Dissertations / Theses on the topic 'Steel girder structural tests'

This thesis describes the experimental appraisal of a series of 10 'non-sway' steel column subassemblages, each comprising a 6m long column with up to three 1.5m long beams, together with two full-scale 3 storey, 2 bay, single span, non-sway steel frames (typical overall dimensions 9m x 10m x 3.5m). The subassemblages tests were conducted in the Department of Civil and Structural Engineering at the University of Sheffield whilst the much larger frame tests were carried out at the Building Research Establishment. In all cases, the beam and column elements were connected using 'simple' bolted steelwork connections. The aim was to investigate the effect of the inherent rotational stiffness (semi-rigid characteristics) of such connections on the behaviour of steel frames in which the columns were loaded biaxially and were not restricted to in-plane deformation. The appraisal of the results from these experiments clearly shows that the stiffness of even the most modest connection can have a significant influence on the distribution of bending moments, the ultimate column capacity and deflection of frame members. The experimental data were subsequently used to validate the predictions of a sophisticated finite-element computer program which was developed specifically to analyse 3-dimensional column subassemblages employing semi-rigid connections. This thesis documents this validation and reports the findings of an extensive parametric study which was then conducted to investigate the influence of semi-rigid connection behaviour on a wide range of subassemblage configurations. Comparisons with the experimentally observed and analytically predicted ultimate capacities of the subassemblage and frame tests showed that 'commonly used' methods of frame design are unduly conservative. The author has therefore proposed a number of design approaches for both ultimate and serviceability limit state loading conditions which take into account the inherent benefits of semi-rigid joint action.

The scheduled replacement of the 8th North Bridge, in Salt Lake City, UT, presented a unique opportunity to test a pre-cast concrete deck, steel girder bridge. A live-load test was performed under the directions of Bridge Diagnostic Inc (BDI) and Utah State University. Six different load paths were chosen to be tested. The recorded data was used to calibrate a finite-element model of this superstructure, which was created using solid, shell, and frame elements. A comparison between the measured and finite-element response was performed and it was determined that the finite-element model replicated the measured results within 3.5% of the actual values. This model was later used to obtain theoretical live-load distribution factors, which were compared with the AASHTO LRFD Specifications estimations. The analysis was performed for the actual condition of the bridge and the original case of the bridge, which included sidewalks on both sides. The comparison showed that the code over predicted the behavior of the actual structure by 10%. For the original case, the code's estimation differed by as much as 45% of the theoretical values. Another opportunity was presented to test the behavior of a cast-in-place concrete box girder bridge in Joaquin County, CA. The Walnut Grove Bridge was tested by BDI at the request of Utah State University. The test was performed with six different load paths and the recorded data was used to calibrate a finite-element model of the structure. The bridge was modeled using shell elements and the supports were modeled using solid elements. The model was shown to replicate the actual behavior of the bridge to within 3% of the measured values. The calibrated model was then used to calculate the theoretical live-load distribution factors, which allowed a comparison of the results with the AASHTOO LRFD Specifications equations. This analysis was performed for the real conditions of the bridge and a second case where intermediate diaphragms were not included. It was determined that the code's equations estimated the behavior of the interior girder more accurately for the second model (within 10%) than the real model of the bridge (within 20%).

