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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Study on holding capacity of sandy-seabed anchors for marine aquaculture

Wu, Sheng-hai 03 July 2006 (has links)
In this study, the holding capacity of anchors and their design methodology are investigated. In general, three kinds of anchors have been used in cage aquaculture engineering, including embedment anchors, deadweight anchors, and pile anchors. The maximum holding capacity of embedment anchors was analyzed via the results of experiments by increasing the weight of anchors, while the best holding capacity of deadweight anchors was investigated by changing the types of shear keys. Moreover, the designs and considerations of pile anchors were also discussed in Appendix A. From the results of experiments, the maximum holding capacity of embedment anchors varies 12~19 times of their self-weight, and has the trend such as the holding capacity is in proportion to the weight of anchor. In the case of deadweight anchors, two methods were used to analyze the holding capacity, one is to consider the passive earth pressure behind each shear key of anchor block, and the other is to consider the net weight including the confined sand trapped inside of shear keys and its passive earth pressure at the outmost skirt key. It seems that the first method has more accurate than the second method until the number of keys equals 5 based on the experimental results. And, when the number of keys is greater and equal 6, the second method has better predictions than the first one. The main reason is that it is unable to fully develop the passive earth pressure in such a narrow space between the keys. Therefore, the interval between shear keys should at least equal 1 time of the key¡¦s penetration depth according to this study.
2

Fuzzy modeling of suction anchor behavior based on cyclic model tests data

Mucolli, Gent 06 May 2016 (has links)
This paper proposes a novel model that can predict the displacement of suction caisson anchors under monotonic and cyclic loading. Failure is assumed to occur when the accumulative monotonic and cyclic displacement along the load attachment point is over 60% of the diameter of the anchor. The anchors will go through lateral failure when the accumulative monotonic and cyclic displacement along the loading direction at the load attachment point is over 30% of the diameter. Hence, it is important to predict this displacement and therefore determine the expected failure of the anchor. However, it is difficult to predict displacement using the modern software without knowing the material properties of the soil and piles. Hence a new model that relies only on the normalized static load (Fa/Ff), normalized cyclic load (Fcy/Ff ), loading angle (Θ), and the number of cycles (N) is proposed. The inputs for training of the proposed model are (Fa/Ff), (Fcy/Ff), (Θ), (α) and (N). The output of the model will be the displacement normalized by the diameter of the anchor. To generalize the trained model, unused sets of data are used to validate the model. Furthermore, a comparative study is performed to evaluate the effectiveness of the proposed model. It is shown from extensive simulation that the model can accurately predict the normalized displacement of suction caisson anchors.
3

Fuzzy modeling of suction anchor behavior based on cyclic model tests data

Mucolli, Gent 06 May 2016 (has links)
This paper proposes a novel model that can predict the displacement of suction caisson anchors under monotonic and cyclic loading. Failure is assumed to occur when the accumulative monotonic and cyclic displacement along the load attachment point is over 60% of the diameter of the anchor. The anchors will go through lateral failure when the accumulative monotonic and cyclic displacement along the loading direction at the load attachment point is over 30% of the diameter. Hence, it is important to predict this displacement and therefore determine the expected failure of the anchor. However, it is difficult to predict displacement using the modern software without knowing the material properties of the soil and piles. Hence a new model that relies only on the normalized static load (Fa/Ff), normalized cyclic load (Fcy/Ff ), loading angle (Θ), and the number of cycles (N) is proposed. The inputs for training of the proposed model are (Fa/Ff), (Fcy/Ff), (Θ), (α) and (N). The output of the model will be the displacement normalized by the diameter of the anchor. To generalize the trained model, unused sets of data are used to validate the model. Furthermore, a comparative study is performed to evaluate the effectiveness of the proposed model. It is shown from extensive simulation that the model can accurately predict the normalized displacement of suction caisson anchors.
4

Tensile behavior of expansion and undercut anchors in concrete affected by alkali-silica reaction

Neuhausen, Alissa 30 September 2014 (has links)
This thesis addresses the tensile capacity and load-deflection behavior of wedge-type expansion and undercut anchors in concrete affected by alkali-silica reaction (ASR). ASR is a chemical reaction that occurs between alkalis in the cement and silica in the aggregates. The reaction occurs with the presence of moisture, forming a gel which expands and causes micro-cracking in the concrete. Researchers conducted 85 static unconfined tensile tests on control and ASR-affected specimens. The results indicate that anchors in concrete cracked due to ASR perform like anchors in concrete cracked due to other mechanisms. Up to a threshold value of the Comprehensive Crack Index (CCI) of at least 1.5 mm/m, all cracking, regardless of cause, has the same effect on the tensile breakout capacity of mechanical and undercut anchors. / text
5

