Academic literature on the topic 'Buttress'
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Journal articles on the topic "Buttress"
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Memmott, Jane, and Stephen L. Sutton. "Sandfly stratification on tree buttresses in a Costa Rican tropical rainforest." Journal of Tropical Ecology 10, no. 1 (February 1994): 87–101. http://dx.doi.org/10.1017/s0266467400007732.
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ABSTRACTIn humid forests tree buttresses and tree trunks are used as diurnal resting sites by phlebotomine sandflies (Diptera: Psychodidae). When several species are present on the same buttress, the sandfly species are spatially segregated resulting in a pattern of vertical stratification on the buttress within 100 cm of ground level. A change in the distribution of one species induces a change in the distribution of an adjacent species. This is demonstrated under both natural and experimental conditions. Observations of sandflies at dawn and dusk have revealed that the buttress is used as a swarming site; this behaviour provides our favoured explanation for the patterns of vertical stratification on tree buttresses.
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CHAPMAN, COLIN A., LES KAUFMAN, and LAUREN J. CHAPMAN. "Buttress formation and directional stress experienced during critical phases of tree development." Journal of Tropical Ecology 14, no. 3 (May 1998): 341–49. http://dx.doi.org/10.1017/s0266467498000261.
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Patterns of buttress formation in tropical trees vary greatly within and among species. In Kibale National Park, Uganda, some form of a buttres was found on 23% of the 78 species (1785 trees) sampled from a variety of distantly related families. Large differences in buttress formation were documented within a single family and even within the same genus. Previous studies have suggested that buttresses are mechanical adaptations to counter asymmetric loads experienced during brief critical phases in a tree’s development and these persist after the need for a mechanical support has disappeared. As a tree grows from the understorey, up to the canopy, or emerges from the canopy, the potential number of occasions that a tree will experience directional stress increases. Many canopy level trees will probably have been in the vicinity of a treefall gap during their development, while emergent trees may experience gap exposure in addition to wind stresses associated with canopy emergence. Therefore, it is predicted that understorey trees should have fewer and less developed buttresses (after correcting for overall tree size) than canopy trees, which should have fewer and less developed buttresses than emergent trees. Detailed measurements of buttresses from 194 trees of eight species support this prediction. There was no evidence that trees thought to have experienced directional stress associated with selective logging almost 30 y ago had increased the number or size of existing buttresses. The pattern of buttressing in Kibale generally supports the idea that buttresses are mechanical adaptations to counter episodic asymmetric loads, and that buttresses persist after the need for a mechanical support has disappeared.
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WANG, YU-TZU, PO-FANG WANG, CHIEN-TZUNG CHEN, CHIH-HAO CHEN, and CHUN-LI LIN. "BIOMECHANICAL ANALYSIS TO VERIFY THE BUTTRESS THEORY WHEN USING THE ANATOMICAL THIN TITANIUM MESH PLATE FOR ZYGOMATICOMAXILLARY COMPLEX BONE FRACTURE." Journal of Mechanics in Medicine and Biology 19, no. 02 (March 2019): 1940025. http://dx.doi.org/10.1142/s0219519419400256.
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Objective: The aim of this study was to investigate the biomechanics of the facial skeletal for understanding the buttress after fixation with standard and modified anatomical thin titanium mesh (ATTM) plates by finite element (FE) analysis. Methods: Standard ATTM (SATTM) plate designed as the “L”-shape anticipated to be fixed in the ZMC anterior maxilla and lateral buttress to increase the fixation screw anchoring strength and another modified ATTM (MATTM) plate with a protrusion in the medial side and a slot and barb design in the lateral side to enhance the zygomaticomaxillary/nasomaxillary buttresses and provide precise positioning to the ZMC segments were studied by the FE analysis under masticatory forces with 250[Formula: see text]N. Result: The FE simulation results indicated that the total displacement distribution of the maxillary for ZMC fracture fixation with MATTM plate was smaller than that of SATTM plate. Stress concentration was found at the frontal and alveolar processes of the maxillary bone for SATTM plate fixation. Local vector plots of the first principal stress near the frontal process of the maxillary and zygomaticofacial formen of the zygomatic indicated that the stress flow for MATTM plate fixation was relatively close to nasomaxillary buttress, and the zygomaticomaxillary buttress, respectively. Conclusions: This study concluded that “L”-shape ATTM plate designed with a protrusion in the medial side and a slot and barb design in the lateral side can enhance the zygomaticomaxillary/nasomaxillary buttresses under uniform occlusal condition.
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Ukleja, Janusz. "Application of Spatial Supporting Construction as an Effective Method for Stabilising a Landslide." Geosciences 10, no. 11 (November 6, 2020): 440. http://dx.doi.org/10.3390/geosciences10110440.
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Buttresses constitute a spatial supporting construction (SSC) that can convey large loads coming from the pressure of unstable soil on deeper, more stable layers to make it safer with respect to the load-bearing capacity. They make the counteraction against the pressure, which initiates sliding when the forces to move the landslide body, not balanced by the internal frictional forces in the soil. Some specific features of known construction elements were used in the buttress, such as sheet pile walls and drilled piles. Although beneficial in this case, the specific shape of the axis of the wall made from piles and sheets formed a wave created from circle sections (in plan view). Thus, a stable steel buttress was formed. The interaction of the buttress with the soil mass pressure over it, which stabilises the landslide mass, was considered. To further strengthen the buttress, a reinforced concrete slab was added on the upper edge of the thin walls of sheets and piles, thereby integrating and stiffening the whole structure. The application of the concrete slab enabled the use of the stabilisation role of additional forces (become from its weight and above laysoil)to stabilise the buttress. The results of this study achieved a substantial stabilising effect, increasing maximal forces reacting against the pressure of the unstable soil block. Assumptions madeand the applied calculations confirm thestability of the buttress (by increasing the stability of the whole slump block of landslide) are described. Two cases are presented to illustrate the stabilisation and control of movement in which the block body moves along inadvance of the determined slip surface.
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Clancy, Andrew. "The casual buttress." Architectural Research Quarterly 17, no. 1 (March 2013): 92–96. http://dx.doi.org/10.1017/s1359135513000390.
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Jackson, Roger P., and Anne C. McManus. "The Iliac Buttress." Spine 18, no. 10 (August 1993): 1318–28. http://dx.doi.org/10.1097/00007632-199308000-00011.
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Roy, Sanjoy, Yuexi Wang, Rajesh Mallampati, and Stephen Johnston. "Surgical Outcomes, Health Care Utilization, and Costs Associated with Staple Line Buttressing Among Primary Sleeve Gastrectomy Patients." Obesity Surgery 30, no. 12 (September 10, 2020): 4935–44. http://dx.doi.org/10.1007/s11695-020-04917-2.