The effects of support in steel bridges can present significant challenges during the construction. The tendency of girders to twist or layovers during the construction can present a particularly challenging problem regarding detailing cross-frames that provide bracing to steel girders. Methods of detailing cross-frames have been investigated in the past to identify some of the issues related to the behavior of straight and skewed steel bridges. However, the absence of a complete and simplified design approach has led to disputes between stakeholders, costly repairs and delays in the construction. The main objective of this research is to develop a complete and simplified design approach considering construction, fabrication and detailing of skewed bridges. This objective is achieved by comparing different detailing methods, understanding the mechanism by which skew effects develop in steel bridges, recommending simplified methods of analysis to evaluate them, and developing a complete and simplified design procedure for skew bridges. Girder layovers, flange lateral bending stress, cross-frame forces, component of vertical deflections, component of vertical reactions and lateral reactions or lateral displacements are affected by detailing methods and are referred as lack-of-fit effects. The main conclusion of this research is that lack-of-fit effects for the Final Fit detailing method at the steel dead load stage are equal and opposite to the lack-of-fit effects for the Erected Fit detailing method at the total dead load stage. This conclusion has helped using 2D grid analyses for estimating these lack-of-fit effects for different detailing methods. 3D erection simulations are developed for estimating fit-up forces required to attach the cross-frames to girders. The maximum fit-up force estimated from the 2D grid analysis shows a reasonable agreement with the one obtained from the erection simulations. The erection sequence that reduces the maximum fit-up force is also found by erection simulations. The line girder analysis is recommended for calculating cambers for the Final Fit detailing method. A combination of line girder analysis and 2D grid analysis is recommended for calculating cambers for the Erected Fit detailing method. Finally, flowcharts are developed that facilitate the selection of a detailing method and show the necessary design checks.

The research was focused on the three major structural elements of a typical cold-formed steel building - shear wall, floor joist, and column. Part 1 of the thesis explored wider options in the steel sheet sheathing for shear walls. An experimental research was conducted on 0.030 in and 0.033 in. (2:1 and 4:1 aspect ratios) and 0.027 in. (2:1 aspect ratio) steel sheet shear walls and the results provided nominal shear strengths for the American Iron and Steel Institute Lateral Design Standard. Part 2 of this thesis optimized the web hole profile for a new generation C-joist, and the web crippling strength was analyzed by finite element analysis. The results indicated an average 43% increase of web crippling strength for the new C-joist compared to the normal C-joist without web hole. To improve the structural efficiency of a cold-formed steel column, a new generation sigma (NGS) shaped column section was developed in Part 3 of this thesis. The geometry of NGS was optimized by the elastic and inelastic analysis using finite strip and finite element analysis. The results showed an average increment in axial compression strength for a single NGS section over a C-section was 117% for a 2 ft. long section and 135% for an 8 ft. long section; and for a double NGS section over a C-section was 75% for a 2 ft. long section and 103% for an 8 ft. long section.

The mechanism of metal material failure due to inelastic cyclic deformations is commonly described as Low-Cycle Fatigue (LCF). Fracture in steel structures caused by earthquakes can be associated with this mechanism. Mathematical expressions describing the material deterioration due to LCF are often referred to as LCF laws. The accurate determination of the safety of steel structures against earthquake-induced failure requires the use of LCF laws which have been sufficiently validated with experimental test data. The present study combined experimental testing and computational simulation to enhance the understanding of structural steel fracture due to LCF. The experiments were conducted in specimens extracted from the flat and corner regions of two rectangular steel hollow sections with different thickness. A total of 60 cylindrical specimens with a circumferential notch were subjected to different combinations of axial and torsional loading. The loading protocols and notch geometry were designed to produce different stress states at the location of fracture initiation. Finite element analyses were conducted to obtain the stress state and inelastic strains at the fracture initiation location. This information was then used for the calibration of five existing LCF laws. The calibration also allowed the comparative evaluation of the capability of the different laws to capture fracture initiation for different stress states, with a single set of values for the various parameters. The accuracy of the calibrated LCF laws to predict fracture initiation in a large-scale test was also investigated. To this end, a test was conducted on a rectangular steel tube subjected to cyclic axial loading. A finite element analysis of this test was conducted, and predictions of the instant and location of fracture initiation using the calibrated LCF laws were compared with the experimental observations.
Doctor of Philosophy
The mechanism of material failure due to repeated cycles of large deformations is denoted as Low-Cycle Fatigue (LCF); this failure mechanism can occur in steel structures subjected to loading conditions such as those induced by earthquakes. Mathematical expressions that evaluate the material deterioration due to LCF are often used to predict the instant and location of fracture initiation in small-scale and large-scale tests. An experimental program was conducted for the study of fracture associated with LCF. A total of 60 specimens were fabricated with material extracted from the flat and corner regions of two rectangular steel tubes; the applied loads elongated and/or twisted the specimens until they ruptured. Computational simulations of these tests were conducted to obtain key information at the location of the observed fracture initiation. This information was used to adjust five mathematical expressions suggested by previous researchers that could predict the same instant of fracture initiation observed in the experiments. The accuracy of the predictions from each of these mathematical expressions was evaluated. The accuracy of these mathematical expressions to predict fracture initiation in a large-scale test was also investigated. To this end, an experiment was conducted on a rectangular steel tube subjected to repeated cycles of deformation. A computational simulation of this test was also developed, and predictions of the instant and location of fracture initiation were compared with the experimental observations.

