No description available.

A problem endemic in the development of the built environment is poor communication between structural and geotechnical specialists. Through better communication and considering the structure and foundation as an integrated system, new opportunities may arise for achieving superior performance. This thesis investigates the seismic performance of the integrated system through the development of integrated structure-foundation models using the Ruaumoko structural analysis program. A detailed representation of the structural and foundation systems was created using Ruaumoko, providing insight into the response of a range of integrated structure-foundation systems during seismic loading. In developing both shallow and deep foundation models, some modifications were made to Ruaumoko elements in order to improve the foundation model, but generally existing element configurations were used to represent foundations. Multiple structural and foundation designs were developed using a range of approaches. Use of a range of shallow foundation design methods identified the significant impact that moment loading had on foundation performance. Partial uplift of footings was identified as detrimental to footing performance as it shifted the rotational axes, increasing moment loads and reducing effective footing area. Pinned connections between the structure and shallow footings eliminated these effects at the expense of significant redistribution of actions in the structure and increased displacements. Variation of soil conditions showed that softer soil was most likely to reduce demands on the structure at the expense of foundation non-linearity. Reduced stiffness and increased radiation damping characteristics of raft foundations compared to footing foundation systems reduced the demands on three storey structures for all soil conditions. Increased structural demands were identified for the ten storey structure as a result of the reduced impact of foundation characteristics on the response of the integrated system. The level of rotational restraint at the head of pile foundations had a considerable effect on the structure and the foundation, with free-head piles developing the largest pile displacements and actions. Reduced rotational stiffness caused a substantial change in the distribution of structural actions, while increasing rotational restraint moved the characteristics closer to the response of fixed base models. Softer soil conditions greatly increased non-linearity in the foundation soil without any definitive improvement in structural performance.

A parametric analysis of typical base isolated bridges was conducted. The bridges were located in different soil types and were subjected to three different earthquakes (recorded on soft and medium soils). The work had two main objectives: to asses the effects of the nonlinear behavior of the isolation pads of the bridges on the seismic responses (accelerations, displacements, and pier seismic forces), and to study combined effects of base isolation and inertial interaction due to the presence of flexible foundations. The analytical models used for the study were selected on the basis of initial evaluation of different models proposed in the literature to represent a bridge structure and to evaluate the isolation pads’ nonlinear behavior. The bridges studied were developed with a three-dimensional model. After completing the studies, 2 degree of freedom models were used to investigate more general trends of the inertial SSI effects for the base isolated bridges. The results of the work show the efficiency of base isolation pads in improving the seismic performance of bridges in most cases. They suggest that the inertial SSI effects will not be generally important for bridge foundations designed with a factor of safety of 3, with more than one line of piles in either direction since they will be very stiff foundations. But they also showed that for slender piers it is important to carefully evaluate the translations on top of the piers due to the rocking effects of the foundation.

A continuous formulation to calculate the dynamic stiffness matrix of structural members with distributed masses is presented in detail and verified with some simple examples. The dynamic model of a specific bridge (the Marga-Marga bridge in Chile) was developed using this formulation, and the model was then used to obtain the transfer functions of the motions at different points of the bridge due to seismic excitation. The model included rubber pads, used for base isolation, as additional members. The transfer functions were obtained with and without rubber pads to investigate their effect. The dynamic stiffness of complete pile foundations was calculated by a semi-analytical solution with Poulos?? assumption. General observations on group effects under various conditions were obtained from the result of these studies. The dynamic stiffness of the pile foundations for the Marga-Marga bridge was then obtained and used to study the soil structure interaction effects on the seismic response of the bridge. Records obtained during a real earthquake were examined and interpreted in light of the results from all these analyses. Finally, conclusions and recommendations on future studies are presented.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 218-220). Available also in a digital version from Dissertation Abstracts.

No description available.

