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This report is a follow on of the first phase of a Federal Railroad Administration (FRA)-sponsored project to evaluate lateral ballast behavior and how mechanics-based track geometry deterioration models forecast field behavior. In Phase II of the project, Transportation Technology Center, Inc. modified the Railway Track Lifecycle Model (RTLM) by adding tamp lift height and a site?specific factor and split the model between a logarithmic settlement and a linear surface profile model. The research team also compared forecasting model projections against multiple field measurement locations at the Transportation Technology Center (TTC). The ballast settlement mechanism at most locations was ballast re-compaction and the RTLM captured the settlement behavior if only the tamp lift height parameter was used. If the settlement mechanism was degraded ballast, the logarithmic settlement curve did not capture abrupt changes in settlement rate from wetting and drying so more linear models, such as the surface profile model, should be used.

The main topic of this thesis concerns the behavior of concrete pile cap supported by four piles with two varying positions of longitudinal reinforcements. The positions include top of piles and bottom of the pile cap. For this purpose, non-linear finite element models of a pile cap are created using software ATENA 3D. The goal was to observe which position of reinforcement yields the higher bearing capacity and to observe the failure modes in the models. To achieve the above goals, a short review of theoretical background concerning shear phenomena is performed. This, in order to enhance the knowledge regarding shear stresses, shear transfer mechanism, factors affecting shear capacity, modes of shear failure and relate them to the behavior of pile cap. Furthermore, the calculation of shear resistance capacity based on Eurocode 2 using strut and tie method and sectional approach is presented. The numerical analysis started by creating four pile cap models in ATENA 3D. The difference between the models being the position and ratio of longitudinal reinforcement. The purpose behind two reinforcement ratios were to observe the behavior of pile cap model in two cases: a) when failure occurs prior to yielding of reinforcement; b) when failure occurs while reinforcement is yielding. The models are then analyzed using software ATENA Studio. The results revealed that placing the reinforcement on top of piles in case (a) increased the capacity of the model by 23.5 % and in case (b) increased the capacity by 18.5 %. This because the tensile stresses were found to be concentrated on top of piles rather than the bottom of the pile cap. The final failure mode in the model with top reinforcement position was crushing of the inclined compressive strut at the node beneath the column and in the model with bottom reinforcement position, the splitting of the compressive strut due to tensile stresses developed perpendicular to the inclined strut. The potential advantage of placing the r, Det huvudsakliga ämnet för den här avhandlingen handlar om beteendet hos pålfundament som stöds av fyra pålar med två olika positioner av längsgående armering. Positionerna inkluderar toppen av pålarna och botten av slagdynan. För detta ändamål skapas icke-linjära finita elementmodeller av en slagdyna med mjukvaran ATENA 3D. Målet var att observera vilket armeringsläge som ger den högre bärkapaciteten och att identifiera brottmekanismen i modellerna. För att uppnå ovanstående mål utförs en kort genomgång av teoretisk bakgrund rörande skjuvningsfenomen. Detta för att förbättra kunskapen om skjuvspänningar, skjuvöverföringsmekanism, faktorer som påverkar skjuvkapacitet, skjuvbrott och relaterar dem till beteendet hos slagdynan. Beräkningen av skjuvmotståndet baserad på Eurocode2 med hjälp av Srut and tie-metod och sektionsmetod. Den numeriska analysen började med att skapa fyra pålfundament i ATENA 3D. Skillnaden mellan modellerna är positionen och förhållandet mellan längsgående armering. Syftet bakom två armeringsförhållanden var att observera beteendet hos slagdynan i två fall: a) när brott inträffar innan armering plasticeras; b) när brott inträffar medan armeringen plasticeras. Modellerna analyseras sedan med hjälp av programvaran ATENA Studio. Resultaten visade att placering av armeringen ovanpå pålarna i fall a) ökade modellens kapacitet med 23,5% och i fall (b) ökade kapaciteten med 18,5%. Detta på grund av att dragspänningarna visade sig vara koncentrerade på toppen av pålarna snarare än på botten av slagdynan. Det slutliga brottet i modellen med topparmeringsposition var krossning av det lutande tryckstaget vid noden under pelaren. I modellen med bottenarmeringsposition delades kompressionsstaget på grund av dragspänningar vinkelrätt mot det lutande staget. The potential advantage of placing the reinforcement at the bottom were a better crack control and slightly less fragile failure mode compared to the top position of reinforcement. En parametrisk studie g