This research investigates the strength behavior of horizontally curved composite I-girder bridge structural systems, and the representation of this behavior by the AASHTO (2004b) LRFD provisions. The primary focus is on the design of a representative curved composite I-girder bridge tested at the FHWA Turner-Fairbank Highway Research Center, interpretation of the results from the testing of this bridge, including correlation with extensive linear and nonlinear finite element analysis solutions, and parametric extension of the test results using finite element models similar to those validated against the physical tests. These studies support the potential liberalization of the AASHTO (2004b) provisions by the use of a plastic moment based resistance, reduced by flange lateral bending effects, for composite I-girders in positive bending.

The construction of horizontally curved bridges with skewed supports requires careful consideration. These types of bridges exhibit three-dimensional response characteristics that are not commonly seen in straight bridges with normal supports. As a result, engineers may face difficulties during the construction, when the components of the bridge do not fit together or the final geometry of the structure does not correspond to that intended by the designer. These complications can lead to problems that compromise the serviceability aspects of the bridge and in some cases, its structural integrity. The three dimensional response that curved and skewed bridges exhibit is directly influenced by the bracing system used to configure the structure. In I-girder bridges, cross-frames are provided to integrate the structure, transforming the individual girders into a structural system that can support larger loads than when the girders work separately. In general, they facilitate the construction of the structure. However, they can also induce undesired collateral effects that can be a detriment to the performance of the system. These effects must be considered in the design of a curved and skewed bridge because, in some cases, they can modify substantially its response. This research is focused on understanding how the bracing system affects the performance of curved and skewed I-girder bridges, as well as, the ability of the approximate analysis methods to capture the structural behavior. In this research, techniques that can be implemented in the creation of 2D-grid models are developed to overcome the limitations of this analysis method. In addition, efficient cross-frame arrangements that mitigate the collateral effects of skew are developed. These mitigation schemes reduce the undesired cross-frame forces and flange lateral bending stresses associated with the transverse stiffness of the structure, while ensuring that the bracing system still performs its intended functions.

