Hysteretic performance of a new blind bolted connection to concrete filled columns under cyclic loading: An experimental investigation

The structural performance and reliability of a new blind-bolting technique is investigated in this study. The new blind-bolt is termed Extended Hollobolt (EHB) and is a modification of the standard Hollobolt. The EHB enhances the tensile resistance and stiffness of the fastener by anchoring it in the concrete infill of a tubular column. This paper reports on an investigation into the cyclic behaviour of end-plate connections to concrete filled tubular (CFT) columns using the EHB. A series of six full-scale connections were tested under quasi-static cyclic loading. The key parameters investigated were amplitude of cyclic loading procedure, bolt grade, tube wall thickness, and concrete grade. The strength, stiffness, rotation capacity and energy dissipation capacity of the connections were evaluated at different load cycles. The EHB provided stable hysteretic behaviour with appropriate level of strength and stiffness, where strength is comparable to that of standard bolt-and-nut fasteners and where rigid behaviour can be achieved. The influence of tube wall thickness and concrete grade on the performance of the connection in terms of strength, stiffness, ductility and failure mode is investigated. It is shown that the required performance can be achieved by controlling the tube wall thickness and concrete strength. The results indicate that the connection can offer energy dissipation capacity and ductility appropriate for its potential use in seismic design. © 2012 Elsevier Ltd

Dynamic response of a laterally-loaded infinite rigid cylinder embedded in a saturated poroelastic medium

In this paper, an analytical solution for the response of a rigid cylinder embedded in a full-space poroelastic medium subjected to a dynamic lateral load is derived. The problem is idealised as a two-dimensional problem. The solution is obtained using Biot’s theory for acoustic waves. In this solution, the displacements of the solid skeleton and the pore pressure are expressed in terms of three scalar potentials. These potential correspond to the wave velocities of the slow and fast compressional wave and to the shear wave. The governing equation for the dynamic motion is expressed in the frequency domain using Fourier transformation and the potentials are shown to be given by Holmholtz equations

Building Information Modelling (BIM)—versioning for collaborative design

The engineering design process is a complicated activity. It is often characterized by multi-disciplinary teams in multiple places working together on a single project, using different models and software tools. In addition, such activities generate a large amount of data that require exchange among designers and stages of the work. In industry, the current collaboration approaches often focus on integrating and managing multiple models from multi-designers. Building Information Modelling (BIM) is playing a major role in facilitating collaboration. BIM provides an opportunity to electronically model and manage the vast amount of information embedded in a building project, from conception to completion. In the building design process, changes and modifications are inevitable even in the contemporary BIM approach. Such changes need to be well managed to keep track of changes to ensure that designers have an up-to-date version of the BIM model. The main goal of this research is to develop a collaborative BIM platform that tackles the challenges of integrating object versioning, as a change management approach, and an IFC model, as data representation of BIM. This has been done through suggesting new IFC extensions to add further concepts representing the history of changing to any object of the model. It also explores possibilities of adding or merging object-based change information to existing BIM models to enable the representation of design intentions, identification of affected changes numerically and visually. A prototype system is implemented in C#, using .NET framework and Revit API platform. This paper concludes that the proposed system can contribute to improving collaboration - in terms of tracking and management of affected changes during multi-disciplinary design process

Structural sustainability appraisal in BIM

The provision of Application Programming Interface (API) in BIM-enable tools can contribute to facilitating BIM-related research. APIs are useful links for running plug-ins and external programmes but they are yet to be fully exploited in expanding the BIM scope. The modelling of n-Dimensional (nD) building performance measures can potentially benefit from BIM extension through API implementations. Sustainability is one such measure associated with buildings. For the structural engineer, recent design criteria have put great emphasis on the sustainability credentials as part of the traditional criteria of structural integrity, constructability and cost. This paper examines the utilization of API in BIM extension and presents a demonstration of an API application to embed sustainability issues into the appraisal process of structural conceptual design options in BIM. It concludes that API implementations are useful in expanding the BIM scope. Also, the approach including process modelling, algorithms and object-based instantiations demonstrated in the API implementation can be applicable to other nD building performance measures as may be relevant to the various professional platforms in the construction domain

Experimental and numerical analysis of dynamic compressive response of Nomex honeycombs

Lightweight phenolic resin-impregnated aramid paper honeycombs, commercially known as Nomex®honeycombs, are promising cores for sandwich structures in aerospace applications due to their high ratios of stiffness and strength to density. The out-of-plane compressive properties of the Nomex honeycombs have been widely investigated under quasi-static and low strain rates (up to 300 s-1). There is a need to understand the behaviour of this structure under higher strain rate compression. This will widen the applicability of these structures to more areas such as debris impact and other impacts which induce high strain rates. This paper reports the out-of-plane compressive responses of Nomex honeycombs subject to quasi-static loading and high strain rate dynamic loading up to 1500 s-1. The work involves experimental measurements and numerical modelling and validation. The compressive responses of the honeycombs were measured using a sensitive magnesium alloy Kolsky bar setup with front and back face impacts. The failure modes of the Nomex honeycombs were identified to be different under quasi-static and dynamic compressions. Under quasi-static compression, the honeycombs failed with local phenolic resin fracture after the elastic buckling of the honeycomb walls. For the dynamic compression, the honeycombs failed with the stubbing of cell walls at the ends of specimens. A finite element (FE) numerical model was devised and validated with the experimental data. The FE model considered the strain rate effect of phenolic resin material. The model predictions were in good agreement with the experimental measurements and facilitated interpreting the out-of-plane compressive response of the Nomex honeycombs. It was shown that there was a linear compressive strength enhancement up to 30% from quasi-static to strain rate of 1500 s-1. The strength enhancement was governed by two mechanisms: the strain rate effect of the phenolic resin and inertial stabilization of the honeycomb unit cell walls, where 61%-74% of the enhancement was contributed by the inertial stabilization of the unit cell walls. In addition, it was shown that the impact method and initial imperfections had negligible effect on the compressive response of the Nomex honeycombs

Dynamic response of a laterally-loaded infinite rigid cylinder embedded in a saturated poroelastic medium

In this paper, an analytical solution for the response of a rigid cylinder embedded in a full-space poroelastic medium subjected to a dynamic lateral load is derived. The problem is idealised as a two-dimensional problem. The solution is obtained using Biot’s theory for acoustic waves. In this solution, the displacements of the solid skeleton and the pore pressure are expressed in terms of three scalar potentials. These potential correspond to the wave velocities of the slow and fast compressional wave and to the shear wave. The governing equation for the dynamic motion is expressed in the frequency domain using Fourier transformation and the potentials are shown to be given by Holmholtz equations