Předkládaná bakalářská práce se zabývá návrhem a optimalizací vybraných konstrukčních prvků těžkého montovaného skeletu vysoce zatížené skladovací haly. Podkladem pro řešení je konstrukce skutečné skladovací haly projektované v letech 2017-2018. Při návrhu prvků je kladen důraz na dosažení minimální hmotnosti konstrukce. Při této snaze u prefabrikátů často dochází ke vzniku tzv. D-oblastí. K jejich řešení jsou v bakalářské práci používány obecné metody řešení betonových konstrukcí jako metody příhradové analogie, nebo nelineární analýza metodou konečných prvků. Navržené konstrukční prvky jsou nakonec srovnány se skutečně navrženým řešením referenční skladovací haly. Součástí práce jsou statické výpočty střešní vaznice a stropního trámu/stropnice s rozpony 24 m, výkresová dokumentace haly a prefabrikátů v patřičném rozsahu, technická zpráva. K řešení bylo využito programů SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad a MS Excel., The presented thesis deals with design and optimization of selected structural elements of high-load storage hall skeleton. As a basis for the solution is taken the structure of a real storage hall designed in the years 2017-2018. The structure is designed for minimum weight. For this reason, so-called D-regions are formed on the structure. For the solution of D-areas, general methods of solution, such as STM or nonlinear FEM analyses, are used in the thesis. In the final designed structural elements are compared to the original design of the hall. Thesis include static calculation of 24 m long roof beam V1, static calculation of 24 m long ceiling beam ST1, drawing documentation and technical report. Programs were used for the calculation: SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad and MS Excel.

Předkládaná bakalářská práce se zabývá návrhem a optimalizací vybraných konstrukčních prvků těžkého montovaného skeletu vysoce zatížené skladovací haly. Podkladem pro řešení je konstrukce skutečné skladovací haly projektované v letech 2017-2018. Při návrhu prvků je kladen důraz na dosažení minimální hmotnosti konstrukce. Při této snaze u prefabrikátů často dochází ke vzniku tzv. D-oblastí. K jejich řešení jsou v bakalářské práci používány obecné metody řešení betonových konstrukcí jako metody příhradové analogie, nebo nelineární analýza metodou konečných prvků. Navržené konstrukční prvky jsou nakonec srovnány se skutečně navrženým řešením referenční skladovací haly. Součástí práce jsou statické výpočty střešní vaznice a stropního trámu/stropnice s rozpony 24 m, výkresová dokumentace haly a prefabrikátů v patřičném rozsahu, technická zpráva. K řešení bylo využito programů SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad a MS Excel., The presented thesis deals with design and optimization of selected structural elements of high-load storage hall skeleton. As a basis for the solution is taken the structure of a real storage hall designed in the years 2017-2018. The structure is designed for minimum weight. For this reason, so-called D-regions are formed on the structure. For the solution of D-areas, general methods of solution, such as STM or nonlinear FEM analyses, are used in the thesis. In the final designed structural elements are compared to the original design of the hall. Thesis include static calculation of 24 m long roof beam V1, static calculation of 24 m long ceiling beam ST1, drawing documentation and technical report. Programs were used for the calculation: SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad and MS Excel.

Předkládaná bakalářská práce se zabývá návrhem a optimalizací vybraných konstrukčních prvků těžkého montovaného skeletu vysoce zatížené skladovací haly. Podkladem pro řešení je konstrukce skutečné skladovací haly projektované v letech 2017-2018. Při návrhu prvků je kladen důraz na dosažení minimální hmotnosti konstrukce. Při této snaze u prefabrikátů často dochází ke vzniku tzv. D-oblastí. K jejich řešení jsou v bakalářské práci používány obecné metody řešení betonových konstrukcí jako metody příhradové analogie, nebo nelineární analýza metodou konečných prvků. Navržené konstrukční prvky jsou nakonec srovnány se skutečně navrženým řešením referenční skladovací haly. Součástí práce jsou statické výpočty střešní vaznice a stropního trámu/stropnice s rozpony 24 m, výkresová dokumentace haly a prefabrikátů v patřičném rozsahu, technická zpráva. K řešení bylo využito programů SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad a MS Excel., The presented thesis deals with design and optimization of selected structural elements of high-load storage hall skeleton. As a basis for the solution is taken the structure of a real storage hall designed in the years 2017-2018. The structure is designed for minimum weight. For this reason, so-called D-regions are formed on the structure. For the solution of D-areas, general methods of solution, such as STM or nonlinear FEM analyses, are used in the thesis. In the final designed structural elements are compared to the original design of the hall. Thesis include static calculation of 24 m long roof beam V1, static calculation of 24 m long ceiling beam ST1, drawing documentation and technical report. Programs were used for the calculation: SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad and MS Excel.