Curved and skewed I-girder bridges exhibit torsional displacements of the individual girders and of the overall bridge cross-section under dead loads. As a result, the girder webs can be plumb in only one configuration. If the structure is built such that the webs are plumb in the ideal no-load position, they generally cannot be plumb under the action of the structure's steel or total dead load; hence, twisting of the girders is unavoidable under dead loads. The deflected geometry resulting from these torsional displacements can impact the fit-up of the members, the erection requirements (crane positions and capacities, the number of temporary supports, tie down requirements, etc.), the bearing cost and type, and the overall strength of the structure. Furthermore, significant layover may be visually objectionable, particularly at piers and abutments. If the torsional deflections are large enough, then the cross-frames are typically detailed to compensate for them, either partially or fully. As specified in Article C6.7.2 of the AASHTO LRFD Specifications, different types of cross-frame detailing methods are used to achieve theoretically plumb webs under the no-load, steel dead load, or total dead load conditions. Each of the cross-frame detailing methods has ramifications on the behavior and constructability of a bridge. Currently, there is much confusion and divergence of opinion in the bridge industry regarding the stage at which steel I girder webs should be ideally plumb and the consequences of out-of-plumbness at other stages. Furthermore, concerns are often raised about potential fit-up problems during steel erection as well as the control of the final deck geometry (e.g., cross-slopes and joint alignment). These influences and ramifications of cross-frame detailing need to be investigated and explained so that resulting field problems leading to needless construction delays and legal claims can be avoided. This dissertation addresses the influence of cross-frame detailing on curved and/or skewed steel I girder bridges during steel erection and concrete deck placement by conducting comprehensive analytical studies. Procedures to determine the lack-of-fit forces due to dead load fit (DLF) detailing are developed to assess the impact of different types of cross-frame detailing. The studies include benchmarking of refined analytical models against selected full scale experimental tests and field measurements. These analytical models are then utilized to study a variety of practical combinations and permutations of bridge parameters pertaining to horizontal curvature and skew effects. This research develops and clarifies procedures and provides new knowledge with respect to the impact of cross-frame detailing methods on: 1) constructed bridge geometries, 2) cross-frame forces, 3) girder stresses, 4) system strengths, 5) potential uplift at bearings, and 6) fit-up during erection. These developments provide the basis for the development of refined guidelines for: 1) practices to alleviate fit-up difficulties during erection, 2) selection of cross-frame detailing methods as a function of I-girder bridge geometry characteristics, and 3) procedures to calculate the locked-in forces due to DLF cross-frame detailing.

A number of recent fires in single-storey warehouses have drawn attention to a current lack of understanding about the structural response of industrial portal frame structures to elevated temperatures. This research project has investigated the subject by conducting fire tests on a scaled model and by computer modelling using the non-linear finite element program VULCAN. This program has been developed in-house by the University of Sheffield and is capable of modelling the behaviour of three-dimensional steel and composite frames at elevated temperatures. It has been validated throughout its development. An initial investigation was conducted to validate the program for analysing inclined members, which form part of a pitched- roof portal frame, but for which it was not initially developed. Additional features were implemented into the program where necessary. A series of indicative fire tests was conducted at the Health and Safety Laboratories, Buxton. A scaled portal frame model was designed and built, and three major fire tests were conducted in this structure. In the third of these tests the heated rafters experienced a snap-through failure mechanism, in which fire hinges could clearly be identified. The experimental results were then used for validating the numerical results produced by VULCAN analyses. The correlations were relatively close, both for predictions of displacements and failure temperatures. This gave increased confidence in using VULCAN to conduct a series of parametric studies. The parametric studies included two- and three-dimensional analyses, and a number of parameters were investigated, including the effects of vertical and horizontal load, frame geometry, heating profiles and base rotational stiffness. The influence of secondary members was investigated in the three-dimensional studies using different fire scenarios. A simplified calculation method has been developed for estimating the critical temperatures of portal frames in fire. The results compare well with predictions from VULCAN. The current guidance document for portal frames in boundary conditions has been reviewed, and the concept of performance-based design for portal frame structures has been discussed.

Thesis (M.S.) -- Worcester Polytechnic Institute.
Keywords: Office buildings; Steel beams; Lumped parameter method; Cardington Tests; Design fire curves . Includes bibliographical references (leaves 144-146).

The goal of Master´s thesis is design and assessment of the swimming pool hall in Ostrava. Tha hall has two parts – swimming pool and other places for facility and free time activities.The hall has rectangle plan of dimension 30x47,4 and 15x45m. Three construction will be design. The steel truss girder wil be elaborate.

Diploma thesis describes the design and assessment of the roof structure that covers the courtyard of office buildings. Structure has a regular floor plan and roof height is 15,0 m. The material if the structure is steel S355, bolts 8.8., steel of the pins is S355. Construction is located in Brno. Two options were produced and designed, evaluated according to the latest standards.