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Abstract Purpose Staple line buttressing is a method of reinforcing surgical staple lines using buttress materials. This study evaluated surgical outcomes, hospital utilization, and hospital costs associated with staple line buttressing among patients who underwent primary laparoscopic sleeve gastrectomy (PLSG) in the United States. Methods This was a retrospective cohort study using Premier Healthcare Database data from January 1, 2012 to December 31, 2017. Patients aged ≥ 18 years who underwent PLSG were selected and assigned to buttress or non-buttress cohorts based on the use of buttress material during their hospitalization for PLSG (index). Propensity score matching (PSM) was conducted to balance patient demographic and clinical characteristics between the cohorts. Generalized estimating equation models were used to compare the clinical and economic outcomes of the matched buttress and non-buttress users during the index hospitalization. Results A total of 38,231 buttress and 27,349 non-buttress patients were included in the study. After PSM, 24,049 patients were retained in each cohort. Compared with non-buttress cohort, the buttress cohort patients had a similar rate of in-hospital leaks (0.28% vs 0.39%; p = 0.160) and a lower rate of bleeding (1.37% vs 1.80%, p = 0.015), transfusion (0.56% vs 0.77%, p = 0.050), and composite bleeding/transfusion (1.57% vs 2.04%, p = 0.019). Total costs ($12,201 vs $10,986, p < 0.001) and supply costs ($5366 vs $4320, p < 0.001) were higher in the buttress cohort compared with the non-buttress cohort. Conclusions Staple line buttressing was associated with an improvement in complication rates for bleeding and transfusion. Total and supply costs were higher in the buttress cohort, necessitating further research into cost-effective buttressing materials.
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Zhao, Guanglei, Changquan Liu, Kangming Chen, Jinyang Lyu, Jie Chen, Jingsheng Shi, Feiyan Chen, et al. "Nonanatomical Reduction of Femoral Neck Fractures in Young Patients (≤65 Years Old) with Internal Fixation Using Three Parallel Cannulated Screws." BioMed Research International 2021 (January 4, 2021): 1–12. http://dx.doi.org/10.1155/2021/3069129.
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Purpose. The study is aimed at investigating the association between different reduction classifications (anatomic reduction, positive buttress position reduction, and negative buttress position reduction) and two end points (complications and reoperations). Methods. The study retrospectively analyzed 110 patients undergoing internal fixation with three parallel cannulated screws from January 2012 to January 2019 in Huashan Hospital. Based on the principles of the “Gotfried reduction,” all enrolled patients were divided into three groups: anatomic reduction, positive buttress position reduction, and negative buttress position reduction intraoperatively or immediately after surgery. Clinical characteristics including age, sex, side, Garden classification, Pauwels classification, fracture level, reduction classification, Garden alignment index angles, cortical thickness index (CTI), tip-caput distance (TCD), angle of the inferior screw, and the two ending points (complications and reoperations) were included in the statistical analysis. The Mann-Whitney U -test, the chi-square test, Fisher’s exact test, and multiple logistic regression analysis were used in the study. Results. Of the 110 patients included in our study, the mean ± standard deviation SD of age was 51.4 ± 10.4 years; 41 patients showed anatomic reduction, 35 patients showed positive buttress position reduction, and 34 patients showed negative buttress position reduction. For the outcomes, 24 patients (anatomic reduction: 6 [14.6%]; positive buttress position reduction: 5 [14.3%]; negative buttress position reduction: 13 [38.2%]) had complications, while 18 patients (anatomic reduction: 5 [12.2%]; positive buttress position reduction: 3 [8.6%]; negative buttress position reduction: 10 [29.4%]) underwent reoperations after surgery. In the multivariate logistic regression analysis of complications, negative buttress position reduction (negative buttress position reduction vs. anatomic reduction, OR = 4.309 , 95 % CI = 1.137 to 16.322 , and p = 0.032 ) was found to be correlated with higher risk of complications. The same variable (negative buttress position reduction vs. anatomic reduction, OR = 5.744 , 95 % CI = 1.177 to 28.042 , and p = 0.031 ) was also identified as risk factor in the multivariate logistic regression analysis of reoperations. However, no significant difference between positive reduction and anatomical reduction was investigated in the analysis of risk factors for complications, not reoperations. Conclusion. Positive buttress position reduction of femoral neck fractures in young patients showed a similar incidence of complications and reoperations compared with those of anatomic reduction. For irreversible femoral neck fractures, if positive buttress position reduction has been achieved intraoperatively, it is not necessary to pursue anatomical reduction; however, negative reduction needs to be avoided.
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Ferretti, Elena. "Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons." European Journal of Engineering and Formal Sciences 2, no. 3 (December 1, 2018): 6–16. http://dx.doi.org/10.2478/ejef-2018-0012.
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Abstract One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.
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Ferretti, Elena. "Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons." European Journal of Engineering and Formal Sciences 2, no. 3 (December 29, 2018): 7. http://dx.doi.org/10.26417/ejef.v2i3.p7-17.
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One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.
Dissertations / Theses on the topic "Buttress"
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Fekadu, Robel Tekeste, and Sujata Kayastha. "Safety Assessment of Cracked Buttress Dams." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284527.
