Author: Sivapalan GajanPublisher:
ISBN:
Category :
Languages : en
Pages : 348
Book Description
Physical and Numerical Modeling of Nonlinear Cyclic Load-deformation Behavior of Shallow Foundations Supporting Rocking Shear Walls
Author: Sivapalan GajanPhysical and Numerical Modeling of Nonlinear Cyclic Load-deformation Behavior of Shallow Foundations Supporting Rocking Shear Walls
Author: Sivapalan GajanProceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering
Author: The Organizing Committee of the 16th ICSMGEPublisher: IOS Press
ISBN: 1614996563
Category : Technology & Engineering
Languages : en
Pages : 3742
Book Description
The 16th ICSMGE responds to the needs of the engineering and construction community, promoting dialog and exchange between academia and practice in various aspects of soil mechanics and geotechnical engineering. This is reflected in the central theme of the conference 'Geotechnology in Harmony with the Global Environment'. The proceedings of the conference are of great interest for geo-engineers and researchers in soil mechanics and geotechnical engineering. Volume 1 contains 5 plenary session lectures, the Terzaghi Oration, Heritage Lecture, and 3 papers presented in the major project session. Volumes 2, 3, and 4 contain papers with the following topics: Soil mechanics in general; Infrastructure and mobility; Environmental issues of geotechnical engineering; Enhancing natural disaster reduction systems; Professional practice and education. Volume 5 contains the report of practitioner/academic forum, 20 general reports, a summary of the sessions and workshops held during the conference.
Examination of the Past, Present and Future of the Physical and Numerical Modeling of Lateral Loading of Shallow Foundations
Author: Jeremy M. ThomasRocking Response of Bridges on Shallow Foundations
Author: Jose Antonio UgaldeWorkshop on Modeling of Nonlinear Cyclic Load-Deformation Behavior of Shallow Foundations
Author: Nonlinear Rotational Behaviour of Shallow Foundations on Cohesive Soil
Author: Thomas Brian AlgiePublisher:
ISBN:
Category : Foundations
Languages : en
Pages : 348
Book Description
The most recent version of the New Zealand design and loadings standard eliminated a clause for the design of rocking foundations. This thesis addresses that clause by presenting a strong argument for rocking shallow foundations in earthquake resistant design. The goals of the research were to perform large scale field experiments on rocking foundations, develop numerical models validated from those experiments, and produce a design guide for rocking shallow foundations on cohesive soil. Ultimately, this thesis investigates the nonlinear rotational behaviour of shallow foundations on cohesive soil. Field experiments were performed on an Auckland residual soil, predominantly clay. The experiment structure - a large scale steel frame - was excited first by an eccentric mass shaker and second by a quick release (snap-back) method. The results show that rocking foundations produce highly nonlinear moment-rotation behaviour and a well defined moment capacity. A hyperbolic equation is proposed in Chapter 4 utilising the initial stiffness and moment capacity to predict nonlinear pushover response. The results show that the initial stiffness should be based on an 'operational soil modulus' rather than a small strain soil modulus. Therefore, the reduction factor from the small strain modulus was around 0.6 for the experiment testing. Additionally, the experiments showed that rocking foundations demonstrate significant damping; snap-back experiments revealed an average damping ratio of around 30%. Experiment data validated two numerical models developed for this study: one, a finite element model in Abaqus and the other, a spring bed model in OpenSEES. The models showed that both forms of nonlinearity in rotating shallow foundations - geometric nonlinearity and material nonlinearity - should be considered in shallow foundation analysis. These models also confirmed the need for an 'operational soil modulus' on shallow foundation rocking, and analysis of varying vertical loads suggested that this reduction factor is dependent on the vertical factor of safety of the foundation. Lastly, two design methods are presented, a displacement-based method and a forcebased method, and two examples of rocking shear walls are given. The displacementbased method is the recommended option, and it is shown that design displacements and rotations compare well to time history analyses performed using the validated OpenSEES model.
Numerical Modeling of the Nonlinear Cyclic Response of Shallow Foundations
Author: Chad William HardenPublisher:
ISBN:
Category : Buildings
Languages : en
Pages : 494
Book Description
Numerical Modeling of the Nonlinear Cyclic Response of Shallow Foundations
Author: Chad William HardenPublisher:
ISBN:
Category : Buildings
Languages : en
Pages : 494
Book Description
Centrifuge Modeling, Numerical Analyses, and Displacement-based Design of Rocking Foundations
Author: Lijun DengPublisher:
ISBN: 9781267398345
Category :
Languages : en
Pages :
Book Description
This dissertation investigated the use of rocking shallow foundations in improving the seismic performance of ordinary bridges. Centrifuge model tests and numerical analyses were conducted and displacement-based design guidelines for rocking foundations were proposed. Three series of centrifuge model tests of lumped-mass models and bridge system models were completed. Slow cyclic loading tests and dynamic shaking tests were performed. It was observed that rocking bridges were more stable than conventional hinging-column bridges. Rocking foundations had the re-centering ability that resulted in less residual rotations and showed non-degrading moment capacity. Rocking foundations were a good energy dissipater. The rocking-induced settlement increased with the cumulative footing rotation and decreased with the factor of safety for vertical bearing capacity. Concrete pads beneath rocking foundations were effective in reducing the rocking-induced settlement. A beam-on-nonlinear-Winkler-foundation finite element model was developed in OpenSees to study the collapse potential of bridges with rocking foundations or hinging columns. Parametric studies including large deformation effects compared the performance and stability of stiff, flexible, tall and short rocking-foundation and hinging-column systems. The rocking and hinging systems had similar pushover curves for fair comparison. A suite of pulse-like and broadband motions were used as the input motions and incremental dynamic analysis was performed. The results showed that, in a probabilistic sense, bridges with rocking foundations were more stable than bridges with hinging columns if their fundamental periods were the same and if base shear coefficients to initiate hinging or rocking mechanisms were the same. Maximum drifts were not significantly affected by changing between rocking and hinging mechanisms except near collapse, but residual drifts are smaller for rocking systems. The results also challenged the notion that rocking systems require a different design approach than hinging column systems. Direct displacement-based design (DDBD) guidelines were proposed for the design of rocking shallow foundations. A multi-linear hysteretic model for rocking foundations was proposed based on prior experimental studies and was decomposed into an elastic element and a plastic element to account for the radiation and soil hysteretic energy dissipation during foundation rocking. An ordinary bridge composed of a column and a nonlinear rocking foundation was integrated into a single visco-elastic element and then the displacement-based design was applied. Step-by-step design procedure was developed and elaborated with a design example in detail. The design example showed the feasibility of the proposed guidelines.