (considering slip between the slab and the beam, and also the percentage of shear interaction provided), steel beam and column (including buckling and plasticity), bolts (including slip), separation and closure at the interface of the endplate and the column flange and load introduction.

Design of composite finplate and angle cleated connections

Abstract A design method for composite finplate and angle cleated connections is described. The method covers both symmetric and non-symmetric connections and allows for the presence of axial compression in the column. It is similar to that developed by the authors for flush endplate connections. Verification against all available test results demonstrates the methods ability to accurately predict the moment capacity of finplate and angle cleated connections. A worked example for the angle cleated connection is used to illustrate the methods application.