Bonded Anchors in Concrete Under Sustained Loading

Droesch, Douglas 17 July 2015 (has links)
Post installed anchors come in either mechanical anchors that develop their strength purely through mechanical interlock with the base concrete, or bonded anchors that develop their strength by bonding anchor rod to the base concrete. Bonded anchors are either grouted, typically cementitious material, or adhesive, typically a chemical material. This thesis presents a current literature review of post-installed bonded anchors, preliminary testing of adhesive bonded anchors, and details of short term and long term test setups for future testing. The purpose of this thesis was to develop the test setups that will be used for future testing on anchors.
6

A theoretical and experimental investigation into statics and dynamics of chain cable lifters

Zandiyeh, A. R. K. January 1988 (has links)
No description available.
7

The analysis and design of inflatable hydraulic structures

Al-Shami, Alaa H. January 1982 (has links)
The range of possible uses of inflatable hydraulic structures is very great provided a suitable design and analysis technique is available. The object of this project was to study both theoretically and experimentally the behaviour and performance of inflatable hydraulic structures under both hydrostatic and hydrodynamic conditions for dams inflated with air, water and a combination of the two. The theoretical analysis was based on a finite element approach to design a dam under different inflation fluids in order to find the dam parameters of tension, profile of the dam, upstream slope, and elongation of the material under both hydrostatic and hydrodynamic conditions. A series of models of different sizes were constructed and tested under both hydrostatic and hydrodynamic conditions. A comparison of different output parameters was carried out between the experimental and theoretical results showing a good relationship between the two. Relationships were derived so that the length of the membrane could be found for the design of a dam to satisfy particular conditions. A new formula was derived for calculating the rate of flow and coefficient of discharge for all three types of inflation allowing the application of inflatable dam as a device for measuring discharge. A range of computer programs was written for the analysis and design of all dams based on the finite element approach. This work was restricted to single anchor dams with the anchor located on the upstream side.
8

Experimental in-plane behavior of a generic scale model drag embedment anchor in Kaolinite test beds

McCarthy, Katelyn Barbara 07 July 2011 (has links)
The trajectory and capacity are key components of the design of drag embedment anchor and drag-in vertically loaded anchors. This experimental testing program quantifies two factors that describe the anchor trajectory and capacity: the equilibrium bearing factor (Ne) and the tangential bearing factor (Ne). These factors can aid in the development of a numerical model of anchor behavior. A magnetometer device is used to track the orientation and location of the anchor during drag embedment. The results of the experimental testing program were compared with the results from a predictive model. The experimental program consisted of drag embedment tests with various testing conditions including different anchor line diameters and different initial pitch orientations. The results with the different anchor lines indicated that thinner anchor lines cause the anchor to dive deeper in the soil. The different initial pitch results indicate that regardless of the initial pitch of the anchor, the anchor rotates to a unique pitch trajectory within 2 fluke lengths. / text
9

Anchored Log Decks

Murison, Evangeline Rivera 10 April 2014 (has links)
To improve the performance of the conventional nail laminated bridge deck, three generations of innovative decks have been developed during the last three decades: (a) the stress laminated wood deck, (b) the stressed log bridge, and (c) the grout laminated wood deck. The grout laminated wood deck, the most recent wood deck, consists of trimmed logs interconnected with internal grout cylinders, in compression or tension. Previous research has shown that the grout cylinders have superior load distribution characteristics, but the cost of trimming the treated logs was found to be relatively high. Recently, research has been conducted to develop the next generation of the bridge wood decks, called the anchored log decks. The anchored log deck, meant for use as decking of steel girder bridges, consists of untrimmed discarded utility timber poles which have been treated with preservatives. The logs are held together by means of unstressed transverse proprietary Cintec anchors. The anchors consist of stainless steel rods encased in grout cylinders. Panels, each comprising of 5 to 6 logs, are preassembled to fit on a flatbed trailer for shipping. The smooth wearing surface over the log deck is provided by longitudinal sawn timber planks, with high-density foam filling the gap between the logs and the planks. The panels are inter-connected through inclined anchors passing through adjacent logs. At the University of Manitoba, an anchored log deck with five preassembled panels was constructed and tested to failure at several locations under both static and fatigue loads. The test results have shown that anchored log decks have the potential of being economical preassembled decks for steel girder bridges.
10

Structural and functional characterization of the inositol phospholipid of decay accelerating factor's glycolipid anchor

Walter, Elizabeth Ida January 1991 (has links)
No description available.

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