Předkládaná bakalářská práce se zabývá návrhem a optimalizací vybraných konstrukčních prvků těžkého montovaného skeletu vysoce zatížené skladovací haly. Podkladem pro řešení je konstrukce skutečné skladovací haly projektované v letech 2017-2018. Při návrhu prvků je kladen důraz na dosažení minimální hmotnosti konstrukce. Při této snaze u prefabrikátů často dochází ke vzniku tzv. D-oblastí. K jejich řešení jsou v bakalářské práci používány obecné metody řešení betonových konstrukcí jako metody příhradové analogie, nebo nelineární analýza metodou konečných prvků. Navržené konstrukční prvky jsou nakonec srovnány se skutečně navrženým řešením referenční skladovací haly. Součástí práce jsou statické výpočty střešní vaznice a stropního trámu/stropnice s rozpony 24 m, výkresová dokumentace haly a prefabrikátů v patřičném rozsahu, technická zpráva. K řešení bylo využito programů SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad a MS Excel., The presented thesis deals with design and optimization of selected structural elements of high-load storage hall skeleton. As a basis for the solution is taken the structure of a real storage hall designed in the years 2017-2018. The structure is designed for minimum weight. For this reason, so-called D-regions are formed on the structure. For the solution of D-areas, general methods of solution, such as STM or nonlinear FEM analyses, are used in the thesis. In the final designed structural elements are compared to the original design of the hall. Thesis include static calculation of 24 m long roof beam V1, static calculation of 24 m long ceiling beam ST1, drawing documentation and technical report. Programs were used for the calculation: SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad and MS Excel.

Předkládaná bakalářská práce se zabývá návrhem a optimalizací vybraných konstrukčních prvků těžkého montovaného skeletu vysoce zatížené skladovací haly. Podkladem pro řešení je konstrukce skutečné skladovací haly projektované v letech 2017-2018. Při návrhu prvků je kladen důraz na dosažení minimální hmotnosti konstrukce. Při této snaze u prefabrikátů často dochází ke vzniku tzv. D-oblastí. K jejich řešení jsou v bakalářské práci používány obecné metody řešení betonových konstrukcí jako metody příhradové analogie, nebo nelineární analýza metodou konečných prvků. Navržené konstrukční prvky jsou nakonec srovnány se skutečně navrženým řešením referenční skladovací haly. Součástí práce jsou statické výpočty střešní vaznice a stropního trámu/stropnice s rozpony 24 m, výkresová dokumentace haly a prefabrikátů v patřičném rozsahu, technická zpráva. K řešení bylo využito programů SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad a MS Excel., The presented thesis deals with design and optimization of selected structural elements of high-load storage hall skeleton. As a basis for the solution is taken the structure of a real storage hall designed in the years 2017-2018. The structure is designed for minimum weight. For this reason, so-called D-regions are formed on the structure. For the solution of D-areas, general methods of solution, such as STM or nonlinear FEM analyses, are used in the thesis. In the final designed structural elements are compared to the original design of the hall. Thesis include static calculation of 24 m long roof beam V1, static calculation of 24 m long ceiling beam ST1, drawing documentation and technical report. Programs were used for the calculation: SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad and MS Excel.

Předkládaná bakalářská práce se zabývá návrhem a optimalizací vybraných konstrukčních prvků těžkého montovaného skeletu vysoce zatížené skladovací haly. Podkladem pro řešení je konstrukce skutečné skladovací haly projektované v letech 2017-2018. Při návrhu prvků je kladen důraz na dosažení minimální hmotnosti konstrukce. Při této snaze u prefabrikátů často dochází ke vzniku tzv. D-oblastí. K jejich řešení jsou v bakalářské práci používány obecné metody řešení betonových konstrukcí jako metody příhradové analogie, nebo nelineární analýza metodou konečných prvků. Navržené konstrukční prvky jsou nakonec srovnány se skutečně navrženým řešením referenční skladovací haly. Součástí práce jsou statické výpočty střešní vaznice a stropního trámu/stropnice s rozpony 24 m, výkresová dokumentace haly a prefabrikátů v patřičném rozsahu, technická zpráva. K řešení bylo využito programů SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad a MS Excel., The presented thesis deals with design and optimization of selected structural elements of high-load storage hall skeleton. As a basis for the solution is taken the structure of a real storage hall designed in the years 2017-2018. The structure is designed for minimum weight. For this reason, so-called D-regions are formed on the structure. For the solution of D-areas, general methods of solution, such as STM or nonlinear FEM analyses, are used in the thesis. In the final designed structural elements are compared to the original design of the hall. Thesis include static calculation of 24 m long roof beam V1, static calculation of 24 m long ceiling beam ST1, drawing documentation and technical report. Programs were used for the calculation: SCIA Engeneer 18.1, Idea StatiCa Beam10.1, Idea StatiCa Detail 10.1, RIB Fermo, PTC MathCad and MS Excel.