The aim of the master thesis was a design of the steel-concrete composite road bridge for a main road in Ostrava. The part of the design was a variant design of the bridge which has theoretical spans equal to 44 m + 55 m + 44 m. Total span of the bridge is then 143 m. Two variants of the bearing steel structure are compared in the preliminary structural design, in the first one a twin-girder is designed and in the second one a box-girder bridge is assessed. The width of the bridge is 14 m and a launching of the bridge without temporary supports is chosen as the assembly method. The design of the bridge structure was carried out according to the valid standard ČSN EN. The final thesis contains variant design, structural design report, where a bill of quantities is stated, engineering report and drawings.

As vigas de rolamento são estruturas destinadas ao suporte de pontes rolantes, estas amplamente utilizadas para movimentação de cargas em galpões industriais. O presente trabalho apresenta um estudo sobre as vigas de rolamento de aço sem contenção lateral entre apoios, em geral projetadas com vão inferior a 7 metros, portanto destinadas ao suporte de pontes rolantes leves (capacidade nominal até 250 kN). A ausência de contenções laterais intermediárias aliada ao desalinhamento e à imprecisão na locação dos trilhos, bem como à presença de forças horizontais transversais ao eixo da viga (aceleração/frenagem do trole), impõem flexão lateral e torção, esforços que são equilibrados apenas pelas contenções nos apoios. A análise foi realizada utilizando o Método dos Elementos Finitos (MEF), considerando a análise não linear física e geométrica do problema, ou seja, um modelo mais próximo da viga real. Os resultados numéricos, quando comparados aos obtidos por meio da teoria de flexo-torção, mostraram uma inversão na distribuição esperada de tensões na mesa superior do perfil, ou seja, nos pontos onde deveria ocorrer aumento da tensão longitudinal de compressão, ocorreu redução. Esta inversão pode ou não ocorrer, dependendo da espessura da mesa superior, intensidade e posição da força vertical da roda da ponte. Além disso, os resultados determinados via MEF foram comparados com os obtidos via modelo tradicional de barra (momento de torção substituído por um binário de forças horizontais nas mesas). A comparação indicou divergência entre os resultados, podendo o dimensionamento pelo modelo de barra levar tanto a situações a favor da segurança como contra a segurança.
The runway girders are structures intended for support cranes, these broadly used to movement of loads in industrial buildings. This research presents a study about the runway girders without lateral bracing between support points, generally designed with span lower than 7 meters, therefore intended for support of light cranes (rated capacity until 250 kN). The absence of intermediate lateral bracing allied to misalignment and imprecision location of the rail, also the presence of the side thrust on the girder (acceleration/ braking of the trolley), causes lateral flexural and torsion, which are balanced only by the lateral containment on support points. The analysis was made using the Finite Element Method (FEM), which includes a nonlinear physical and geometric analysis of the structural problem, in other words, a model closest to the real girder. The numerical results, when compared to the results of the flexural-torsional theory, showed an inversion in the expected distribution of stress on the top flange of the shape, in other words, at the points where must occur increase of the longitudinal stress, reduction occurred. This inversion may or may not occur, depending on the thickness of the top flange, modulus and position of the load of the crane wheel. Besides, the numerical results were compared with the results of classical bar model for beams (torque is replaced by a couple of horizontal forces applied on the flanges). The comparison showed a divergence between the results, where the design by bar classical model can lead to situations of high safety or against safety.

Thesis (M.S.)--Worcester Polytechnic Institute.
Keywords: structural engineering; fire safety; framework approach; performance-based design; information management; finite element; lumped-parameter; laboratory tests; steel; beam; restrained; plastic analysis. Includes bibliographical references (p. 180-182).

