Staggered shear design of concrete beams: large-scale tests

1987 ◽  
Vol 14 (2) ◽  
pp. 257-268 ◽  
Author(s):  
Lou M. Cerruti ◽  
Peter Marti
Keyword(s):  
Large Scale ◽  
Design Method ◽  
Shear Design ◽  
Diagonal Compression ◽  
Observed Behaviour ◽  
Potential Failure ◽  
Large Scale Tests ◽  
Compression Field ◽  
The Web ◽  
Key Words Beams

Two large-scale reinforced concrete I-beams were tested to failure. The principal difference between the two specimens was the angle of inclination selected for the diagonal compression field in the web. A 45° inclination was used for specimen CM1 whereas a 31° inclination was used for specimen CM2. The validity of the truss model approach used in design was confirmed by the observed behaviour of the specimens.Diagonal crushing limits given in the Canadian code CAN3-A23.3-M84 were found to be conservative. It is recommended to use these limits for uniformly stressed web regions when applying the staggering concept of shear design. For nonuniformly stressed regions it is proposed to investigate potential failure mechanisms assuming an effective compressive strength of the web concrete of [Formula: see text].Canadian code rules for determining longitudinal bar cutoff locations may be unconservative. To prevent the formation of premature collapse crack mechanisms, it is recommended to extend the bars beyond the theoretical cutoff points by at least one-half of the stirrup spacing. Key words: beams, concrete, deflection, deformation, design, failure, girders, limit design method, reinforcement, shear strength, shear tests, strains, stresses, tests.

Background to the general method of shear design in the 1994 CSA-A23.3 standard

1999 ◽  
Vol 26 (6) ◽  
pp. 827-839 ◽  
Author(s):  
Khaldoun N Rahal ◽  
Michael P Collins
Keyword(s):  
Prestressed Concrete ◽  
Structural Design ◽  
Design Method ◽  
Bending Moment ◽  
Shear Capacity ◽  
Shear Design ◽  
Standard Design ◽  
Modified Compression Field Theory ◽  
Compression Field ◽  
General Method

The 1994 CSA-A23.3 standard "Design of concrete structures" includes a new shear design method based on the equations of the modified compression field theory (MCFT). This "general method" is a simplification which casts the MCFT in the traditional "Vc + Vs" format resulting in a set of six general equations and two tables. This new method unifies the treatment of reinforced, partially prestressed and fully prestressed concrete and accounts, in a rational manner, for the effects of axial load and bending moment on shear capacity. Simplifying the MCFT while maintaining acceptable generality and accuracy involved a number of considerations and assumptions. This paper gives the background to the development of these shear design equations and tables of the general method.Key words: beams, building codes, crack width and spacing, diagonal cracking, reinforced concrete, shear strength, size effect in shear, structural design.

Optimization of Piece-Wise Conical Nozzles: Theory and Application

2018 ◽  
Author(s):  
Karsten Hasselmann ◽  
Muhammad Aiman Bin Khamalrudin ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig
Keyword(s):  
Flow Separation ◽  
Large Scale ◽  
Design Method ◽  
Elevated Pressure ◽  
Conical Nozzle ◽  
Measured Velocity ◽  
Pressure Distributions ◽  
Optimization Study ◽  
Large Scale Tests ◽  
Separation Number

In this contribution, an optimization study based on computational fluid dynamics (CFD) in combination with Stratford’s analytical separation criterion was developed for the design of piece-wise conical contraction zones. The occurrence of flow separation can be formally described by a newly introduced dimensionless separation number. In the optimization process, the risk of flow separation is reduced by minimizing this separation number. It was found that the optimized piece-wise conical nozzle shape did not correspond to a simple geometric approximation of the ideal polynomial shape. In fact, it was beneficial to reduce the deflection in the outlet region for a piece-wise conical nozzle stronger than for a conventional one. In order to validate the new design method, large-scale tests for different nozzle designs were conducted. The measured velocity profiles and wall pressure distributions agreed well with the CFD predictions. The new method was applied for designing the contraction zone of a new closed-loop organic vapor wind tunnel (CLOWT) working at elevated pressure levels.

