Strut-and-tie modeling (STM) is a versatile, lower-bound (i.e. conservative) design method for reinforced concrete structural components. Uncertainty expressed by engineers related to the implementation of existing STM code specifications as well as a growing inventory of distressed in-service bent caps exhibiting diagonal cracking was the impetus for the Texas Department of Transportation (TxDOT) to fund research project 0-5253, D-Region Strength and Serviceability Design, and the current implementation project (5-5253-01). As part of these projects, simple, accurate STM specifications were developed. This thesis acts as a guidebook for application of the proposed specifications and is intended to clarify any remaining uncertainties associated with strut-and-tie modeling. A series of five detailed design examples feature the application of the STM specifications. A brief overview of each design example is provided below. The examples are prefaced with a review of the theoretical background and fundamental design process of STM (Chapter 2). • Example 1: Five-Column Bent Cap of a Skewed Bridge - This design example serves as an introduction to the application of STM. Challenges are introduced by the bridge’s skew and complicated loading pattern. A clear procedure for defining relatively complex nodal geometries is presented. • Example 2: Cantilever Bent Cap - A strut-and-tie model is developed to represent the flow of forces around a frame corner subjected to closing loads. The design and detailing of a curved-bar node at the outside of the frame corner is described. • Example 3a: Inverted-T Straddle Bent Cap (Moment Frame) - An inverted-T straddle bent cap is modeled as a component within a moment frame. Bottom-chord (ledge) loading of the inverted-T necessitates the use of local STMs to model the flow of forces through the bent cap’s cross section. • Example 3b: Inverted-T Straddle Bent Cap (Simply Supported) - The inverted-T bent cap of Example 3a is designed as a member that is simply supported at the columns. • Example 4: Drilled-Shaft Footing - Three-dimensional STMs are developed to properly model the flow of forces through a deep drilled-shaft footing. Two unique load cases are considered to familiarize the designer with the development of such models. / text

Significant diagonal cracking in reinforced concrete inverted-T straddle bent caps has been reported throughout the State of Texas. Many of the distressed structures were recently constructed and all have been in service for less than two decades. The unique nature of the problem prompted a more detailed look into the design and behavior of such structural components. Strut-and-tie modeling is currently recommended for design of deep (rectangular) beams, but its application to more complex structures has not been fully explored. Due to concerns with current design provisions the application of strut-and-tie modeling to inverted-T beams was investigated along with serviceability-related considerations in this dissertation. An experimental study was conducted in which thirty-three reinforced concrete inverted-T beam tests were conducted. The effects of the following variables were evaluated: ledge depth and length, quantity of web reinforcement, number of point loads, member depth, and shear span-to-depth ratio. A strut-and-tie design method proposed by Birrcher et. al (2009), initially calibrated for compression-chord loaded deep beams, was investigated. It was concluded that the strut-and-tie method was a simple and accurate design method, and it was recommended for use in inverted-T beam design. A vi recommendation was also made for the amount of minimum web reinforcement needed for strength and serviceability considerations. A simple service-load check was proposed for the purpose of limiting diagonal cracking under service loads. Finally, a chart was created to aid in the evaluation of distressed, diagonally-cracked inverted-T bent caps in the field. / text