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Most of the concrete buttress dams in Sweden were built from the 1950s till the1980s based on the traditional method of analyses. Those structures are reinforced and heavy in structure. Their height to thickness ratio being large makes them prone to crack during their lifespan. The presence of these cracks make the reinforcements used in the buttress dam susceptible to corrosion due to the water entering through the cracked areas. Therefore, studying the effect of cracks and corrosion regarding the safety of dams is important and should be carried out before the dams fail to function. However, only limited researches have been conducted to address these issues. The main goal of this project is to evaluate if the traditional method of analysis were sufficient to capture the failure modes of the dam before and after the occurrence of cracks and corrosion of the reinforcement. In the traditional method, the analytical stability calculations for the factor of safety of sliding and overturning are computed separately. However, in reality, those two failure modes do not occur separately but in combined mode. Therefore, to study this matter, two case studies were considered. In these studies, both finite element analysis (FEA) and analytical calculations were performed to investigate the failure modes. Moreover, this project assesses the influence of cracks and corrosion of reinforcements in the factor of safety. And, the software that was used to carry out the FE analyses were COMSOL and Abaqus. And alongside to FE software, MATLAB was used to carry out the analytical calculations. The results from the analyses showed that the combined failure modes in FE-analyses were the mode of failure of the buttress dams in all cases. Therefore, the analytical calculations were not sufficient to capture the failure modes. Furthermore, the reinforcements that were incorporated in the dam were observed to have a significant effect on the factor of safety depending on the patterns of the cracks. Similarly, the corrosion of the reinforcement had severe effects on the factor of safety based on the crack patterns. Based on the findings from the project, the combined failure mode from FE analysis the governing failure mode, and therefore, traditional analytical methods should be carried out to help evaluate those FE analyses but not to capture the actual failure modes. Besides, the incorporated reinforcements and their corrosion had notable influences on the safety factor of dams which should be investigated carefully.De flesta betonglamelldammar i Sverige byggdes under 1950 - 80-talet baserat påden traditionella analysmetoden. Dessa strukturer är armerade och tunga. Derashöjd-tjocklek förhållande är stor nog för att de ska vara benägna att spricka underderas livstid. Uppkomsten av dessa sprickor utsätter armeringen i lamelldammar förkorrosion på grund av att vattnet tränger in genom dessas sprickor. Därför är detytterst viktigt att studera effekter av sprickor och medföljande korrosion avseendedammsäkerhet och bör utföras innan dammarna är ur funktion. Trots vikten avdetta problem, har endast begränsade studier genmfört för att hantera dessa frågor.Huvudmålet med detta examensarbete är att utvärdera den traditionellaanalysmetodens kapacitet att fånga dammens brottillstånd före och efteruppkomsten av sprickor och armeringskorrosion. I den traditionella metoden utförsde analytiska stabilitetsberäkningar av säkerhetsfaktorn för glidning och stjälpningseparat. Men i verkligheten förekommer inte dessa två fenomen separat utan ikombinerat form. För att studera detta fenomen beaktades därför två fallstudier. Ibåda fallen utfördes finita element metod (FEM) och analytiska beräkningar föratt utvärdera brottillstånd. Dessutom utvärderas påverkan av sprickor ocharmeringskorrosion på säkerhetsfaktorn. Programvaran som användes för attutföra FE-analyserna var COMSOL och ABAQUS. Analytiska beräkningarutfördes i MATLAB.Resultaten från analyserna visade att ett kombinerat brottillstånd uppstod iFE-analyserna av lamelldammarna i samtliga studerade fall. Därmed är de utfördaanalytiska beräkningar inte tillräckliga för att fånga brottillståndet. Vidareobserverades att armeringar hade betydande inverkan på säkerhetsfaktornberoende på sprickmönstren. På liknande sätt hade armeringskorrosion signifikantinverkan på säkerhetsfaktorn beroende på sprickmönstren.Utifrån resultatet av FE-analyserna kan man konstatera att den kombineradebrottmoden var det avgörande brottillståndet, och därför bör traditionellaanalysmetoder utföras för att stödja utvärderingen av dessa FE-analyser men inteför att erhålla de faktiska brottillstånd. Dessutom, det kunde observeras attarmering och armeringskorrosion har betydande påverkan på säkerhetsfaktorn avdammar och bör undersökas noggrant.
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Forsgren, Erik, and Isak Berneheim. "Behavior of Swedish Concrete Buttress Dams at Sesmic Loading." Thesis, KTH, Betongbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189237.
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The aim of the thesis is to study the response of Swedish buttress dams if they are subjected to an earthquake of relevant magnitude to Sweden. Swedish dams are evaluated for an extensive amount of load cases, but not for earthquake loading. Therefore, it is not known how the Swedish buttress dams would respond during such loading. Earthquake engineering is practised only to a marginal extent in Sweden due to a low risk of major earthquakes. In fact, an earthquake hazard zonation map that provides data for earthquake resistant design, does not even exist for Sweden. Therefore, part of the thesis is aimed at acquiring data from alternative sources to enable seismic evaluation. The effect of earthquakes on Swedish buttress dams are analysed through case studies. The case studies are performed with numerical analysis using the commercial finite element program Brigade Plus. The case studies are performed on two buttress dam models that were selected based on an inventory of Swedish buttress dams. In the case studies, the dam models are evaluated for the Safety Evaluation Earthquake (SEE), which correspond to 10 000 years return period. At the SEE event, the Peak Ground Acceleration (PGA), is also related to the geographical location of a dam. The envelope of available PGA in Sweden was used in the case studies to cover the spectrum of PGA. The response of the dams to the lowest value of PGA is insignificant and the dams are essentially unaffected. However, for the highest value of PGA the responses indicates that the concrete of the dams is severely cracked and that the ultimate capacity of the reinforcement may be exceeded. Hence, it is concluded that the geographical location of a Swedish dam is highly influential on the response to earthquake loading.Syftet med denna uppsats är att analysera effekten på svenska betonglamelldammar i det fall de utsätts för en jordbävning av relevant magnitud för Sverige. Svenska dammar har blivit utvärderade för ett stort antal lastfall, dock ej för jordbävningslaster. Det är därför inte känt hur svenska betonglamelldammar uppträder under sådana laster. Jordbävningsdimensionering tillämpas endast marginellt i Sverige eftersom det föreligger låg risk för kraftfulla jordbävningar. Faktum är att en zonindelningskarta över jordbävningsrisk för byggnadsdimensionering inte ens existerar i Sverige. Därför dedikeras en del av uppsatsen till att hitta data från alternativa källor för seismisk utvärdering. Effekten av jordbävningar på svenska betonglamelldammar analyseras genom fallstudier. Dessa är genomförda baserat på numerisk analys med det kommersiella finita element programmet Brigade Plus. Analyserna är baserade på två utvalda betonglamelldammodeller som valdes genom en inventering av svenska betonglamelldammar. I fallstudien utvärderas dammarna för en Säkerhet Utvärderings Jordbävning (SUJ), denna motsvaras av 10 000 års återkomsttid. Vid en SUJ relateras den Maximala Mark Accelerationen (MAA) även till det geografiska läget av en damm. Ytterlighetsvärdena av tillgänglig MMA värden i Sverige användes i fallstudien för att täcka in hela spektrumet. Effekten av det lägsta MMA värdet på dammarna är obetydlig och dammarna kan anses i stort sett opåverkade. Det högsta värdet av MMA indikerar dock att dammarnas betong utsätts för stor uppsprickning och att kapaciteten av armeringen överskrids. Det kan därmed fastslås att det geografiska läget av en damm har stort inflytande över vilken effekt som kan förväntas vid en jordbävning
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Ulfberg, Adrian. "Probabilistic non-linear finite element analysis of concrete buttress dams." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72701.