Scalable Authoritative OWL Reasoning for the Web*

2011 ◽  
pp. 131-177 ◽  
Author(s):  
Aidan Hogan ◽  
Andreas Harth ◽  
Axel Polleres
Keyword(s):  
Real World ◽  
Large Scale ◽  
Scale Up ◽  
Original Publication ◽  
Web Data ◽  
Rule Based ◽  
Recent Developments ◽  
Observed Behaviour ◽  
Extended Discussion ◽  
The Web

In this chapter, the authors discuss the challenges of performing reasoning on large scale RDF datasets from the Web. Using ter-Horst’s pD* fragment of OWL as a base, the authors compose a rule-based framework for application to Web data: they argue their decisions using observations of undesirable examples taken directly from the Web. The authors further temper their OWL fragment through consideration of “authoritative sources” which counter-acts an observed behaviour which they term “ontology hijacking”: new ontologies published on the Web re-defining the semantics of existing entities resident in other ontologies. They then present their system for performing rule-based forward-chaining reasoning which they call SAOR: Scalable Authoritative OWL Reasoner. Based upon observed characteristics of Web data and reasoning in general, they design their system to scale: the system is based upon a separation of terminological data from assertional data and comprises of a lightweight in-memory index, on-disk sorts and file-scans. The authors evaluate their methods on a dataset in the order of a hundred million statements collected from real-world Web sources and present scale-up experiments on a dataset in the order of a billion statements collected from the Web. In this republished version, the authors also present extended discussion reflecting upon recent developments in the area of scalable RDFS/OWL reasoning, some of which has drawn inspiration from the original publication (Hogan, et al., 2009).

Mapping global water projects: improving access to donor investment information on the web

Water Policy ◽  
2003 ◽  
Vol 5 (3) ◽  
pp. 203-212
Author(s):  
J. Lisa Jorgensona
Keyword(s):  
Water Resources ◽  
Web Sites ◽  
Large Scale ◽  
Technical Assistance ◽  
Water Withdrawal ◽  
Small Scale ◽  
Water Projects ◽  
Essential Information ◽  
Water Project ◽  
The Web

This paper discusses a series of discusses how web sites now report international water project information, and maps the combined donor investment in more than 6000 water projects, active since 1995. The maps show donor investment:  • has addressed water scarcity,  • has improved access to improvised water resources,  • correlates with growth in GDP,  • appears to show a correlation with growth in net private capital flow,  • does NOT appear to correlate with growth in GNI. Evaluation indicates problems in the combined water project portfolios for major donor organizations: •difficulties in grouping projects over differing Sector classifications, food security, or agriculture/irrigation is the most difficult.  • inability to map donor projects at the country or river basin level because 60% of the donor projects include no location data (town, province, watershed) in the title or abstracts available on the web sites.  • no means to identify donor projects with utilization of water resources from training or technical assistance.  • no information of the source of water (river, aquifer, rainwater catchment).  • an identifiable quantity of water (withdrawal amounts, or increased water efficiency) is not provided.  • differentiation between large scale verses small scale projects. Recommendation: Major donors need to look at how the web harvests and combines their information, and look at ways to agree on a standard template for project titles to include more essential information. The Japanese (JICA) and the Asian Development Bank provide good models.

scholarly journals Design of a Variable-Stiffness Compliant Skin for a Morphing Leading Edge

2021 ◽  
Vol 11 (7) ◽  
pp. 3165
Author(s):  
Zhigang Wang ◽  
Yu Yang
Keyword(s):  
Composite Laminate ◽  
Large Scale ◽  
Design Method ◽  
Leading Edge ◽  
Variable Stiffness ◽  
Manufacturing Constraints ◽  
Aircraft Wing ◽  
Noise Abatement ◽  
Civil Aircraft ◽  
Final Profile

A seamless and smooth morphing leading edge has remarkable potential for noise abatement and drag reduction of civil aircraft. Variable-stiffness compliant skin based on tailored composite laminate is a concept with great potential for morphing leading edge, but the currently proposed methods have difficulty in taking the manufacturing constraints or layup sequence into account during the optimization process. This paper proposes an innovative two-step design method for a variable-stiffness compliant skin of a morphing leading edge, which includes layup optimization and layup adjustment. The combination of these two steps can not only improve the deformation accuracy of the final profile of the compliant skin but also easily and effectively determine the layup sequence of the composite layup. With the design framework, an optimization model is created for a variable-stiffness compliant skin, and an adjustment method for its layups is presented. Finally, the deformed profiles between the directly optimized layups and the adjusted ones are compared to verify its morphing ability and accuracy. The final results demonstrate that the obtained deforming ability and accuracy are suitable for a large-scale aircraft wing.

scholarly journals Optimal Design of Novel Blade Profile for Savonius Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3484
Author(s):  
Tai-Lin Chang ◽  
Shun-Feng Tsai ◽  
Chun-Lung Chen
Keyword(s):  
Wind Energy ◽  
Drag Force ◽  
Wind Turbines ◽  
Rural Areas ◽  
Large Scale ◽  
Design Method ◽  
Angular Position ◽  
Vertical Axis ◽  
Blade Profile ◽  
Main Concept