Bridge bents (deep beams) in the State of Texas have experienced diagonal cracking problems with increasing frequency. These field related issues, taken in combination with discrepancies that exist between design provisions for strut and tie modeling (STM), were the impetus for the funding of the current project. The overall objective of the project was to develop safe and consistent design guidelines in regard to both the strength and serviceability of deep beams. In order to accomplish this research objective and related tasks, a database of 868 deep beam tests was assembled from previous research. Inadvertently, many of the beams in this database were considerably smaller, did not contain sufficient information, or contained very little shear reinforcement. As a result, filtering criteria were used to remove 724 tests from the database. The criteria were chosen to consider only beams that represent bent caps designed in the field. In addition to the 144 tests that remained in the database, 34 tests were conducted as part of the current experimental program resulting in 178 total tests available for evaluation purposes. Two additional tests were conducted on beams without shear reinforcement, thus they did not meet the filtering criteria. However, the results from these tests provided valuable information regarding deep beam behavior. Beams that were fabricated and tested as part of the current experimental program ranged in size from, 36"x48", 21"x75", 21"x42", and 21"x23". These tests represent some of the largest deep beam shear tests ever conducted. STM details that were investigated included: (i) the influence that triaxial confinement of the load or support plate has on strength and serviceability performance; and (ii) the influence that multiple stirrup legs distributed across the web has on strength and serviceability performance. Based on the findings of the experimental and analytical program, a new strut-and-tie modeling procedure was proposed for the design of deep beam regions. The procedure is based on an explicitly defined single-panel truss model with non-hydrostatic nodes. An important aspect of the new STM design methodology is that it was comprehensively derived based on all the stress checks that constitute an STM design. Thus, the new method considers every facet of a STM design. The newly proposed STM procedure is simple, more accurate, and more conservative in comparison with the ACI 318-08 and AASHTO LRFD (2008) STM design provisions. As such, the implementation of the new design provisions into ACI 318 and AASHTO LRFD is recommended. / text

Significant diagonal cracking in reinforced concrete inverted-T (IT) straddle bent caps has been reported throughout the State of Texas. Many of the distressed structures were recently constructed and have generally been in service for less than two decades. The unique nature of the problem prompted a closer look into the design and behavior of such structural components. A preliminary investigation highlighted outdated design requirements and a scarcity of experimental investigations pertaining to inverted-T bent caps. This research project (TxDOT Project 0-6416, Shear Cracking in Inverted-T Straddle Bents) aims to improve current understanding of the behavior of inverted-T caps, while providing updated design provisions. In order to develop strength and serviceability guidelines for inverted-T beams, an extensive experimental program was developed. This series of large scale tests was used to evaluate the strength and serviceability of IT deep beams in relation to the following parameters – shear span-to-depth (a/d) ratio, web reinforcement ratio, ledge height, ledge length, number of point loads, and member depth. This report focuses mainly on results from a first series of tests conducted within this experimental program. / text

No description available.

It has been desirable for years to develop non-intrusive/non-invasiveprocedures to determine the pressures and stresses at various levels andinterfaces in the railroad track structure in order to optimize track designs andimprove subsequent track performance. Recent research has developedsatisfactory procedures for measuring pressures in the track structure at theballast/subballast/subgrade levels using earth pressure cells. The researchreported in this thesis documents the development of a technique for measuringthe pressures in the track, at the rail/tie plate/tie interfaces, using a very thinpressure sensitive Tekscan sensor. The Tekscan Measurement System uses asensor composed of a matrix-based array of force sensitive cells, similar to ministrain gauges, to obtain accurate pressure distributions between two surfaces inthe track. This thesis specifically describes: 1) the optimum procedure to installthe sensors into the track, 2) the recommended practices to effectively collectdata with the software, and 3) the accepted techniques for analyzing the results.Both laboratory calibration and in-track testing have been conducted and theresults are presented. The findings attest to the usefulness and practicality of theprocedure for accurately measuring pressures in railroad tracks. The proceduremay also be applicable for a wide variety of specific track related measurementssuch as validating curve geometric criteria, assessing crossing diamond impactpressures, and evaluating the advantages/disadvantages of various types of tieplates, fastenings and tie compositions.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 172-177).