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Assessment of concrete buttress dams today consists of using analytical methods to investigate the stability in different failure modes. However, they simplify the problem at hand and neglect certain important features linked to geometry and thus not truthfully appraise the structures real stability. This could be economically costly in assessments of both existing dam structures as this would eventually lead to unwarranted rehabilitation. The same can be said for dams under design. Kalhovd dam is a concrete buttress dam that has recently undergone assessment where certain sections proved unstable in either failure mode. This study focused specifically on a buttress, numbered 49, of said dam which was deemed in the assessment to be unstable in the overturning and sliding failure mode. The methodology used was to assess and compare stability for different methods of calculation, meaning analytical versus numerical analysis. The numerical analysis was performed with two-dimensional finite element analyses in a commercial FEM-software called ATENA which focuses on reinforced concrete structures. The numerical models made, were then probabilistically analysed by randomizing various material parameters to see their effect on stability. Some FEA models discarded the conventional way of modelling loads, as required by standards, to more realistically portray load actions on dams based on historical measurement. Results from this study showed dissimilarity of stability for buttress 49 depending on which method of analysis was performed. Analytical methods proved to yield the most conservative results and concluded the structure unsafe, while including an accurate representation of the geometry in FEA models improved the stability such that it can be considered stable against load actions stated in guidelines. Furthermore, material parameters randomized in the probabilistic analysis substantiated that various concrete variables had relatively little effect on structural overall strength in the most common failure modes.
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Svensen, Daniel. "Numerical analyses of concrete buttress dams to design dam monitoring." Thesis, KTH, Betongbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189250.
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Old concrete buttress dams are sensitive to cracking if exposed to large temperature variations. The cracks can make dams sensitive to failure, depending on the size and location of the cracks. These problems can be overcome by lowering the temperature variations and stabilizing the dams. Insulation walls can be built to lower the temperature variations, and the area inside the insulation wall can be climate controlled to ensure a constant temperature. Stabilizing measures could be installing tendons, anchoring monoliths to the foundation or to keep parts of the monolith together. However, the best way to make sure the dam is functioning as expected is to monitor the behavior of the dam through different sensors. The sensors should be connected to some kind of dam monitoring software, which can indicate whether the dam is going to fail in a near future. For this to work, some kind of alert and alarm values has to be determined. The main purpose for this project is to develop a finite element model that could be used to simulate the real behavior of a concrete buttress dam and predict the future behavior of the dam. This makes it possible to determine alert and alarm values for monitoring equipment installed on the dam. Some steps are necessary to be able to create a finite element model representing the real behavior and to predict the future behavior of a dam. A first step is calibration of the model against real measurements, and during the calibration process it is important to evaluate the predictions made. A second step is to determine the normal variation in the behavior of the dam. A last step is to define suitable alert and alarm values, where the alert values are based on the normal variation of the dam and the alarm values are based on failure analyses. The results show that it is possible to calibrate a finite element model with sufficient accuracy in order for it to be used for predictions of the dams behavior. The results show two failure modes of the concrete buttress dam which deviate from previous research, where post-tensioned tendons were not included. From the results, information is given about where to place sensors to be able to capture a failure, how well the finite element model is calibrated, and what the alarm values should be. Furthermore, the results show that the evaluation of predictions made in the calibration process is of utmost importance to achieve a model representing the real behavior.Gamla betonglamelldammar är känsliga för sprickbildning om de utsätts för stora temperaturvariationer. Sprickor kan göra dammarna känsliga för brott, beroende på storlek och placering av sprickorna. Dessa problem kan övervinnas genom att sänka temperaturvariationerna och stabilisera dammarna. Isoleringsväggar kan byggas för att sänka temperaturvariationerna, och området innanför isoleringsväggen kan klimatkontrolleras för att säkerställa en konstant temperatur. Stabiliserande åtgärder skulle kunna vara att installera spännkablar, förankring av monoliten till berggrunden eller att hålla ihop delar av monoliten. Emellertid är det bästa sättet att se till dammen fungerar som förväntat för att övervaka beteendet hos dammen genom olika sensorer. Givarna borde anslutas till någon form av programvara för dammövervakning, som kan indikera om dammen kommer att gå till brott inom en snar framtid. För att detta ska fungera måste någon form av mjuka och hårda larmvärden bestämmas. Huvudsyftet för detta projekt är att skapa en finit elementmodell som kan användas för att simulera det verkliga beteendet hos en betonglamelldamm och förutsäga framtida beteende av dammen för att kunna bestämma mjuka och hårda larmvärden för vald övervakningutrustning på dammen. Några steg är nödvändiga för att kunna skapa en finit elementmodell som representerar det verkliga beteendet och göra det möjligt att förutsäga det framtida beteendet av en damm. Ett första steg är kalibrering av modellen mot riktiga mätningar och under kalibreringsprocessen är det viktigt att utvärdera predikterade värden. Ett andra steg är att bestämma den normala variationen av dammens beteende. Ett sista steg är att definiera lämpliga värden för mjuka och hårda larmvärden, där de mjuka värdena baseras på dammens normala variation och de hårda larmvärdena på brottsanalyser. Resultaten visar att det är möjligt att kalibrera en finit elementmodell med tillräckligt god noggrannhet att den kan användas för prediktering av dammens beteende. Resultaten visar två brottmoder av betonglamelldammen som skiljer sig från tidigare studier där spännkablar inte hade inkluderats. Från resultaten ges information om var sensorer ska placeras för att kunna fånga ett brott, hur väl finita elementmodellen kalibrerats, och vilka de mjuka och hårda larmvärdena bör vara. Dessutom visar resultaten att utvärderingen av predikteringar som gjorts i kalibreringsprocessen är av yttersta vikt för att uppnå en modell som representerar det verkliga beteendet.
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Hansen, Christel Dorothee. "The characterisation of an openwork block deposit, northern buttress, Vesleskarvet, Dronning Maud Land, Antarctica." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013138.
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Investigating openwork block accumulation has the potential to further our understanding of rock weathering, the control of geological structure on landforms, the production of substrates for biological colonisation and the impacts of climate change on landform development and dynamics. Various models for the development of these landforms have been proposed. This includes in situ weathering, frost heave and wedging. Furthermore, it has been suggested that cold-based ice has the potential to preserve these features rather than to obliterate them. Blocky deposits are also frequently used as proxy evidence for interpreting palaeoclimates. The morphology and processes acting on a blockfield located on the Northern Buttress of the Vesleskarvet Nunataks, Dronning Maud Land, Antarctica (2°W, 71°S) were investigated and characterised. Given block dimensions and orientations that closely resembled the parent material and only small differences in aspect related characteristics observed, the blockfield was found to be autochthonous with in situ block production and of a young (Holocene) age. Small differences in rock hardness measurements suggest some form of aspect control on rock weathering. South-facing sides of clasts were found to be the least weathered. In comparison, consistently low rock hardness rebound values for the north-facing aspects suggest that these are the most weathered sides. Additional indicators of weathering, such as flaking and pitting, support analyses conducted for rock hardness rebound values. Solar radiation received, slope gradients and snow cover were found to influence weathering of clasts across the study site. Furthermore, ambient temperatures and wind speed significantly influenced near-surface ground temperatures dynamics. However, the lack of a matrix and paucity of fine material in textural analyses suggest a limited weathering environment. It is suggested that the retreat of the Antarctic ice sheet during the last LGM led to unloading of the surface, causing dilatation and subsequent fracturing of the bedrock along pre-existing joints, leading to in situ clast supply. Subsequent weathering and erosion along other points or lines of weakness then yielded fines and slight edge rounding of clasts.
