Lumped parameter model for the time-domain soil-structure interaction analysis of structures on pile foundations

A lumped parameter model for the time domain inertial soil-structure interaction analysis is proposed with reference to square pile group foundations. Simplified formulas are presented for estimating its parameters. The model is able to reproduce the coupled rotational-translational behaviour of the soil-foundation system. Formulas are calibrated from results of an extensive non-dimensional parametric analysis considering head-bearing pile groups. The closed-form expressions may be readily adopted to define the compliant base restraints of a generic structure for the non linear dynamic analysis carried out with commercial software

Finite elements for higher order steel–concrete composite beams

none4noThis paper presents finite elements for a higher order steel–concrete composite beam model developed for the analysis of bridge decks. The model accounts for the slab–girder partial interaction, the overall shear deformability, and the shear‐lag phenomenon in steel and concrete components. The theoretical derivation of the solving balance conditions, in both weak and strong form, is firstly addressed. Then, three different finite elements are proposed, which are characterised by (i) linear interpolating functions, (ii) Hermitian polynomial interpolating functions, and (iii) interpolating functions, respectively, derived from the analytical solution expressed by means of exponential matrices. The performance of the finite elements is analysed in terms of the solution con-vergence rate for realistic steel–concrete composite beams with different restraints and loading con-ditions. Finally, the efficiency of the beam model is shown by comparing the results obtained with the proposed finite elements and those achieved with a refined 3D shell finite element model.openGara F.; Carbonari S.; Leoni G.; Dezi L.Gara, F.; Carbonari, S.; Leoni, G.; Dezi, L

micropile foundation subjected to dynamic lateral loading

Abstract Thanks to their ease of installation, even in access-restricted spaces, micropiles are increasingly adopted for the seismic rehabilitation of existing structures. Moreover, both vertical and inclined micropiles are often used as foundation system for new constructions, ground improvements and many other applications. In order to deepen the knowledge of the dynamic behavior of those systems under horizontal loading, an extensive experimental study was carried out in an alluvial silty soil deposit on two single vertical micropiles and on a group of four inclined micropiles connected at the head by a concrete cap. Several testing procedures are exploited, in order to investigate the dynamic behavior of micropiles under different loading conditions and increasing force level, with special attention on the role of execution techniques and foundation configuration

Soil-structure interaction effects on the seismic response of multi-span viaducts

The paper focuses on the effects of soil-structure interaction in the seismic response of multi-span viaducts on pile foundations. Analyses are performed by means of the substructure approach: the soil-foundation systems are studied in the frequency domain to obtain the foundation input motion and the dynamic impedance functions; inertial interaction analyses are carried out in the time domain accounting for the material nonlinear behaviour. Suitable lumped parameter models are introduced to simulate the frequency dependent behaviour of the soilfoundation system. A specific procedure for selecting and scaling real ground motions is proposed and used for the definition of the spatial seismic input. The seismic response of bridges on compliant base is compared with that obtained from fixed base analyses discussing the significance of soil-structure interaction effects

Characterizing the Effect of Videophone Conversations on Intersection Driving Performance

The present study examined the efficacy of videophone conversations for enhancing conversation partner situational awareness and mitigating cell phone distraction during intersection drives. Younger and older drivers drove through simulated intersections in four conditions: undistracted, with an in-car passenger, with a remote partner who could see the driver and a subset of the driving scene via a videophone, and with a remote partner on a cell phone. Relative to the cell phone condition, passenger and videophone conversations enhanced situational awareness and mitigated distraction. Younger and older drivers showed similar benefits, although there were age-related costs to driving performance overall. Videophone information offers a simple and promising potential strategy to enhance partner situational awareness during cell phone conversations, even when the conversation partner can see only a subset of the driving scene

Training of YOLO Neural Network for the Detection of Fire Emergency Assets

Building assets surveys are cost and time demanding and the majority of current methods still rely on manual procedures. New technologies could be used to support this task. The exploitation of Artificial Intelligence (AI) for the automatic interpretation of data is spreading throughout various application fields. However, a challenge with AI is the very large number of training images required for robustly detect and classify each object class. This paper details the procedure and parameters used for the training of a custom YOLO neural network for the recognition of fire emergency assets. The minimum number of pictures for obtaining good recognition performances and the image augmentation process have been investigated. In the end, it was found that fire extinguishers and emergency signs are reasonably detected and their position inside the pictures accurately evaluated. The use case proposed in this paper for the use of custom YOLO is the retrieval of as-is information for existing buildings. The trained neural networks are part of a system that makes use of Augmented Reality devices for capturing pictures and for visualizing the results directly on site

Simultaneous effect of spatial variability of ground motion due to site conditions and SSI on the seismic response of multi-span viaducts

This work focuses on the effects of the spatial variability of the seismic motion due to site effects on the seismic response of multi-span viaducts on pile foundations. A methodology is proposed to include the effects of both soil-structure interaction and non-synchronous seismic actions in the nonlinear response of bridges. Then, some results of nonlinear dynamic analyses performed on a multi-span bridge founded on soft soil are presented. The deposit is characterized by an inclined layout of the bedrock and the seismic input is represented by a set of suitably selected real accelerograms. Comparisons with results obtained considering synchronous seismic motions demonstrate the influence of site effects on the response of long bridges

Seismic Response of Bridges Accounting for Soil-Structure Interaction effects and the Non-Synchronous Ground Motion due to 1D and 2D site analysis.

This work focuses on the effects of soil-structure interaction and the spatial variability of seismic motion due to site effects on the seismic response of a multi-span viaduct on pile foundations. In particular, site effects induced in a soft clay deposit by an inclined bedrock layout are evaluated through different models, characterised by an increasing level of accuracy, which allows determining the free-field motion that is adopted to perform soilstructure interaction analyses in the frame of the substructure approach. The seismic input is represented at the outcropping bedrock by a set of suitably selected and scaled real accelerograms. After a brief presentation of the adopted numerical procedure, analyses results are presented focusing on both site and structural response. Amplifications effects obtained from simplified linear equivalent 1D and nonlinear 2D site response models are compared, discussing the applicability of the simplified approach. Structural responses, obtained by considering the non-synchronous motion resulting from the local stratigraphic conditions, in conjunction with soil-structure interaction effects, are shown in terms of piers displacement and ductility demands. Furthermore, the role of soil structure interaction is clarified comparing results with those obtained from fixed base bridge models, proving that its contribution is more significant if the simplified model for site response is adopted