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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Semi-Quantitative Assessment Framework for Corrosion Damaged Slab-on-Girder Bridge Columns Using Simplified Nonlinear Finite Element Analysis

Mohammed, Amina January 2014 (has links)
Most of existing North American bridge infrastructure is reported to be deficient. Present infrastructure management mainly relies on qualitative evaluation, where bridge safety and serviceability are judged through routine visual inspection. With the successive increase in the number of severely deficient bridges and the limited available resources, it is crucial to develop a performance-based quantitative assessment evaluation approach that enables an accurate estimation of aging bridges ultimate and seismic capacities and ensures their serviceability. Reinforcement corrosion is the main cause of most of North American concrete infrastructure deterioration. Experimental investigations prove that reinforcement corrosion results in reduction of the steel reinforcement cross sectional area, localized (or global in very extreme cases) loss of bond action, concrete spalling, loss of core concrete confinement, and structural collapse. Field observations show that damage due to reinforcement corrosion in reinforced concrete (RC) bridge columns is localized in highly affected zones by splash of deicing water. In this thesis, an innovative performance-based semi-quantitative assessment framework is developed using newly developed simplified nonlinear static and dynamic finite element analysis approaches. The framework integrates the bridge’s available design and after-construction information with enhanced inspection and additional material testing as sources for accurate input data. In order to evaluate the structural performance and the capacity of the corrosion-damaged bridge columns, four nonlinear static and dynamic analysis approaches have been developed: (i) simplified nonlinear sectional analysis (NLSA) approach that presents the basis of the analysis approaches to estimate the ultimate and seismic capacities, and serviceability of bridge columns; (ii) simplified nonlinear finite element analysis (NLFEA) approach, which enables estimating the ultimate structural capacity of corrosion-damaged RC columns; (iii) simplified hybrid linear/nonlinear dynamic finite element analysis (SHDFEA) approach to evaluate the serviceability of the bridge; and, (iv) simplified non-linear seismic analysis (SNLSA) approach to evaluate the seismic capacity of the bridge columns. The four analysis approaches are verified by comprehensive comparisons with available test experimental and analytical results. The proposed semi-quantitative assessment framework suggests three thresholds for each performance measure of the evaluation limit states to be decided by the bridge management system team. Case studies are presented to show the integrity and the consistency of using the proposed assessment framework. The proposed assessment framework together with the analysis approaches provide bridge owners, practicing engineers, and management teams with simplified and accurate evaluation tools, which lead to reduce the maintenance/rehabilitation cost and provide better safety, and reduce the variation in the data collected using only traditional inspection methods.
92

Field and Analytical Studies of the First Folded Plate Girder Bridge

Sit, Man Hou 29 August 2014 (has links)
Integral abutment bridges are very common for short span bridges in the United State due to their less construction and maintenance cost and generally good performance. This thesis studies the first integral abutment bridge using Folded Plate Girder (FPG) Bridge System. The bridge is instrumented with a variety of gauges to capture the behavior of the bridge, and a total of two year and one month [11/2011~12/2013] of data are collected and long-term data monitoring is performed. Live load test and long term temperature effect on the bridge are studied using finite element modeling and compared with actual field data. Girder strain/stress at mid-span and quarter-span and abutment rotations were investigated. From the result, first the bridge was found to show good performance. Shear lag effect was found to be happening at the bottom flange-to-web junction of the steel girder when subjected to concentrated loading. Thermal gradient was found to be significant on the girder strain and abutment rotations.
93