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Fu, Chaoran, and Bjartmar Hafliðason. "Progressive failure analyses of concrete buttress dams : Influence of crack propagation on the structural dam safety." Thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169707.
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Concrete buttress dams are the most common type of concrete dams for hydropower production in Sweden. Cracks have been observed in some of the them. However, only limited research has been made concerning the influence of these cracks on the structural dam safety. In conventional analytical stability calculations, a concrete dam is assumed to be a rigid body when its safety is verified. However, when cracks have been identified in a dam structure, the stability may be influenced and hence the information of cracks may need to be included in the stability calculations. The main aim of this project is to study how existing cracks and further propagation of these cracks, influence the structural dam safety. Another important topic was to study suitable methods to analyse a concrete dam to failure. In addition, a case study is performed in order to capture the real failure mode of a concrete buttress dam. The case study that has been studied is based on a previous project presented by Malm and Ansell (2011), where existing cracks were identified in a 40m high monolith, as a result from seasonal temperature variations. Two similar models are analysed where one model is defined with an irregular rock-concrete interface, and the other with a horizontal interface. Analyses have been performed on both an uncracked concrete dam but also for the case where information regarding existing cracks, from the previous project, have been included in order to evaluate the influence of cracks on the dam safety. The finite element method has been used as the main analysis tool, through the use of the commercially available software package Abaqus. The finite element models included nonlinear material behaviour and a loading approach for successively increasing forces called overloading, when performing progressive failure analyses. The results show that existing cracks and propagation of these resulted, in this case, in an increased structural safety of the studied dam. Furthermore, an internal failure mode is captured. The irregular rock-concrete interface has a favourable effect on a sliding failure and an unfavourable effect on an overturning failure, compared to the case with the horizontal interface. Based on the results, the structural safety and the failure mode of concrete buttress dams are influenced by existing cracks. Although an increased safety is obtained in this study, the results do not necessarily apply for other monoliths of similar type. It is thus important that existing cracks are considered in stability analyses of concrete buttress dams.Lamelldammar är den vanligaste typen av betongdammar för vattenkraft produktion i Sverige. I vissa av dessa har sprickbildning observerats. Begränsad forskning har gjorts på hur dessa sprickor påverkar dammens säkerhet. I de vedertagna analytiska stabilitetsberäkningarna antas att betongdammar agerar som en stel kropp när man verifierar dess säkerhet. Befintliga sprickor i en damm kropp kan dock påverka dess stabilitet och kan därför behöva beaktas i stabilitetsberäkningarna. Huvudsyftet med detta projekt är att studera hur befintliga sprickor och dess propageringen påverkar dammsäkerheten. Ett annat viktigt syfte är att studera lämpliga metoder för att analysera en betongdamm till brott. Dessutom, genomförs en fallstudie i syfte att analysera ett verkligt brottförlopp av en lamelldamm. Fallstudien som utförs i detta projekt, baseras på ett tidigare projekt utfört av Malm and Ansell (2011), där befintliga sprickor identifierades i en monolit på 40m som ett resultat av temperaturvariationer. Två modeller med snarlik geometri har analyserats, där den ena är definierad med en med oregelbunden kontaktyta mellan berg och betong och den andra med en horisontell kontaktyta. Analyserna har utförts på dels en osprucken damm men även där information om befintliga sprickor från det tidigare projektet beaktas, i syfte att jämföra inverkan av sprickor på dammsäkerheten. Finita element metoden har använts som verktyg vid dessa analyser, genom det kommersiellt använda programmet Abaqus. De finita element modellerna inkluderar icke-linjära material egenskaper hos betong och armering samt baseras på en metod för successiv belastning, som kallas 'overloading', vid analys av brottförloppet. Resultatet visar att befintliga sprickor och propageringen av dessa i detta fall kan leda till ökad säkerhet hos den studerade dammen jämfört mot fallet utan beaktande av sprickbildning. Utöver detta fångas även ett inre brottmod. Den oregelbundna kontaktytan mellan betongen och berget har en gynnsam effekt vid ett glidbrott men en ogynnsam inverkan vid ett stjälpningsbrott, i jämförelse med fallet med en horisontell kontaktyta. Baserat på dessa resultat så påverkas dammens säkerhet och brottetförloppet hos lamelldammen utav befintliga sprickor. Även om en ökad säkerhet fås i denna studie är det inte säkert att detta stämmer för andra monoliter av samma slag. Dock är det viktigt att hänsyn tas till befintliga sprickor i stabilitets analyser av lamelldammar.
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Falcão, de Queiroz Daniel. "An alarm system for pore pressure measurements in the foundation ofconcrete dams : a case study of Storfinnforsen buttress dam." Thesis, KTH, Jord- och bergmekanik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233461.
Full textAbstract:
Concrete buttress dams are relatively light structures and less demandingon foundations; because of that, they may have problems with upliftforces and horizontal joints in the area of the dam´s foundation maypresent a failure mode through sliding. The Storfinnforsen dam, thelargest concrete dam in Sweden, had its foundation studied recently andthe discovery of sub-horizontal joints in the bedrock led to the necessityof having the safety of the dam foundation to sliding assessed.The safety is dependent on the pore pressure, which can vary throughtime. The implementation of an alarm system to monitor and assess thevalues of the pore pressure is necessary to improve the dam´s operation.In this thesis, a new system on how to define alarm limits for measuredpore pressures is suggested.The proposed alarm system will monitor the pore pressure of the joint,calculate the safety factor against sliding, compare it to the alarm limits ofthe system (adopted from RIDAS) and present countermeasures to theproblem.The analysis and implementation of the alarm system on monolith 42 ofStorfinnforsen showed that it does not comply with the Swedishguidelines with respect to sliding stability, but the measured porepressures are low enough to allow the creation of an alarm system thatwill monitor the pore pressure continuously. Furthermore, thecharacteristics of the local geology exclude any quick development of porepressure allowing countermeasures to be applied.However, further research on the definition of alarm limits for this kindof problem is needed.Lamelldammar av betong är relativt lätta konstruktioner med mindrepåkänningar på grunden jämfört med konventionellagravitationsdammar. Till följd av detta är de också känsliga för upptryck.I kombination med förekomsten av sub-horisontella sprickplan iberggrunden kan detta utgöra en risk för glidning. Vid Storfinnforsensbetongdamm, vilken är Sveriges största lamelldamm, har undersökningarav berggrunden genomförts. I samband med dessa undersökningaridentifierades sub-horisontella sprickplan i berggrunden ochmonoliternas glidstabilitet har därför analyserats med avseende påglidning. Dränage har även borrats och portrycksmätare installerats föratt övervaka portrycket i berggrunden.Portrycket, och därmed dammens säkerhet mot glidning, kan emellertidvariera över tid. Det är därför nödvändigt att utveckla och implementeraett alarmsystem för att övervaka portrycket och säkerställa dammenssäkerhet. I följande examensarbete har ett nytt system utvecklats för attdefiniera alarmgränser för uppmätta portryck. I det föreslagnaalarmsystemet övervakas portrycket över sprickplanen, säkerhetsfaktornmot glidning beräknas och jämförs mot gränser baserade på acceptablasäkerhetsfaktorer från RIDAS. Om uppmätta portryck överstigeralarmgränserna implementeras fördefinierade åtgärder.I detta arbete implementerades alarmsystemet på monolit 42 iStorfinnforsens lamelldamm. Resultaten från en inledandestabilitetsanalys visade att säkerhetsfaktorn mot glidning inte uppfyllerställda krav enligt RIDAS riktlinjer. De uppmätta portrycken äremellertid tillräckligt låga för att möjliggöra användningen av ettalarmsystem som övervakar portrycken kontinuerligt och därmedsäkerställer att säkerheten mot glidning uppfylls. Om portrycken skulleöverstigas ges förslag på möjliga åtgärder som kan genomföras för attsänka portrycken. Vidare indikerar de lokala geologiska förhållandena attVsnabba höjningar av portrycken till följd av exempelvis urspolning avfyllnadsmaterial från sprickplan är osannolika, vilket möjliggörimplementering av de fördefinierade åtgärderna om portrycket skullestiga. Vidare forskning rekommenderas emellertid på hur snabbtportrycken kan stiga till följd av olika scenarier såsom nedbrytning avinjekteringsridåer.