The subject of this thesis is a structural design of a car showroom in municipality Jihlava. For this purpose two different concepts were developed. The main bearing system of the first consists of steel truss girder supported by single profile steel columns. The second idea, a structure with axial ground area 36,0 x 18,5-23,5 m , is made from glue laminated timber. The second mentioned concept was chosen for detailed calculation and documentation. The structure was modelled by 1D member while using Scia Engineer. Results obtained from the computer analysis were taken and main strutctural members were check by manual calculation.

The aim of the thesis is to design and appreciation steel load-bearing structure of motor show. The object is situated in Brno. The Structure consist of tubes and rolling sections. The breadth of construction is 36,5m, lenght 42m and height in the heihest point is 13,2m. The structrure is consists of three parts. Show room, offices and workshop. The height of show room is 20m, offices 8,5m and workshop 8m. The show room consist of arched truss girder. The distance of each cross links is 6 m. Structural design were perfomered by Scia Engineer 2017 and hand computation.

The subject of this diploma thesis is design and check of two steel structures. A production hall with a floor plan dimensions 24x50 m and an administrative building with floor plan dimensions 54x30 m. Both buildings are situated in Prostějov. The structure of the production hall has a roof pitched at 12%. The main frames have 6 m centre to centre spacing. The design of the production hall is processed in two options. The administrative building has 4 floors. The floor structures are made of composite steel and concrete structure. The structure is stabilized by vertical bracings in both directions. The computational model of both structures was built up using SCIA Engineer software.

Fires following earthquake (FFE) have historically produced enormous post-earthquake damage and losses in terms of lives, buildings and economic costs, like the San Francisco earthquake (1906), the Kobe earthquake (1995), the Turkey earthquake (2011), the Tohoku earthquake (2011) and the Christchurch earthquakes (2011). The structural fire performance can worsen significantly because the fire acts on a structure damaged by the seismic event. On these premises, the purpose of this work is the investigation of the experimental and numerical response of structural and non-structural components of steel structures subjected to fire following earthquake (FFE) to increase the knowledge and provide a robust framework for hybrid fire testing and hybrid fire following earthquake testing. A partitioned algorithm to test a real case study with substructuring techniques was developed. The framework is developed in MATLAB and it is also based on the implementation of nonlinear finite elements to model the effects of earthquake forces and post-earthquake effects such as fire and thermal loads on structures. These elements should be able to capture geometrical and mechanical non-linearities to deal with large displacements. Two numerical validation procedures of the partitioned algorithm simulating two virtual hybrid fire testing and one virtual hybrid seismic testing were carried out. Two sets of experimental tests in two different laboratories were performed to provide valuable data for the calibration and comparison of numerical finite element case studies reproducing the conditions used in the tests. Another goal of this thesis is to develop a fire following earthquake numerical framework based on a modified version of the OpenSees software and several scripts developed in MATLAB to perform probabilistic analyses of structures subjected to FFE. A new material class, namely SteelFFEThermal, was implemented to simulate the steel behaviour subjected to FFE events.

The diploma thesis elaborates on the proposal of a loadbearing steel structure of a shopping centre. Four-storey building has total lenght of 88 m, width 48 m and its base structural grid is 8 x 8 m. The total height of building is 25,4 m. First three floors above ground are designed with structural height of 5,6 m whilst the 4TH floor uses height of 4,0 m. Frame structure is formed by primary beams and castellated secondary beams. Above 4TH floor, the roof structure is designed in two alternative versions, both using solid purlins and truss girder. The 3D computer animation of the building is also part of thesis. The shopping centre that is subject of the final thesis is located in Brno area.