LIVE LOAD DISTRIBUTION FACTORS FOR HORIZONTALLY CURVED CONCRETE BOX GIRDER BRIDGES

Zaki, Mohammed 07 November 2016 (has links)
Live load distribution factors are used to determine the live-load moment for bridge girder design when a two dimensional analysis is conducted. A simple, analysis of bridge superstructures are considered to determine live-load factors that can be used to analyze different types of bridges. The distribution of the live load factors distributes the effect of loads transversely across the width of the bridge superstructure by proportioning the design lanes to individual girders through the distribution factors. This research study consists of the determination of live load distribution factors (LLDFs) in both interior and exterior girders for horizontally curved concrete box girder bridges that have central angles, with one span exceeding 34 degrees. This study has been done based on real geometry of bridges designed by a company for different locations. The goal of using real geometry is to achieve more realistic, accurate, and practical results. Also, in this study, 3-D modeling analyses for different span lengths (80, 90, 100, 115, 120, and 140 ft) have been first conducted for straight bridges, and then the results compared with AASHTO LRFD, 2012 equations. The point of starting with straight bridges analyses is to get an indication and conception about the LLDF obtained from AASHTO LRFD formulas, 2012 to those obtained from finite element analyses for this type of bridge (Concrete Box Girder). After that, the analyses have been done for curved bridges having central angles with one span exceeding 34 degrees. Theses analyses conducted for various span lengths that had already been used for straight bridges (80, 90, 100, 115, 120, and 140 ft) with different central angles (5º, 38º, 45º, 50º, 55º, and 60º). The results of modeling and analyses for straight bridges indicate that the current AASHTO LRFD formulas for box-girder bridges provide a conservative estimate of the design bending moment. For curved bridges, it was observed from a refined analysis that the distribution factor increases as the central angle increases and the current AASHTO LRFD formula is applicable until a central angle of 38º which is a little out of the LRFD`s limits.
94

Most přes řeku Berounku / Bridge over the Berounka river

Gratza, Jonáš January 2018 (has links)
Diploma thesis is focused on a design of the road bridge in Roztoky municipality. The bridge spans Berounka river. The design is processed in three options and the selected option was developed in greater detail. The layout of bridge is designed as a girder box with haunch. The bridge will be built by a cantilever erection method. Structural analysis of the bridge regards the influences of construction by TDA method. The structure is assessed for temporary and permanent states. The assessment of the structure was made according to EC.
95

Ocelová konstrukce hangáru / Steel construction of a hangar

Plačková, Markéta January 2018 (has links)
This Master´s thesis describes the design and assessment of steel structure of a hangar located in Znojmo. The supporting structure of a hangar is 37,475 m span, 48 m lenght, clear hight at the highest point is 15,5 m. Main construction material is steel, grade S355J2. The supporting structure consist of a truss girders. The distance of each cross link sis 4 m. There is prepared statics calculation of the main load-bearing parts of the structure, including joints and details. The valid standards CSN EN were used in processing of this dissertation.
96

Ocelová konstrukce skleníku v botanické zahradě / Steel structure of greenhouse in botanical garden

Brodová, Kateřina January 2019 (has links)
The aim of the diploma thesis is design and assessment of steel structure of greenhouse in botanical garden in Ostrava. The building is designed as a hexagon with a diameter 50 m, the highest point of the construction is 32,907 m. Whole structure will be made of hollow round tubes of different profiles. The support system consist of columns and truss girders. The bracing of the structure is in three levels. Main construction material is steel S355 J0+AR. The covering of the roofs and walls is made of glass panels ISOTHERM.
97

Administrativní budova / Administrative building

Polerecká, Katarína January 2019 (has links)
The aim of this thesis is design and assessment of the steel structure of the multi-storey administration center in Martin. Floor plan dimensions are in the shape of a square 40 x 40 m. Column spacing is 8mx8x. Building has 6 floors and total height is 22,2m. Floor and roof structure is made of steel-concrete composite slab . Part of the work is analyze two different versions. Version A has longitudinal rigidity due to truss bracing. Rigidity of Version B has is ensured by frame conections between beams and columns.Version A was selected as better solution. All parts, except truss braicing is made of rolled beams. The whole structure is made of steel S355.
98

Rekonstrukce stávajícího mostu / Reconstruction of the existing bridge structure

Biller, Martin January 2013 (has links)
Master's thesis deals with the reinforcement and expansion of girder bridge (continuous bridge with three spans) across the river Jihlava in Ivančice and reinforcement on the load class A. This is done by using an additional external prestressing cables and composite monolithic slab. Amplification is verified by calculation of load capacity.
99

Most přes dálnici / Bridge over a highway

Vaculíková, Klára January 2015 (has links)
The diploma thesis describes the design of curved, pre-stressed concrete bridge over the highway D1. A variant, that is chosen for detail analysis, is a spine girder construction as a continuous beam with 3 spans. The thesis solves the construction to limit states according to applicable European standards (Eurocodes). There are developed clear and detailed drawings and visualization of the bridge.
100

Most na silnici I/38 v Jihlavě / Bridge on the I/38 road in Jihlava

Němec, Martin January 2017 (has links)
Diploma thesis is focused on design of road bridge bearing structure over road in Jihlava. The construction is girder with 3 fields beard by local supports. Calculations were made in the program called Scia Engineer. Appraisals were made by hand.

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