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McCormack, Thomas C. "A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results." PDXScholar, 1987. https://pdxscholar.library.pdx.edu/open_access_etds/3715.
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The P-y curve, used in current practice as an efficient Iine-load vs. soi displacement model for input into the finite difference method of laterally loaded pile analysis, is extended in this study for use with cohesionless soils in diaphragm wall analysis on the Personal Computer with the BMCOL7 program. An analogous W-y curve is proposed, an elastic-plastic model with line-load limits developed from classical earth-pressure theories.
A new formula for predicting a horizontal walI modulus for cohesionless soiIs from the pressuremeter modulus is developed for use in predicting the displacements on the W-y curves. The resulting modulus values are shown to yield reasonable displacements values.
A new procedure for modeling preloaded tie-back anchors and staged excavation for diaphragm walIs was developed, utiIizing multiple computer runs, updated the W-y curves, and superposition of deflections.
These new developments were applied to a parametric study of a deflection-critical section of the new Bonnevilie Nav-Lock Buttress Diaphragm Wall, for which extensive high-quality pressuremeter test results were available. Deflection curves of the wall are presented, showing the effect of variations in anchor preload, walI cracking, anchor slip, at-rest pressure, and soiI modulus.
The results indicate that preloading will reduce wall deflections by at least 4-fold, but that wall cracking can potentially double deflections. Safety factors against passive soil failure were determined to be about 5 at anchor preload, and more than 40 after fulI excavation.
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Maegan, Annette Fitzgerald. "Contextualizing chimpanzee research within the socioecological landscape of the Forestière region of the Republic of Guinea, Africa." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/265178.
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付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院京都大学
新制・課程博士
博士(理学)
甲第23406号
理博第4741号
新制||理||1680(附属図書館)
京都大学大学院理学研究科生物科学専攻
(主査)教授 平田 聡, 教授 村山 美穂, 教授 伊谷 原一
学位規則第4条第1項該当
Doctor of Science
Kyoto University
DGAM
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Zuwak, Imal, and Wasseem Kordoghly. "Numerical study of the effect of thermal ice loads on concrete dams." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278545.
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It is essential to understand the mechanics of ice load and how it affects concrete dams located in a cold climate, such as Sweden, where the temperature becomes sufficiently cold to freeze the surface of the reservoir. The purpose of this thesis is to study ice load distribution along concrete dams, and its response during the application of an ice load. Two types of concrete dams were analysed, an arch dam and a buttress dam. For these dams, the influence from different parameters on the ice load distribution along the dams is studied. In addition to this, a study on how the ice load affects dam stability had also been performed. Stability analyses based on the finite element method were performed using both linear and nonlinear formulation of the interaction behaviour between the base of the dam and the underlying rock. A parametric study of ice sheet expansion on different dam types and geometries were performed. The expansion of the ice sheet was assumed to either be caused by a constant temperature 15 ˚C uniformly distributed over the ice thickness, or by a temperature gradient from 15 ˚C at the top surface of the ice sheet and 0 ˚C at the bottom. The parametric study also includes an investigation about influence of the shape of the reservoir beaches, where it either had a perpendicular shape towards the surface of the dam, or it had an angle of 30˚ with the dam surface. In the linear stability analysis, the structure continued to deform with increasing of the resultant pressure until it reached nonlinearity. The dam deflection had a linear relation with the applied ice load force until it reached the point when structure behaviour was nonlinear. The structure failed due to sliding, overturning or combination of both sliding and overturning. A material failure can also occur if the nonlinear material behaviour is considered, however this was not considered in this study. The parametric study showed that the ice load distribution was less near the beaches, and the distribution of the load on the concrete dam was higher near the top surface of the ice sheet. It was also shown in the study that the distribution of the ice load along the dam was as a cosine function where it had the maximum value at the buttress and the minimum at monolith connections. The result also showed that the load distribution over the thickness of the ice sheet was the same along the dam, regardless of the shape of the beaches or the length of the ice sheet.Det är viktigt att förstå hur islasten beter sig och hur den påverkar betongdammar som är belägna i kallt klimat, som t.ex. Sverige, där temperaturen blir tillräckligt låg för att frysa ytvattnet i en flod. Syftet med detta examensarbete är att studera isbelastningsfördelningen längs en betongdamm och dess respons under en belastningen. Två olika typer av betongdammar har analyserats, vilka är valvdamm samt lamelldamm. För dessa, studerades det hur olika parametrar påverkar lastfördelningen från istrycket längsmed dessa dammar. Slutligen har det studerats hur islasten påverkar dammsäkerheten och risken för dammbrott. Inverkan från interaktionen mellan dammen och det underliggande berget som linjär eller olinjärt har studerats i stabilitetsanalyser baserade på finita elementmetoden. En parameterstudie har också genomförts för olika dammtyper och geometrier där islasten orsakades av en expansion av isytan. Denna expansion antogs vara orsakad av antingen av en jämn fördelad temperatur över istjockleken på 15 ˚C, eller en temperaturgradient över istjockleken med +15 ˚C på den övre ytan och 0 °C vid isens bottenyta. Den parametriska studien beaktar även inverkan från utformningen av stränderna, där den har definierats som antingen vinkelrät mot dammen eller med en lutande vinkel på 30 grader. I fallet med linjära stabilitetsanalyser kommer konstruktionen att fortsätta att deformeras som ett resultat av ökande resulterande tryckkraft. Dammens deformation har ett linjärt förhållande med den applicerade islasten till dess att den når en punkt då strukturens beteende övergå till olinjärt. Strukturens brottmod kan uppstå på grund av glidning, stjälpning eller i en kombination av både glidning och stjälpning. materialbrott kan uppstå om icke-lineariteterna beaktas. Dammen gick till brott på grund av glidning, vältning eller i kombinationen av dessa då. Materialbrott kan uppstå om icke-linjära materialmodeller inkluderas, men detta beaktades dock ej i denna studie. Den parametriska studien visar att isbelastningen är mindre nära stränderna och att belastningen på betongdammen är högre vid isens ovanyta. Studien visar att islastfördelningen längsmed dammen liknar en cosinusfunktion som når sitt maximum vid stödskivan och sitt minimum vid monolitanslutningen. Resultatet visar även att islastfördelningen genom islastens tjocklek har samma form längsmed dammen oavsett utformningen av stränder eller istäckets längd.