Abstract Title: Last Exit? A Study of Prison Sentenced Recidivists’ Subsequently Choice to Make Use of Criminals Return Into Society (KRIS) as a Resource in Order to Terminate the Criminal Lifestyle  Author: Jimmy Karlsson  A point of departure for this essay is my and my co-author’s bachelor thesis The Refuse to Walk More Yards Prison Corridor.   The purpose of the present essay is to illuminate in which conditions the organization KRIS (Criminals Return Into Society) develops from being directly or indirectly realizable to being a realized resource for recidivists who have served several prison sentences. The theoretical basis is Caroline Tovatt’s concepts potential, realizable and realized resources combined with Pierre Bourdieu’s capital metaphors and Mark S. Granovetter’s concept of strong and weak ties. To illustrate the process that led the interviewees (which I have interviewed from a life story perspective) to the realization of KRIS as a resource and ultimately the ending of the criminal lifestyle, I have used Helen Rose Fuchs Ebaughs stage theory of the role exit process.   The results indicate that recidivists’ choice to realize the resource KRIS has been occasioned by a specific composition of necessary components and a social capital. The necessary components are represented by negative life experiences which via a transformation in three stages have resulted in making KRIS available as a resource for the interviewees. The social capital in turn, which has to interact with the necessary components, is represented by weak and negative ties subsequently remodeled into positive ones. These ties have paved the way for the interviewees to access the organization. To finally fulfill the role exit process the interviewees have to possess or acquire an embodied cultural capital which allows them to differentiate and maintain all aspects linked to the previous and the current role, both to themselves and also to other individuals.

Made available in DSpace on 2015-03-26T13:54:43Z (GMT). No. of bitstreams: 1 texto completo.pdf: 217799 bytes, checksum: dc5b6c16d985e080faefdc7202d7fbd8 (MD5) Previous issue date: 2009-02-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / It was evaluated the effect of diets with levels crude protein - CP (10, 12, 14 and 16% in dry matter - DM) on the performance and efficiency of utilization of nutrients in dairy cows. Twelve Holstein cows with average body weight (BW) of 570 kg, milk production (MP) of 13 kg/day were distributed in three 4x4 Latin squares. The feed consisted of 75% of corn silage and 25% of concentrate. Increased (P <0.05) linear in the intake of all components of the diet, except for total carbohydrates and non- fibrous carbohydrates (NFC), which decreased (P <0.05) linearly with the increase CP in the diet. The intake of total digestible nutrients (TDN) presented quadratic effect (P <0.05) with increase of CP, and estimated the maximum value of 10.13 kg / day at level of 15.62% of CP in the diet. The digestibility of CP, ether extract, neutral detergent fiber without and corrected for ash and protein increased (P <0.05) linearly with increases of CP. But the values for digestibility of dry matter, organic matter, NFC and TDN showed quadratic effect (P <0.05) with increases of CP, with an estimated point of maximum of 65.09, 67.23, 78.35 and 67.92 at leves of 15.39, 15.22, 12.62 and 15.68% CP, respectively. The MP, without and with correction to 3.5% fat (MPC), body weight variation and composition of the milk increased linearly (P <0.05) as function of the leves of CP, except for lactose which had no effect. The efficiency of nitrogen compounds in milk (kg milk N/kg N intake) presented quadratic effect (P <0.05) estimated the minimum value of 0.21 at the level of 15.57% CP. The excretions of purine derivatives in urine and protein production, urine volume and concentration of urea in milk and blood plasma increased (P <0.05) linearly with increase the CP. However, the excretion of urea nitrogen in urine showed a quadratic effect (P <0.05), estimated minimum value of 16.27 at the level of 9.08% CP. The balance of nitrogen increased (P <0.05) linearly with the level of CP, BN is estimated to be zero in the level of 11.59% CP. The level of 14% CP in the diet is more suitable for feeding to cows with average production of 13kg/dia milk. / Avaliou-se o efeito de dietas com níveis de proteína bruta - PB (10, 12, 14 e 16% na matéria seca - MS) sobre o desempenho produtivo e eficiência de utilização dos nutrientes em vacas em lactação. Doze vacas da raça Holandesas com peso corporal (PC) médio de 570 kg, produção de leite (PL) de 13 kg/dia foram distribuídas em três quadrados latinos (4x4). O volumoso utilizado foi a silagem de milho e a relação volumoso:concentrado foi de 75:25. Houve aumento (P<0,05) linear para o consumo de todos os componentes da dieta, exceto para o consumo de carboidratos totais e carboidratos não fibrosos, que reduziram (P<0,05) linearmente com os acréscimos de PB na dieta. O consumo dos nutrientes digestíveis totais (NDT) apresentou comportamento quadrático (P<0,05) ao aumento da PB, sendo estimado o valor máximo de 10,13 kg/dia na dose de 15,62% de PB na dieta. As digestibilidades da PB, extrato etéreo, fibra em detergente neutro sem e corrigido para cinzas e proteína aumentaram (P<0,05) linearmente com os acréscimos de PB. Já os valores de digestibilidade da matéria seca, matéria orgânica, CNF e NDT apresentaram efeito quadrático (P<0,05) com os acréscimos de PB, estimando-se ponto de máximo de 65,09, 67,23, 78,35 e 67,92 nas doses de 15,39, 15,22, 12,62 e 15,68% de PB, respectivamente. A PL, sem e com correção para 3,5% de gordura (PLG), a variação de peso corporal e a composição do leite aumentaram linearmente (P<0,05) em função dos aumentos de PB, exceto para lactose que não apresentou efeito. A eficiência de utilização de compostos nitrogenados no leite (kg de N no leite/kg de N ingerido), apresentou efeito quadrático (P<0,05) estimando o valor mínimo de 0,21 no nível de 15,57% de PB. As excreções de derivados de purina na urina e produção de proteína microbiana, volume urinário e concentração de uréia no leite e no plasma sanguíneo aumentaram (P<0,05) linearmente com os aumentos de PB. No entanto, a excreção de nitrogênio uréico na urina apresentou efeito quadrático (P<0,05), estimando valor mínimo de 16,27 g/dia no nível 9,08% de PB. O balanço de nitrogênio aumentou (P<0,05) linearmente com o nível de PB, estimando-se BN nulo no nível de 11,59% de PB. O nível de 14% de PB na dieta é o mais indicado para alimentação de vacas com produção média de 13kg/dia de leite.

