Universal Critical Sections

2021 ◽  
pp. 159-174
Author(s):  
Christian Maurer
Keyword(s):  
Critical Sections

CRITICAL SECTIONS FOR FLEXURE IN PRESTRESSED GIRDERS WITH INCLINED TOP FLANGES

PCI Journal ◽  
1971 ◽  
Vol 16 (6) ◽  
pp. 59-69
Author(s):  
M. A. Saeedҟ ◽  
J. B. Kennedy
Keyword(s):  
Prestressed Girders ◽  
Critical Sections

The Effect of Cutoffs on the Uplift Pressure Beneath the Hydraulic Structures Floor

2018 ◽  
Vol 6 (3) ◽  
pp. 20-28
Author(s):  
Faisal Al Tabatabaie ◽  
Dhabia Sabeeh Al Waily
Keyword(s):  
Potential Energy ◽  
Hydraulic Structure ◽  
Hydraulic Structures ◽  
Outer Face ◽  
Analogue Model ◽  
Electrical Analogue ◽  
Uplift Pressure ◽  
Different Depths ◽  
The Stability ◽  
Critical Sections

The use of cutoffs underneath the hydraulic structures is considered a safe solution to ensure the stability of hydraulic structure against uplift pressure and piping phenomenon in addition to the sliding and overturning forces of the water. These cutoffs are used at critical sections underneath the floor of hydraulic structure to substitute with their depths the horizontal lengths of the creep line of the hydraulic structure base. In this paper, the experimental method- by using electrical analogue model- was carried out to plot the flow net and study the efficiency of the front and rear faces of the cutoffs for dissipating the potential energy of the percolating water underneath the floor of hydraulic structure. An electrical analogue model which was used in this study consists of twenty five models with different depths of upstream and downstream cutoffs. After plotting the flow net for all models, it is concluded that the efficiency of the inner sides are less than that of the outer sides which were investigated before in this topic of this work that both faces reduction values in the uplift pressure are considered the same, where the efficiency of the outer face of upstream cutoff is (70.35) % and for the inner face is (29.64)%, while for the downstream cutoff the efficiency for the outer face is (76.21)% and for the inner face is (23.79)% .

scholarly journals Ranking the critical sections of railway networks

2020 ◽  
pp. 095440972092568
Author(s):  
Ratthaphong Meesit ◽  
John Andrews
Keyword(s):  
Network Flow ◽  
Topological Analysis ◽  
Preventive Strategy ◽  
Railway Network ◽  
Macroscopic Models ◽  
Railway Systems ◽  
Railway Networks ◽  
Network Simulation Model ◽  
The Impact ◽  
Critical Sections

Railway systems are now facing an increasing number of threats such as aging infrastructures and climate changes. The identification of critical network sections provides infrastructure managers with the ability to understand the impact of a disruption and creates a suitable preventive strategy to counter such threats. To this end, various vulnerability analysis methods have been proposed for railway networks. Two main types of methods, network topological analysis and network flow-based analysis, have been developed. Both approaches are constructed based on macroscopic models, which take only some railway properties such as network structure, train and passenger flow into account. Thus, the results obtained are high level approximations. This study proposes a new analysis method, which is developed based on the stochastic-microscopic railway network simulation model. The method can be applied to identify the critical sections of a railway network. The effect of impact levels and occurrence times of a disruption on the network section criticality is presented. An application of the proposed model is demonstrated using the Liverpool railway network in the UK.

Failure mode investigation and re-design of heavy-duty commercial vehicle bogie bracket

2019 ◽  
Vol 43 (3) ◽  
pp. 405-415
Author(s):  
P. Thangapazham ◽  
L.A. Kumaraswamidhas ◽  
D. Muruganandam
Keyword(s):  
Maximum Stress ◽  
Suspension System ◽  
Heavy Duty ◽  
Commercial Vehicles ◽  
Road Load ◽  
Road Surfaces ◽  
Strain Data ◽  
Critical Sections ◽  
Bracket Base ◽  
Base Design