Books on the topic "Buttress"
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Mot︠s︡onelidze, N. S. Stability and Seismic resistance of buttress dams. Rotterdam: A.A. Balkema, 1987.
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Coombs, Colby. Denali's West Buttress: A climber's guide to Mt. McKinley's classic route. Seattle, WA: Mountaineers, 1997.
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Craniomaxillofacial buttresses: Anatomy and operative repair. New York: Thieme, 2012.
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Swinbank, Jean C. M. Buttress's world guide to abbreviations of organizations. London: Blackie Academic & Professional, 1993.
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A, Buttress F., ed. Buttress's world guide to abbreviations of organizations. London: Blackie Academic & Professional, 1997.
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Pittman, L. M. Buttress’s World Guide to Abbreviations of Organizations. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0093-6.
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Swinbank, Jean C. M., and Henry J. Heaney. Buttress’s World Guide to Abbreviations of Organizations. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2132-3.
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Heyman, Jacques. Arches, vaults, and buttresses: Masonry structures and their engineering. Aldershot, Hampshire, Great Britain: Variorum, 1996.
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Flying buttresses, entropy, and O-rings: The world of an engineer. Cambridge, Mass: Harvard University Press, 1991.
Find full textBook chapters on the topic "Buttress"
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James, Leslie. "A Buttress for the ‘Beacon Light’." In George Padmore and Decolonization from Below, 120–42. London: Palgrave Macmillan UK, 2015. http://dx.doi.org/10.1057/9781137352026_7.
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Ma, Jianfei, Ruoyang Song, Tao Han, Arturo Sanchez-Azofeifa, and Anup Basu. "Poisson Surface Reconstruction from LIDAR for Buttress Root Volume Estimation." In Lecture Notes in Computer Science, 463–71. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-54407-2_39.
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Takahashi, K., and H. Tanaka. "Experimental and Numerical Study on Wave Absorbing Breakwater Using Buttress." In APAC 2019, 979–86. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-15-0291-0_134.
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Feld, Claudia. "Images of Disappearance in Argentina: How Films, Photos, and Television Buttress Memory." In Public Memory, Public Media and the Politics of Justice, 41–64. London: Palgrave Macmillan UK, 2012. http://dx.doi.org/10.1057/9781137265173_3.
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Lim, Aswin, and Chang-Yu Ou. "Performance of Composite Buttress and Cross Walls to Control Deformations Induced by Excavation." In Springer Series in Geomechanics and Geoengineering, 373–76. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97112-4_83.
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Lim, Aswin, and Chang-Yu Ou. "Case Record of a Strut-free Excavation with Buttress Walls in Soft Soil." In Springer Series in Geomechanics and Geoengineering, 142–54. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-6632-0_11.
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Hsieh, Pio-Go, and Shao-Chi Chien. "Numerical Investigation of the Efficiency of Buttress Walls in Reducing the Diaphragm Wall Deflection by Deep Excavation." In Springer Series in Geomechanics and Geoengineering, 676–89. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-6632-0_53.
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"Buttress." In The Visual Dictionary of Architecture, 67. AVA Publishing SA Bloomsbury Publishing Plc, 2008. http://dx.doi.org/10.5040/9781350096462.0054.
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"buttress." In Sir Banister Fletcher Glossary. © the Royal Institute of British Architects (RIBA) and the University of London, 2018. http://dx.doi.org/10.5040/9781350122741.1000356.
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"buttress." In Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 179. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41714-6_23895.
Full textConference papers on the topic "Buttress"
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Haeri, Navid, John S. Lewis, and Brian A. Cornah. "Assessment of Stress Distribution in a Buttress Type Connection for Polyethylene Autoclave Reactor." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97707.
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Background. The authors conducted a study to analyze the stress distribution in an End Cover – Buttress Strap – Cylindrical connection according to Users’ Spec. Materials and methods. The authors created axi-symmetric finite element models in order to demonstrate the reaction loads and stress distribution on contact surfaces as well as stress distribution in the various regions of the model. They applied different design scenarios according to an operational (users’) spec to the models. The parameters investigated were the reaction loads at contact points and local and linearised stresses. Also each individual buttress groove was studied. Ratcheting and fatigue assessment were also addressed aligned with the stress results. Results. The study results showed the behaviour of each buttress element under the operating loads. It also showed the location with the greatest local stress levels as well as the locations most vulnerable to ratcheting and fatigue cracking. A safety margin assessment also was carried out picturing the pressure-temperature enhancement possibilities. Conclusions. The study indicates potential future design options for enhancing buttress type connections. It also contributes to the understanding of existing reactor damage and corrosion assessment, impacts which may be useful in the remaining life assessment and process optimisation. Fracture study also defines the most critical inspection points during the life of the reactor.
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Zhong, Li, Zhang Laibin, Fan Jianchun, Yan De, Li Xiaogang, Tan Shuying, and Jia Haiyan. "Design and Application of Buttress Thread Buckle Marine Conductor." In 2010 International Conference on Digital Manufacturing and Automation (ICDMA). IEEE, 2010. http://dx.doi.org/10.1109/icdma.2010.108.
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Chen, Shong-Loong, Cheng-Tao Ho, Chia-Yu Yeh, and Meen-Wah Gui. "Effectiveness of Buttress and Cross-Wall in Deep Excavations." In Fourth Geo-China International Conference. Reston, VA: American Society of Civil Engineers, 2016. http://dx.doi.org/10.1061/9780784480038.033.