0-7039, The strut-and-tie method (STM) is a reliable and widely used approach for designing reinforced concrete members, but there are still gaps in knowledge that need to be addressed to optimize its use in common design scenarios. Addressing these gaps would lead to more efficient and cost-effective design solutions. This requires additional experimental data to inform design codes and practices related to key areas, such as tri-axial tension anchorage, curved-bar nodes, confining reinforcement in nodal zones, and crack control reinforcement spacing. Chapters 3-6 of the research report describe the experimental investigations conducted to address some of these knowledge gaps. Chapter 3 presents insights into the behavior of drilled shaft reinforcement under tri-axial tension and the validity of the design recommendation. Chapter 4 investigates the effect of the bend radius on the behavior of closing knee joints and recommends an equation for designing curved-bar nodes. Chapter 5 examines the effect of nodal zone confinement on nodal strength, concluding that effective confining reinforcement can increase nodal strength. Lastly, Chapter 6 investigates the possibility of relaxing crack control reinforcement spacing and recommends a new maximum spacing. Overall, the research findings provide valuable insights into the behavior of reinforced concrete members and suggest improvements for STM design practices.

0-7039, The strut-and-tie method (STM) is a simple and widely used method for designing D-regions in reinforced concrete members. Despite its incorporation into major design codes and continuous refinement over the past century, there are still areas that require further research. These include the use of 3D strut- and-tie models for designing drill shaft footings under eccentric axial loads, the use of curved- bar nodes in closing knee joints, the provision of appropriate confinement to enhance nodal strength, and the relaxation of the “d/4 limit” on crack control reinforcement spacing based on experimental data. Addressing these knowledge gaps would improve the applicability and cost- effectiveness of STM in reinforced concrete deep member design.

DTFR5311D00008L, This report compiles the first phase of a Federal Railroad Administration (FRA)-sponsored project to evaluate lateral ballast behavior and how mechanics-based track geometry deterioration models forecast field behavior. The lateral ballast behavior section analyzed historical and recent single tie push test (STPT) results, compared the influence various ballast parameters, and evaluated the potential ability of a model to estimate lateral track strength from outputs of track inspection vehicles. The results suggest that a track location could eventually be placed into broad risk categories based on the measurable ballast condition. The second aspect investigated the ability of mechanics-based track geometry deterioration models to forecast field behavior. Field data that included aligned track geometry records and ground penetrating radar (GPR) was analyzed and relationships were developed between the ballast condition and track geometry deterioration rate. The existing mechanics-based models were compared against the statistically fit models and recommendations on how to improve the models were made.

Research Study 0-1302, At congested highway interchanges, the Texas Department of Transportation (TxDOT) uses narrow concrete piers and, shallow depth steel cap girders. Research Project ()"1302 is concerned with the connection detail between these two, elements. This report deals with the shear strength and reinforcement details at the top of the concrete pier in the vicinity of, the bearings. Since no formal design procedure currently exists for determining the required amount and distribution of, reinforcing steel in a pier cap, this research also had the purpose of providing design guidelines for the pier cap. To, in'vestigate the behavior of the pier caps, six test specimens were constructed at a 30% scale. Five different reinforcing steel, patterns were used in the six specimens to examine the contributions of different reinforcing types to the pier cap strength., Eleven static load tests were conducted to failure on the six pier caps. For all specimens, load on the pier cap was, carried primarily by the action of a tied arch which transferred load from the base plates into the column. Overall, specimens that had a greater quantity of horizontal reinforcing steel and adequate development of horizontal reinforcing had, a greater capacity., Three design methods were used to analyze the strength of the pier caps tested: (1) AASHTO (1992) Corbel Provisions, (2)ACI 318-89 Deep Beam Provisions; and (3) Strut-and-TIeMethod. The corbel and deep beam provisions were very, conservative in predicting the capacity of the pier cap because they consider only concrete capacity in shear. On average, these two methods underestimated the pier strength by a factor of 3 to 4. Testing showed that the pier cap resisted loads, through a tied arch, which is a much stronger load-carrying mechanism than concrete in shear. The strut-and-tie models, used were much more accurate than conventional design methods in predicting the capacity of the pier caps because they, model the compression arch action observed during testing. The strut-and-tie method is suggested for design because, strut-and-tie analyses gave the best correlation with test results, modeled true behavior, and were still conservative., To detail the use of the strut-and-tie method, a design example using a proposed strut-and-tie model is presented. Also, recommendations are given for evaluating existing pier caps through field inspection.