Heavy-duty commercial vehicles play a significant role in commodity logistics. For each of these vehicles, the suspension is the most essential system to support the load and road shock. Bogie type suspension system is employed to safeguard the vehicle from road shock. The bogie bracket is a juncture between the chassis and the axle in the suspension system. The bogie bracket has been identified as a critical part of the suspension system. In the present study, bogie bracket base design and modelling was performed using computer-aided engineering (CAE). The strength of the bogie was tested to identify weaker sections. Design modifications were performed to improve the strength on identified critical sections through reinforcement techniques. A road load data acquisition (RLDA) test was conducted under different road conditions to validate CAE results. Five different rough-road road surfaces were chosen for RLDA testing. Using strain gauges, strain data were acquired during the test. Corresponding stress values were obtained and maximum stress was found in all driving conditions. For the base design bogie bracket, under RLDA test, crack initiation and crack propagation were identified under vertical loads. A reinforced bogie bracket was designed and found to have a higher strength and longer expected life than that of the base design.

On the Age of Certain Species of Trigonia from the Jurassic Rocks of Kachh (Cutch)

1935 ◽  
Vol 72 (4) ◽  
pp. 184-189 ◽  
Author(s):  
L. F. Spath
Keyword(s):  
General Interest ◽  
Jurassic Rocks ◽  
The Subject ◽  
Critical Sections ◽  
Geological Magazine

One of the problems left unsolved in my “Revision of the Jurassic Cephalopod Fauna of Kachh” consisted of the determination of the exact age of certain Jurassic beds that had yielded (in addition to ammonites) species of Trigonia. Among these, T. smeei J. de C. Sowerby is of unusual, general interest; and, as readers of the Geological Magazine may remember, this species has been the subject of much controversy. It was one of the species whose “morphological position, viewed from the evolutionary standpoint”, caused them to be described as Cretaceous. Thanks to the continued researches of Mr. J. H. Smith, of Bhuj, who has been good enough to send me new collections from various critical sections in Kachh, I am now in a position to add to the evidence for a Jurassic age of a number of these species of Trigonia. If it be asked why, in a work on cephalopods, I have gone out of my way to express scepticism regarding the use of species of Trigonia for correlation, I can only say that this genus happened to be represented among the ammonite material sent to me. There is no reason, so far as I can see, why Trigonia should not be quite as useful for zonal purposes as ammonites. I have been equally sceptical about Stolley’s work on belemnites. But in either case I will leave the results to speak for themselves. It seems to me that if Upper Oxfordian species like Trigonia smeei and such allies as T. tenuis, T. tra-peziformis, T. remota Kitchin, not to mention the associated Astarte, Gervillia, Cucullaea, Exogyra, etc., could be claimed to be of Cretaceous age by one of the most eminent authorities, then it is time to remind the general palaeontologist again of what workers on ammonites have realized long ago.

Critical Section Selection Methodology for the U.S. EPR™ Standard Nuclear Power Plant

2010 ◽  
Author(s):  
Se-Kwon Jung ◽  
Adam Goodman ◽  
Joe Harrold ◽  
Nawar Alchaar
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Structural Design ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Safety Evaluation ◽  
Critical Section ◽  
Selection Methodology ◽  
Critical Sections ◽  
The U.S

This paper presents a three-tier, critical section selection methodology that is used to identify critical sections for the U.S. EPR™ Standard Nuclear Power Plant (NPP). The critical section selection methodology includes three complementary approaches: qualitative, quantitative, and supplementary. These three approaches are applied to Seismic Category I structures in a complementary fashion to identify the most critical portions of the building whose structural integrity needs to be maintained for postulated design basis events and conditions. Once the design of critical sections for a particular Seismic Category I structure is complete, the design for that structure is essentially complete for safety evaluation purposes. Critical sections, taken as a whole, are analytically representative of an “essentially complete” U.S. EPR™ design; their structural design adequacy provides reasonable assurance of overall U.S. EPR™ structural design adequacy.