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Tiwari, Binod, and Sergio Duarte. "Performance of Slope Stabilization Works with Drainage and Buttress." In Geo-Congress 2013. Reston, VA: American Society of Civil Engineers, 2013. http://dx.doi.org/10.1061/9780784412787.169.
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Chastain, Jerry T., and Po P. Chang. "Convert a Slab-Buttress Dam to a Gravity Dam." In Waterpower Conference 1999. Reston, VA: American Society of Civil Engineers, 1999. http://dx.doi.org/10.1061/40440(1999)18.
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Ji, Dongyu, and Kelun Wei. "Study on force analysis of single buttress filling slag dam." In 2013 2nd International Symposium on Instrumentation & Measurement, Sensor Network and Automation (IMSNA). IEEE, 2013. http://dx.doi.org/10.1109/imsna.2013.6743278.
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Nie, Ying, Xuepeng Ling, Fenghan Hu, Qingsong Zhang, Xiaofeng Zhao, and Bo Liang. "Research On The Buttress-Warehouse Retaining Wall Based On Centrifugal Model Test." In 2017 3rd International Forum on Energy, Environment Science and Materials (IFEESM 2017). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/ifeesm-17.2018.95.
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Yang, Yucheng, and Qin Ma. "The Effect of Pedicle Screw Thread Shape on the Stress Concentration Under Lateral Bending." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93162.
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Abstract Pedicle screws (PS) are frequently used in medical spinal column fixation. Despite 7 out of 100 pedicle screws fracture inside of the patients’ body and under the claim that lateral bending is the main failure mode, little research has addressed the stress characteristics and the fracture location of the PS under lateral bending. This study focuses on the effect of thread design on the magnitude and location of maximum stress concentration. Four types of thread shapes are considered including V-shape, square-shape, buttress, and reverse buttress. Three-dimensional (3D) finite element (FE) methods are used in this investigation. A load of 150 Newton is applied at the screw head to simulate lateral bending. The models are created in SolidWorks. The 3D FE analysis is performed using the standard coding of ANSYS Workbench 19.1. Based on this study, it is found that the high stress concentration is located at the cortical bone region rather than at the cancellous bone region. Although the general stress patterns are similar, the PS thread shape design and the thread fillet radius may significantly affect on the magnitude and location of maximum stress concentration.
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Galle, Timothy, Wim De Waele, and Patrick De Baets. "Effect of Make-Up on the Structural Performance of Standard Buttress Connections Subjected to Tensile Loading." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97282.
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When establishing oil wells, pipe sections are connected by means of threaded couplings. In an effort to minimize the possibility of failure by jumpout, standard buttress connections were introduced. Part of their strength is directly acquired as a result of radial interference during make-up. This paper discusses the results of a numerical study evaluating the effect of make-up on the performance of a standard 4.5 inch API buttress connection when axial tensile force is applied. In order to characterize the structural performance, the load distribution along the coupling length is evaluated, combined with a parameter defining thread separation. The latter is indicative for jumpout and the tendency of creating a leak path throughout the thread helix. From the results it is clear that relative axial displacement within the coupling occurs, even when made up, because of an initial clearance among the load and stab flanks. This clearance may cause a connection to leak through the thread helix when available thread compound cannot heal this leak path. Despite undesirable effects on the sealability and rigidness of this joint, such a clearance is required to decrease frictional forces during make-up while maintaining the desired radial interference.
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Ansari, Shaheryar, Garni Barkhoudarian, Daniel Kelly, and Chester Griffiths. "A Direct Visualization Approach to Placement of Temporary Sinonasal Buttress in Endonasal Tumor Surgery." In 29th Annual Meeting North American Skull Base Society. Georg Thieme Verlag KG, 2019. http://dx.doi.org/10.1055/s-0039-1677804.
Full textReports on the topic "Buttress"
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Fletcher, Daniel. Improved Buttress Thread Machining for the Excalibur and Extended Range Guided Munitions. Fort Belvoir, VA: Defense Technical Information Center, May 2006. http://dx.doi.org/10.21236/ada482718.
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Kessler, Kenneth J. Jr. Basal Trunk And Buttress Root Injuries May Be Associated With Branch Dieback In Black Oak. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Research Station, 1992. http://dx.doi.org/10.2737/nc-rn-358.
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McCormack, Thomas. A finite difference soil-structure interaction study of a section of the Bonneville Navigation Lock buttress diaphragm wall utilizing pressuremeter test results. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.5599.
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MacLean, Nancy. How Milton Friedman Exploited White Supremacy to Privatize Education. Institute for New Economic Thinking Working Paper Series, September 2021. http://dx.doi.org/10.36687/inetwp161.
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This paper traces the origins of today’s campaigns for school vouchers and other modes of public funding for private education to efforts by Milton Friedman beginning in 1955. It reveals that the endgame of the “school choice” enterprise for libertarians was not then—and is not now--to enhance education for all children; it was a strategy, ultimately, to offload the full cost of schooling onto parents as part of a larger quest to privatize public services and resources. Based on extensive original archival research, this paper shows how Friedman’s case for vouchers to promote “educational freedom” buttressed the case of Southern advocates of the policy of massive resistance to Brown v. Board of Education. His approach—supported by many other Mont Pelerin Society members and leading libertarians of the day --taught white supremacists a more sophisticated, and for more than a decade, court-proof way to preserve Jim Crow. All they had to do was cease overt focus on race and instead deploy a neoliberal language of personal liberty, government failure and the need for market competition in the provision of public education.
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Ebeling, Robert, and Barry White. Load and resistance factors for earth retaining, reinforced concrete hydraulic structures based on a reliability index (β) derived from the Probability of Unsatisfactory Performance (PUP) : phase 2 study. Engineer Research and Development Center (U.S.), March 2021. http://dx.doi.org/10.21079/11681/39881.
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This technical report documents the second of a two-phase research and development (R&D) study in support of the development of a combined Load and Resistance Factor Design (LRFD) methodology that accommodates geotechnical as well as structural design limit states for design of the U.S. Army Corps of Engineers (USACE) reinforced concrete, hydraulic navigation structures. To this end, this R&D effort extends reliability procedures that have been developed for other non-USACE structural systems to encompass USACE hydraulic structures. Many of these reinforced concrete, hydraulic structures are founded on and/or retain earth or are buttressed by an earthen feature. Consequently, the design of many of these hydraulic structures involves significant soil structure interaction. Development of the required reliability and corresponding LRFD procedures has been lagging in the geotechnical topic area as compared to those for structural limit state considerations and have therefore been the focus of this second-phase R&D effort. Design of an example T-Wall hydraulic structure involves consideration of five geotechnical and structural limit states. New numerical procedures have been developed for precise multiple limit state reliability calculations and for complete LRFD analysis of this example T-Wall reinforced concrete, hydraulic structure.