Precast/prestressed concrete girders are commonly used in bridge construction in the United States. The application and diffusion of the prestress force in a pretensioned girder cause a vertical tension force to develop near the end of the beam. Field surveys of the beam ends of pretensioned bridge girders indicate that many of the precast bulb-T (PCBT) beams used in Virginia develop cracks within the anchorage zone region. The lengths and widths of these cracks range from acceptable to poor and in need of repair. Field observations also indicate deeper cross sections, very heavily prestressed sections, and girders with lightweight concrete tend to be most susceptible to crack formation. This research examined a new strut-and-tie based design approach to the anchorage zone design of the PCBT bridge girders used in Virginia. Case study girders surveyed during site visits were used to illustrate the nature of the problem and support the calibration of the strut-and-tie-based model. A parametric study was conducted using this proposed design model, and the results of this study were consolidated into anchorage zone design tables. The results of the parametric study were compared to the results obtained using existing anchorage zone design models, international bridge codes, and standard anchorage zone details used by other states. A set of new standard details was developed for the PCBT girders that incorporates elements of the new design approach and is compatible with the anchorage zone design aids. A 65-ft PCBT-53 girder was fabricated offsite and tested at the Virginia Tech Structures Lab to verify the new strut-and-tie-based design model. This girder contained anchorage zone details designed with the new model. The new anchorage zone details were successful at controlling the development of anchorage zone cracks. The new design approach is recommended for implementation by the Virginia Department of Transportation.

Research Study 0-1364, In designing large cantilever bent caps for use on recent projects under current AASHTO design specifications, designers were faced with considerable uncertainties. Questions arose when designers attempted to satisfy, both serviceability and strength requirements for a series of cap designs that mixed both non-prestressed and, prestressed concrete solutions. The problems were complicated because of uncertainty whether AASHTO, corbel or deep beam provisions would apply. The resulting designs were highly congested, had poor, constructibility and high costs., This report outlines development of a new design approach involving use of strut-and-tie models (STM), as, well as a mix of prestressed and non-prestressed main flexural reinforcement. A series of sixteen bent cap, overhangs were designed, built at a reduced scale, and loaded to failure. Deflections, crack patterns and, widths, reinforcement strains, and overall behavior were observed. Economic and constructibility issues were, examined. The use ofT-headed anchorages was explored., A comprehensive design approach that considers both serviceability issues (deflections, cracking, crack, widths, fatigue stress ranges, and side face crack control) and strength issues (ductility, adequacy of STM, design and analysis of flexural capacity} was developed. Recommendations for design and detailing to, improve behavior, reduce congestion and improve constructibility are provided.

Project 0-5997, The effects of ASR/DEF on the D-regions of structures are investigated by means of a dual experimental and, analytical modeling program. Four near full scale specimens that represent cantilever and straddle pier bents, that are representative of typical bridges in Texas, are constructed, conditioned over time, and tested to failure., The undamaged first specimen serves as the control specimen, while the next two are tested after eight months, and two years of field conditioning through the Texas heat along with supplemental water aimed at promoting, ASR/DEF. The fourth remains to be tested within the next three years. In the two specimens subjected to, deterioration, early formation of ASR gel is observed, and with time load-induced cracks along with other, additional cracks are observed. These additional cracks are a result of the continued formation of ASR gel, which causes the concrete to swell, and in turn puts the reinforcing steel into a state of active prestress. It is, observed that the failure mechanism in all the specimens is a brittle shear failure through the beam-column, joint. Specimens with ASR/DEF deterioration show greater stiffness and strength, and slightly greater ductility., A Compatibility Strut-and-Tie (C-STM) technique is developed as a suitable minimalist analysis technique to, model the force-deformation behavior of reinforced concrete bridge piers with significant D-regions that may, be deteriorated through ASR/DEF effects. The C-STM simulates the overall and the internal behavior of the, structure very well. In spite of the disturbing appearances of the ASR/DEF damage arising from concrete, swelling and cracking, the performance and strength of the specimens are not impaired. Damage that appears in, the cover concrete region is offset by the mild level of confinement to the core concrete induced by the, reinforcing steel.

Project 0-5997, When a bridge engineer encounters a design or analysis problem concerning a bridge substructure, that structure will commonly have a mixture of member types, some slender, and some squat. Slender members are generally governed by flexure, and normal beam theory should suffice for analysis and design. Squat members can often be handled by beam theory too, although nowadays designers have a choice and may opt to use strut-and-tie (SAT) models.