Stress-deformation predictions for the LG 4 main dam

1984 ◽  
Vol 21 (2) ◽  
pp. 213-222 ◽  
Author(s):  
J. J. Paré ◽  
N. S. Verma ◽  
H. M. S. Keira ◽  
A. D. McConnell
Keyword(s):  
Hydraulic Fracturing ◽  
Material Properties ◽  
Laboratory Testing ◽  
Deformation Behaviour ◽  
Earth Dam ◽  
Interesting Aspect ◽  
James Bay ◽  
Hydroelectric Development ◽  
Stress Deformation ◽  
Critical Sections

The LG 4 dam, the second largest structure on the La Grande Complex of the James Bay hydroelectric development, is 125 m high, about 4 km long, and is composed of 19 × 106 m3 of fill materials.The design of the dam is characterised by (i) a zoned earth–rockfill section based on a judicious use of the limited quantities of various materials available, (ii) a 70 m high abutment in the river valley with a steep inclination of about 55°, and (iii) a 50 m high section of the dam with its axis curved in the downstream direction.Detailed stress-deformation analyses were carried out in the critical sections of the dam using finite element methods to verify any presence of arching and hydraulic fracturing potentials in the nonplastic till core. An interesting aspect of these analyses was the fact that the material properties were established based on laboratory testing as well as the observed deformation behaviour of the already completed 156 m high LG 2 main dam.The analyses have indicated that the design has adequate reserve of safety against hydraulic fracturing and arching. Nevertheless, the design sections and material placement requirements were optimised, where necessary, to ensure a satisfactory behaviour of the dam. The instrumentation design was also adapted to the findings of this study. Keywords: earth dam, steep abutment, stress-strain, hydraulic fracturing, arching.

Comparison of flow behaviour in pressurized gating systems using water models and numerical simulation

2016 ◽  
Vol 14 (3) ◽  
pp. 652-674
Author(s):  
V. Jaiganesh ◽  
K. Prakasan
Keyword(s):  
Flow Visualization ◽  
Flow Behaviour ◽  
Water Model ◽  
Gating System ◽  
Commercial Software ◽  
Content Type ◽  
Filling Pattern ◽  
Flow Through ◽  
Water Models ◽  
Critical Sections

Purpose The purpose of this work is to visualize the flow behaviour in critical sections of a pressurized gating system. Design/methodology/approach The investigation was carried out using water models of gating system that were designed, invoking the principles of similitude. Water was used as the filling medium, and the manner of flow through various sections of the gating system and the cavity was recorded with a high-speed camera capable of capturing images up to 10,000 frames per second. This was followed by an analysis of the results obtained from each phase. Finally, computer simulations of flow were carried out using commercial software. The manner of filling as observed during experiments and that during simulation were compared so as to draw some useful conclusions on the utility of flow visualization using water models and the capability of software to predict the filling pattern during casting process. It was understood that water models are powerful aids for understanding the intricacies of flow through critical sections of the gating systems. Findings It was observed that water models are a reliable indicator of the mould-filling process. Further, substantial differences in the filling pattern were observed between water model experiments and filling simulation using commercial software. Research limitations/implications The findings are limited to horizontal plate-type castings. Also, the influence of surface roughness in the flow through the runner is not considered. Originality/value This work facilitates understanding of the importance of flow visualization on the quality and reliability of castings.

Dynamic analysis of two dimensional simply supported orthotropic bridge decks

1978 ◽  
Vol 5 (1) ◽  
pp. 58-69 ◽  
Author(s):  
G. G. Kulkarni ◽  
S. F. Ng
Keyword(s):  
Theoretical Analysis ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Bridge Decks ◽  
Two Dimensional ◽  
Amplification Factors ◽  
Simply Supported ◽  
Forced Vibration Analysis ◽  
Critical Sections

Forced vibration analysis of two dimensional bridge deck structures involves complex mathematical procedures and therefore analysis is often based on beam idealization of equivalent plates. This simplification yields close agreement only for long span bridges where plate action is relatively insignificant. However, such a concept of beam idealization cannot be successfully utilized in the case of short span bridges where plate action is predominant and where the determination of the distribution of dynamic deflections and amplification factors at critical sections of such plates is of prime concern. The principal objective of the present investigation is the forced vibration analysis of longitudinally stiffened, simply supported orthotropic bridge decks utilizing a new concept of interconnected beam idealization. The theoretical analysis deals with determination of amplification factors and dynamic deflections along critical sections of the plate treated as a series of interconnected beams. The aspect ratios of the plates under investigation as series of interconnected beams are designed to cover a wide range of plate to beam transition. The theoretical analysis is supplemented by an extensive experimental programme.In conclusion, it is seen that this concept of interconnected beam idealization not only takes into account the plate action of the deck structure but also reduces greatly the complexity of mathematical formulation. A good comparison between the theoretical and the experimental results indicates that this concept can be used to advantage for analysis and, within certain limitations, for design purposes.

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