A problem endemic in the development of the built environment is poor communication between structural and geotechnical specialists. Through better communication and considering the structure and foundation as an integrated system, new opportunities may arise for achieving superior performance. This thesis investigates the seismic performance of the integrated system through the development of integrated structure-foundation models using the Ruaumoko structural analysis program. A detailed representation of the structural and foundation systems was created using Ruaumoko, providing insight into the response of a range of integrated structure-foundation systems during seismic loading. In developing both shallow and deep foundation models, some modifications were made to Ruaumoko elements in order to improve the foundation model, but generally existing element configurations were used to represent foundations. Multiple structural and foundation designs were developed using a range of approaches. Use of a range of shallow foundation design methods identified the significant impact that moment loading had on foundation performance. Partial uplift of footings was identified as detrimental to footing performance as it shifted the rotational axes, increasing moment loads and reducing effective footing area. Pinned connections between the structure and shallow footings eliminated these effects at the expense of significant redistribution of actions in the structure and increased displacements. Variation of soil conditions showed that softer soil was most likely to reduce demands on the structure at the expense of foundation non-linearity. Reduced stiffness and increased radiation damping characteristics of raft foundations compared to footing foundation systems reduced the demands on three storey structures for all soil conditions. Increased structural demands were identified for the ten storey structure as a result of the reduced impact of foundation characteristics on the response of the integrated system. The level of rotational restraint at the head of pile foundations had a considerable effect on the structure and the foundation, with free-head piles developing the largest pile displacements and actions. Reduced rotational stiffness caused a substantial change in the distribution of structural actions, while increasing rotational restraint moved the characteristics closer to the response of fixed base models. Softer soil conditions greatly increased non-linearity in the foundation soil without any definitive improvement in structural performance.

A problem endemic in the development of the built environment is poor communication between structural and geotechnical specialists. Through better communication and considering the structure and foundation as an integrated system, new opportunities may arise for achieving superior performance. This thesis investigates the seismic performance of the integrated system through the development of integrated structure-foundation models using the Ruaumoko structural analysis program. A detailed representation of the structural and foundation systems was created using Ruaumoko, providing insight into the response of a range of integrated structure-foundation systems during seismic loading. In developing both shallow and deep foundation models, some modifications were made to Ruaumoko elements in order to improve the foundation model, but generally existing element configurations were used to represent foundations. Multiple structural and foundation designs were developed using a range of approaches. Use of a range of shallow foundation design methods identified the significant impact that moment loading had on foundation performance. Partial uplift of footings was identified as detrimental to footing performance as it shifted the rotational axes, increasing moment loads and reducing effective footing area. Pinned connections between the structure and shallow footings eliminated these effects at the expense of significant redistribution of actions in the structure and increased displacements. Variation of soil conditions showed that softer soil was most likely to reduce demands on the structure at the expense of foundation non-linearity. Reduced stiffness and increased radiation damping characteristics of raft foundations compared to footing foundation systems reduced the demands on three storey structures for all soil conditions. Increased structural demands were identified for the ten storey structure as a result of the reduced impact of foundation characteristics on the response of the integrated system. The level of rotational restraint at the head of pile foundations had a considerable effect on the structure and the foundation, with free-head piles developing the largest pile displacements and actions. Reduced rotational stiffness caused a substantial change in the distribution of structural actions, while increasing rotational restraint moved the characteristics closer to the response of fixed base models. Softer soil conditions greatly increased non-linearity in the foundation soil without any definitive improvement in structural performance.

A problem endemic in the development of the built environment is poor communication between structural and geotechnical specialists. Through better communication and considering the structure and foundation as an integrated system, new opportunities may arise for achieving superior performance. This thesis investigates the seismic performance of the integrated system through the development of integrated structure-foundation models using the Ruaumoko structural analysis program. A detailed representation of the structural and foundation systems was created using Ruaumoko, providing insight into the response of a range of integrated structure-foundation systems during seismic loading. In developing both shallow and deep foundation models, some modifications were made to Ruaumoko elements in order to improve the foundation model, but generally existing element configurations were used to represent foundations. Multiple structural and foundation designs were developed using a range of approaches. Use of a range of shallow foundation design methods identified the significant impact that moment loading had on foundation performance. Partial uplift of footings was identified as detrimental to footing performance as it shifted the rotational axes, increasing moment loads and reducing effective footing area. Pinned connections between the structure and shallow footings eliminated these effects at the expense of significant redistribution of actions in the structure and increased displacements. Variation of soil conditions showed that softer soil was most likely to reduce demands on the structure at the expense of foundation non-linearity. Reduced stiffness and increased radiation damping characteristics of raft foundations compared to footing foundation systems reduced the demands on three storey structures for all soil conditions. Increased structural demands were identified for the ten storey structure as a result of the reduced impact of foundation characteristics on the response of the integrated system. The level of rotational restraint at the head of pile foundations had a considerable effect on the structure and the foundation, with free-head piles developing the largest pile displacements and actions. Reduced rotational stiffness caused a substantial change in the distribution of structural actions, while increasing rotational restraint moved the characteristics closer to the response of fixed base models. Softer soil conditions greatly increased non-linearity in the foundation soil without any definitive improvement in structural performance.

Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 156-164)