Since the affirming of global warming, most wind energy projects have focused on the large-scale Horizontal Axis Wind Turbines (HAWTs). In recent years, the fast-growing wind energy sector and the demand for smarter grids have led to the use of Vertical Axis Wind Turbines (VAWTs) for decentralized energy generation systems, both in urban and remote rural areas. The goals of this study are to improve the Savonius-type VAWT’s efficiency and oscillation. The main concept is to redesign a Novel Blade profile using the Taguchi Robust Design Method and the ANSYS-Fluent simulation package. The convex contour of the blade faces against the wind, creating sufficient lift force and minimizing drag force; the concave contour faces up to the wind, improving or maintaining the drag force. The result is that the Novel Blade improves blade performance by 65% over the Savonius type at the best angular position. In addition, it decreases the oscillation and noise accordingly. This study achieved its two goals.

scholarly journals Evaluation of dietary intake assessed by the Dutch self-administered web-based dietary 24-h recall tool (Compl-eat™) against interviewer-administered telephone-based 24-h recalls

2017 ◽  
Vol 6 ◽  
Author(s):  
Saskia Meijboom ◽  
Martinette T. van Houts-Streppel ◽  
Corine Perenboom ◽  
Els Siebelink ◽  
Anne M. van de Wiel ◽  
...  
Keyword(s):  
Dietary Intake ◽  
Large Scale ◽  
Alcohol Intake ◽  
Lower Number ◽  
Vitamin B ◽  
Food Groups ◽  
Web Based ◽  
The Web

AbstractSelf-administered web-based 24-h dietary recalls (24 hR) may save a lot of time and money as compared with interviewer-administered telephone-based 24 hR interviews and may therefore be useful in large-scale studies. Within the Nutrition Questionnaires plus (NQplus) study, the web-based 24 hR tool Compl-eat™ was developed to assess Dutch participants’ dietary intake. The aim of the present study was to evaluate the performance of this tool against the interviewer-administered telephone-based 24 hR method. A subgroup of participants of the NQplus study (20–70 years, n 514) completed three self-administered web-based 24 hR and three telephone 24 hR interviews administered by a dietitian over a 1-year period. Compl-eat™ as well as the dietitians guided the participants to report all foods consumed the previous day. Compl-eat™ on average underestimated the intake of energy by 8 %, of macronutrients by 10 % and of micronutrients by 13 % as compared with telephone recalls. The agreement between both methods, estimated using Lin's concordance coefficients (LCC), ranged from 0·15 for vitamin B1 to 0·70 for alcohol intake (mean LCC 0·38). The lower estimations by Compl-eat™ can be explained by a lower number of total reported foods and lower estimated intakes of the food groups, fats, oils and savoury sauces, sugar and confectionery, dairy and cheese. The performance of the tool may be improved by, for example, adding an option to automatically select frequently used foods and including more recall cues. We conclude that Compl-eat™ may be a useful tool in large-scale Dutch studies after suggested improvements have been implemented and evaluated.

Structural topology optimization of bridge girders in cable supported bridges

2018 ◽  
Author(s):  
Mads Baandrup ◽  
Ole Sigmund ◽  
Niels Aage
Keyword(s):  
Topology Optimization ◽  
Large Scale ◽  
Design Method ◽  
Optimization Method ◽  
Bridge Girders ◽  
Structural Topology ◽  
Box Girders ◽  
Box Girder ◽  
Fine Mesh ◽  
Further Development

<p>This work applies a ultra large scale topology optimization method to study the optimal structure of bridge girders in cable supported bridges.</p><p>The current classic orthotropic box girder designs are limited in further development and optimiza­ tion, and suffer from substantial fatigue issues. A great disadvantage of the orthotropic girder is the loads being carried one direction at a time, thus creating stress hot spots and fatigue problems. Hence, a new design concept has the potential to solve many of the limitations in the current state­ of-the-art.</p><p>We present a design method based on ultra large scale topology optimization. The highly detailed structures and fine mesh-discretization permitted by ultra large scale topology optimization reveal new design features and previously unseen eff ects. The results demonstrate the potential of gener­ ating completely different design solutions for bridge girders in cable supported bridges, which dif­ fer significantly from the classic orthotropic box girders.</p><p>The overall goal of the presented work is to identify new and innovative, but at the same time con­ structible and economically reasonable, solutions tobe implemented into the design of future cable supported bridges.</p>

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