Numerical investigation of the resistance of precast RC pinned beam-to-column connections under shear loading

In precast technology, the effective design and construction is related to the behaviour of the connections between the structural members in order to cater for all service, environmental and earthquake load conditions. Therefore, the design and detailing of the connections should be undertaken consistently and with awareness of the desired structural response. In the research presented herein an analytical expression is proposed for the prediction of the resistance of precast pinned connections under shear monotonic and cyclic loading. The proposed formula addresses the case where the failure of the connection occurs with simultaneous flexural failure of the dowel and compression failure of the concrete around the dowel, expected to occur either when (a) adequate concrete cover of the dowels is provided (d > 6 D) or (b) adequate confining reinforcement (as defined in the article) is foreseen around the dowels in the case of small concrete covers (d < 6 D). The expression is calibrated against available experimental data and numerical results derived from a nonlinear numerical investigation. Emphasis is given to identifying the effect of several parameters on the horizontal shear resistance of the connection such as: the number and diameter of the dowels; the strength of materials (concrete, grout, steel); the concrete cover of the dowels; the thickness of the elastomeric pad; the type of shear loading (monotonic or cyclic); the pre-existing axial stress in the dowels; and the rotation of the joint. In addition, recommendations for the design of precast pinned beam-to-column connections are given, especially when the connections are utilised in earthquake resistant structures

On the dynamics of rocking motion of single rigid–block structures

This paper describes the behavior of single rigid-block structures under dynamic loading. A comprehensive experimental investigation has been carried out to study the rocking response of four blue granite stones with different geometrical characteristics under free vibration, and harmonic and random motions of the base. In total, 275 tests on a shaking table were carried out in order to address the issues of repeatability of the results and stability of the rocking motion response. Two different tools for the numerical simulations of the rocking motion of rigid blocks are considered. The first tool is analytical and overcomes the usual limitations of the traditional piecewise equations of motion through a Lagrangian formalism. The second tool is based on the discrete element method (DEM), especially effective for the numerical modeling of rigid blocks. A new methodology is proposed for finding the parameters of the DEM by using the parameters of the classical theory. An extensive comparison between numerical and experimental data has been carried out to validate and define the limitations of the analytical tools under study.Ecoleader Group 4Fundação para a Ciência e a Tecnologia (FCT) -: SFRH/BPD/17449/2004, SFRH/BD/9014/200

Numerical model for the non-linear dynamic analysis of multi-storey structures with semi-rigid joints with specific reference to the Algerian code

The current paper aims at investigating the dynamic response of rigid and semi-rigid connections of steel structures built in high seismic areas. A nonlinear dynamic analysis model, which is an extension to the simplified and direct mechanical model used in the static analysis, is proposed and discussed. The novelty of the model consists in the introduction of a bar element with semi-rigid joint as a single element without the need to discretise it (i.e. without a finite element mesh) in the program where non-linearity is considered in the flexibility factor of the stiffness matrix. The model developed is validated through application to examples of steel frames with different types of connections under dynamic forces. The results obtained were very satisfactory. This work is motivated by the need for the revision of the Algerian seismic code (RPA99v2003) which does not yet consider provisions for the design of structures with semi-rigid joints. Based on the results of the study carried out on a multi-storey structure with different types of joints subjected to seismic loading, it can be seen that the safety justifications recommended by Algerian regulations RPA99 in terms of relative displacements as well as the dimension of the seismic joint prove to be too conservative compared to those by Eurocode 8