Robust Geotechnical Design – A New Design Perspective

In routine geotechnical engineering practice, the engineer has to work with a small sample of data due to budget constraint. Because of complexity of soil deposits, it is often difficult to determine correctly the statistics of soil parameters that are required for reliability-based design of foundations. Furthermore, the traditional reliability-based design is sensitive to the variation of noise factors such as uncertain soil parameters. To address this dilemma, the authors present a new design methodology, termed robust geotechnical design. This new design methodology aims to make the response of a geotechnical system immune to, or robust against, the variation of noise factors by carefully adjusting the design parameters. This methodology is realized through a multi-objective optimization, in which all the design requirements such as safety, robustness, and cost are explicitly considered. The results of such optimization are often expressed as a Pareto Front, which defines a trade-off relationship between cost and robustness, whereas safety is guaranteed. This enables the engineer to make an informed design decision according to a target cost or robustness. The significance of new design methodology is illustrated with an example of shallow foundation design

Engaging Health Care Employers to Develop an AS in Health Sciences Degree With Stackable Credentials

Many pre-clinical nursing students at Bronx Community College (BCC) of the City University of New York fail to sustain momentum, resulting in derailed or prolonged paths to graduation. To help increase students’ chances of graduating, and finding careers within the health professions, BCC is developing a new Associate of Science (AS) in Health Sciences with embedded “stackable” certifications. This paper will describe how faculty hosted a round table discussion with employers to obtain information regarding growing health sectors and needed skills, the salient themes that arose from the event, and how these findings are being used to create the degree’s curriculum

Calibration under uncertainty for finite element models of masonry monuments

Historical unreinforced masonry buildings often include features such as load bearing unreinforced masonry vaults and their supporting framework of piers, fill, buttresses, and walls. The masonry vaults of such buildings are among the most vulnerable structural components and certainly among the most challenging to analyze. The versatility of finite element (FE) analyses in incorporating various constitutive laws, as well as practically all geometric configurations, has resulted in the widespread use of the FE method for the analysis of complex unreinforced masonry structures over the last three decades. However, an FE model is only as accurate as its input parameters, and there are two fundamental challenges while defining FE model input parameters: (1) material properties and (2) support conditions. The difficulties in defining these two aspects of the FE model arise from the lack of knowledge in the common engineering understanding of masonry behavior. As a result, engineers are unable to define these FE model input parameters with certainty, and, inevitably, uncertainties are introduced to the FE model

Towards the Validation of Dynamical Models in Regions where there is no Data

The creation of computer models is often driven by the need to make predictions in regions where there is no data (i.e. extrapolations). This makes validation challenging as it is difficult to ensure that a model will be suitable when it is applied in a region where there are no observations of the system of interest. The current paper proposes a method that can reveal flaws in a model which may be difficult to identify using traditional approaches for model calibration and validation. The method specifically targets the situation where one is attempting to model a dynamical system that is believed to possess time-invariant calibration parameters. The proposed approach allows these parameters to vary with time, even though it is believed that they are time-invariant. The of such an analysis is to identify key discrepancies - indications that a model has inherent flaws and, as a result, should not be used to influence decisions in regions where there is no data. The proposed method isn't necessarily a predictor of extrapolation performance, rather, it is a stringent test that, the authors believe, should be applied before extrapolation is attempted. The approach could therefore form a useful part of wider validation frameworks in the future.</jats:p

Experimental investigation of a full-scale timbrel masonry cross vault subjected to vertical settlement

La versión de editor/PDF no puede utilizarse. Debe enlazar a la versión de editor con DOI. Author's post-print must be released with a Creative Commons Attribution Non-Commercial No Derivatives License[EN] Masonry cross vaults are among the most attractive structures ever created by the human race. Although cross vaults have been the subject of various numerical and experimental studies, they are still in need of further investigation. In the research described here, carried out at the ICITECH laboratories of the Universitat Politecnica de Valencia (Spain), a full-scale timbrel cross vault was constructed and tested under the vertical settlement of one of its supports. The geometry and construction technique of the vault resembled those in a church on the outskirts of Valencia, one of which had collapsed due to a soil settlement. The timbrel vault's behaviour was monitored by 23 sensors placed on its inner and outer surfaces and subsequently analysed from the results obtained in the tests. As expected, the vault experienced a fairly ductile response during the test, while peculiar crack patterns were observed in the form of bending cracks in the lateral arches, which were mostly found to follow the mortar joints in the upper surface of one of the diagonal elliptic arches.The authors wish to express their gratitude to the Spanish Ministry of Economy, Industry and Competitiveness for the funding provided through Project BIA 2014-59036-R, and also to LIC-Levantina Ingenieria y Constructiin and Grupo Puma for their invaluable assistance.Torres Górriz, B.; Bertolesi, E.; Moragues, JJ.; Calderón García, PA.; Adam, JM. (2019). Experimental investigation of a full-scale timbrel masonry cross vault subjected to vertical settlement. Construction and Building Materials. 221:421-432. https://doi.org/10.1016/j.conbuildmat.2019.06.015S42143222