Engineering Commons^™

Reliability Analysis Of Shallow Foundations Bearing Capacity On Sand, Ali Alhajami

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Bearing capacity of shallow foundation is one of the most challenging problems for engineers. The difficulty comes from multiple sources of variability and uncertainty. There is an uncertainty in live load. Soil properties including: unit weight, cohesion, and angle of friction represent sources of variability in the determining bearing capacity. The current theories used in practice only estimate bearing capacity and does not give an exact value for it because of these sources of variability. Currently, there are Terzaghi, Meyerhof, Vesic, and Hansen theories for dealing with this problem. Based on previous research Terzaghi theory was found to be the …

Active Tuned Mass Damper Control Of Wind Turbine Nacelle/Tower Vibrations With Damaged Foundations, Breiffni Fitzgerald

Breiffni Fitzgerald

The aim of this paper is to develop an active structural control scheme to control wind turbine nacelle/tower out-of-plane vibration. An active tuned mass damper (ATMD) is designed an placed inside the turbine nacelle. An EulerLagrangian wind turbine model based on energy formulation is developed for this purpose, which considers the structural dynamics of the system and the interaction between in-plane and out-of-plane vibrations. Also, the interaction between the blades and the tower including the ATMD is considered. The wind turbine is subjected to gravity and turbulent aerodynamic loadings. A three-dimensional (3D) model of a wind turbine foundation is designed …

Analyses Of Reinforced Embankment On Soft And Hard Foundations, Sowarapan Duangkhae, Dennes Bergado, Pankaj Baral, Barry T. Ocay

Faculty of Engineering and Information Sciences - Papers: Part A

In this paper, the analyses and design using conservative limit equilibrium methods (AASHTO simplified and FHWA structure stiffness methods) were compared with the working stress methods called K-stiffness method (original and modified K-stiffness methods). Moreover, the predictions from the K-stiffness methods were confirmed from the observed data for a reinforced embankment on a hard foundation. Furthermore, since the reinforcement loads increased due to post-construction settlements for reinforced embankments on soft foundation, a further modification of the K-stiffness method is proposed. This further modification is concerned with the proposed settlement factor. The validity of this further modification is demonstrated by the …

The Behaviour Of Connections In Segmental Precast Concrete Pile Systems, Evan Causer

Theses

Driven precast concrete segmental piles are a popular foundation solution. Segmental pile systems incorporate connections into the pile, therefore it is important to be confident that the strength of the pile joints is comparable to that of the pile cross-section.

The primary objective of the research was to examine the behaviour of connections in segmental precast concrete pile systems. This was achieved by undertaking a literature review, laboratory testing and Finite Element Analysis (FEA).

The uses of segmental concrete pile systems are described and a review of the available pile joints is given. A review of the relevant design codes …

Winkler Model For Dynamic Response Of Composite Caisson-Piles Foundations: Lateral Response, Rui Zhong, Maosong Huang

Faculty of Engineering and Information Sciences - Papers: Part A

As the first part of a sequence focusing on the dynamic response of composite caisson-piles foundations (CCPFs1), this paper develops a simplified method for the lateral response of these foundations. A Winkler model for the lateral vibration of the CCPF is created by joining the two components, the caisson and the pile group, where the four-spring Winkler model is utilized for the caisson and axial-lateral coupled vibration equations are derived for the pile group. For determining the coefficients of the four-spring Winkler model for the caissons, embedded footing impedance is used and a modification on the rotational embedment factor is …

Simplified Analytical Method For Seismic Response Of Composite Caisson-Piles Foundations, Rui Zhong, Maosong Huang

Faculty of Engineering and Information Sciences - Papers: Part A

Seismic response of a new type of foundation，the composite caisson-piles foundation，is studied through a simplified analytical method. The focus is the contribution of the piles beneath the caisson in increasing the earthquake resistance of the foundation-superstructure system. Firstly，considering the interaction between the soil and foundation with dynamic Winkler model，the equation of kinematic response of the composite foundation under S-wave is derived. Secondly，a simplified model for the seismic response of the foundation-column-lumped mass system in frequency domain is built；and with Fourier transformation this method is applied to transient seismic problems. Thirdly，with an example of soil-foundation-superstructure seismic behavior，this proposed method is validated …