Variation of p-multipliers for pile groups in clayey soils

A common approach to assess the diverse response of the piles forming a pile group is the p-multipliers method. Although several studies have been occupied with the estimation of p-multipliers, usually assigned for pile group rows, they lead to values corresponding to specific soil conditions and pile group configuration. The aim of this study is to evaluate the variation of the aforementioned factors and for this purpose the results of a parametric three-dimensional nonlinear numerical analysis were used. The influence of the number of piles, the spacing, the soil shear strength and the deflection level on p-multiplier values is discussed and compared with values proposed by other researchers. © 2012 American Society of Civil Engineers

Design of reinforced embankments: Limit equilibrium and numerical methods

The aim of this paper is a comparative study of a reinforced embankment using two different design approaches. The first methodology is based on the limit equilibrium approach and the fundamental aspect of achieving equilibrium of forces and/or moments along predefined failure surfaces. The approach is widely used due to its simplicity and leads to an adequate and safe design, considered in many codes, by providing a global safety factor. However, it lacks the ability of predicting the kinematic field and the level of stresses, while a main shortcoming is the incapacity of materials to vary their ultimate strength in relation with the stress path. In the second approach, the powerful tool of numerical analysis is applied, providing the ability of modeling the mechanisms developed and allowing for shear strength variation with regard to stress and displacement field. In addition to estimating the safety factor, numerical analysis provides both displacement and stress field, indicating the areas where failure is to initiate and progress. Several numerical analyses under static and seismic loading have been carried out in order to assess the effect of both the multi-stage modeling and the creep action on the response of a reinforced embankment. Quantitative and qualitative comparison of the results arising from the aforementioned approaches is made and the main advantages and drawbacks are discussed

Analysis and design of reinforced embankments: Methodology, implementation and impact of critical parameters

This paper outlines the basic principles of analysis and design of reinforced embankments, according to the 'Design & Construction Guidelines' of the U.S. Department of Transportation, which are based on limit equilibrium principles. In addition, a case study of a high reinforced embankment with gabion's facing is presented, with reference to the parameters of design, the stages of analysis and design process, technical specifications and structural details of the project

Human action annotation, modeling and analysis based on implicit user interaction

This paper proposes an integrated framework for analyzing human actions in video streams. Despite most current approaches that are just based on automatic spatiotemporal analysis of sequences, the proposed method introduces the implicit user-in-the-loop concept for dynamically mining semantics and annotating video streams. This work sets a new and ambitious goal: to recognize, model and properly use "average user's" selections, preferences and perception, for dynamically extracting content semantics. The proposed approach is expected to add significant value to hundreds of billions of non-annotated or inadequately annotated video streams existing in the Web, file servers, databases etc. Furthermore expert annotators can gain important knowledge relevant to user preferences, selections, styles of searching and perceptio

The role of site effects on elevated seismic demands and corollary structural damage during the October 30, 2020, M7.0 Samos Island (Aegean Sea) Earthquake

On October 30, 2020 14:51 (UTC), a moment magnitude (M) 7.0 (USGS, EMSC) earthquake occurred in the Aegean Sea. This paper presents the reconnaissance findings regarding the site effects on recorded strong ground motion intensities and duration, along with the resulting induced-structural damage in Izmir Bay and Samos Island, respectively. In all rock records, relatively high intensity long period rock spectral accelerations were observed in the mid to long period range of 0.5–1.5 s, which are attributed to the source, more specifically, to the slower rupture-mechanism of the event. These rich spectral intensities were further amplified by soil site effects and soil-superstructure resonance, leading to two to six times amplified overall responses and prolonged seismic shaking durations, more pronounced in Bayrakli and other Izmir Bay sites in Turkey. However, these amplified and prolonged excitations are still below design basis earthquake levels, which addresses the lack of proper structural design and construction deficiencies, as the underlying causes for the collapse to heavy damage performance of 795 buildings. On the other hand, although located only about 10 km from the rupture (22 km from the epicenter) and within the near fault zone, the town of Vathy on Samos Island (Greece) was rather lightly affected by the earthquake, with relatively few collapsed or heavily damaged buildings, partially attributed to the low height/low weight of structures in the area. However, a concentration of damage in low-rise buildings in Ano Vathy hill is considered indicative of a combination of coupled valley and topography effects on the strong motion. This event once again addressed the need to develop region-specific zonation and provisions, when more general code practices are proven to be inadequate to assess these extreme site effects