O projeto estrutural deve considerar as incertezas provenientes das variáveis envolvidas no dimensionamento dos elementos estruturais, tais como propriedades dos materiais, dimensões dos elementos estruturais e intensidade dos carregamentos atuantes. Existe também a variabilidade inerente aos métodos de análise estrutural, originária de imprecisões na idealização da distribuição das tensões e deformações dos elementos estruturais. Sendo assim, esta dissertação visa analisar a variabilidade dos desvios dos modelos de cálculo propostos por Blevot e Frémy (1967), Fusco (1994) e Santos (2013), todos baseados no método das bielas e tirantes, para blocos sobre duas, três e quatro estacas submetidos a carregamento centrado. Estes elementos estruturais possuem significativa importância, visto que atuam na transmissão dos esforços provenientes dos pilares às fundações profundas. Os modelos de cálculo foram confrontados entre si e com resultados experimentais de Blevot e Frémy (1967), Mautoni (1971), Clarke (1973), Miguel (2000) e Suzuki et al. (1998 / 1999 / 2000 / 2001) para determinação dos parâmetros estatísticos dos desvios desses modelos em relação aos ensaios. Os resultados apontaram desempenho satisfatório para os três modelos de cálculo. Em geral, todos os métodos se mostraram favoráveis à segurança nos casos avaliados para os três tipos de blocos de fundação. / Structural design must consider the uncertainties coming from the variables involved in dimensioning of the structural elements, such as material properties, dimensions of structural elements, and intensity of active loads. There is also inherent variability in structural analysis methods, originated from imprecision in idealization of the distribution of tensions and deformations of structural elements. Thus, this dissertation aims to analyze the variability of calculation models deviations proposed by Blevot and Frémy (1967), Fusco (1994) and Santos (2013), all based on strut and tie method, for two, three and four pile caps submitted to center load. These structural elements are of significant importance, since they act in transmission of loads from columns to deep foundations. Calculation models were compared with each other and with experimental results from Blevot and Frémy (1967), Mautoni (1971), Clarke (1973), Miguel (2000) and Suzuki et al. (1998 / 1999 / 2000 / 2001) to determine the statistical parameters of these model deviations in relation to the tests. Results indicated satisfactory performance for the three calculation models. In general, all methods were favorable to safety in cases evaluated for the three pile caps types.