[ES] El diseño de puentes, a diferencia de lo que ocurre con el diseño de edificios o con el diseño de túneles ha dejado de lado la consideración de la acción del fuego hasta la fecha. Este vacío normativo, combinado con la gran repercusión económica y social de colapsos de puentes en el pasado como consecuencia de incendios, ha motivado un rápido incremento del número de estudios relativos a la ingeniería frente al fuego en el ámbito de los puentes. Aunque la acción del fuego no resulta del todo desconocida en el ámbito de las estructuras, sí que existen una serie de singularidades que impiden la trasposición directa de recomendaciones o de modelos de fuego simplificados ya desarrollados en otros campos que ya incorporan la acción del fuego en el diseño. En este contexto, el trabajo que a continuación se expone parte de un incendio ocurrido en el estado de Alabama en 2002, cuyas consecuencias fueron la demolición de un puente mixto de 37 metros de vano central, para plantear y validar una metodología que aborda el problema de forma numérica mediante tres modelos acoplados secuencialmente: modelo de incendios, modelo térmico y modelo mecánico Realizada una validación a nivel general se descubre que, aunque la configuración geométrica final obtenida se ajustan bastante a la realidad, la definición del incendio ha supuesto un gran número de hipótesis. Es por ello que se decide, en una segunda parte, realizar una campaña experimental que permita registrar la potencia del fuego, las temperaturas del gas y del acero y las flechas en un puente construido ad-hoc en el campus de la Universitat Politècnica de València. Este puente experimental tenía un vano único de 6 m de luz y fue sometido a cargas de fuego de hasta 1.3 MW. Mediante el empleo de los registros realizados en la campaña experimental se ha validado el modelo de incendio, el modelo térmico y el modelo mecánico. Con todo ello se ha puesto en evidencia la importancia del viento en la acción del fuego, la magnitud de los gradientes térmicos espaciales y la urgencia de desarrollar procedimientos simplificados que permitan la incorporación del fuego como acción en el ámbito de los puentes Las validaciones específicas de cada modelo han permitido además llegar a una serie de conclusiones de gran interés para la realización de futuras campañas experimentales en puentes a mayor escala.
[CAT] El disseny de ponts, a diferència del que passa amb el disseny d'edificis o amb el disseny de túnels ha deixat de banda la consideració de l'acció del foc. Aquest buit normatiu, combinat amb la gran repercussió econòmica i social de col·lapses de ponts com a conseqüència d'incendis, ha motivat un ràpid increment del nombre d'estudis relatius a l'enginyeria del foc del foc en l'àmbit dels ponts. Encara que l'acció del foc no resulta del tot desconeguda en l'àmbit de les estructures, sí que hi ha una sèrie de singularitats que impedeixen la transposició directa de recomanacions o de models de foc simplificats ja desenvolupats en altres camps que ja incorporen l'acció del foc al disseny. En aquest context, el treball que a continuació s'exposa part d'un incendi ocorregut a l'estat d'Alabama en 2002 i que va provocar la demolició d'un pont mixt de 37 metres de va, per plantejar i validar una metodologia que aborda el problema de forma numèrica mitjançant tres models acoplats seqüencialment: model d'incendis, model tèrmic i model mecànic Realitzada una validació a nivell general es descobreix que, encara que la configuració geomètrica final obtinguda s'ajusta en gran mesura a la realitat, la definició de l'incendi ha suposat un gran nombre d'hipòtesis. És per això que es decideix, en una segona part, realitzar una campanya experimental que permeta registrar la potència del foc, les temperatures del gas i de l'acer i les fletxes en un pont construït ad hoc al campus de la Universitat Politècnica de València. Aquest pont experimental presenta un va únic de 6 m de llum i va ser sotmès a càrregues de foc de fins a 1.3 MW. Mitjançant l'ús dels registres realitzats a la campanya experimental s'ha validat el model d'incendi, el model tèrmic i el model mecànic. Amb tot això s'ha posat en evidència la importància del vent en l'acció del foc, la magnitud dels gradients tèrmics espacials i la urgència de desenvolupar procediments simplificats que permetin la incorporació del foc com a acció en l'àmbit dels ponts Les validacions específiques de cada model han permès a més arribar a una sèrie de conclusions de gran interès per a la realització de futures campanyes experimentals en ponts a major escala.
[EN] To date, the fire action has been left aside in the bridge design despite this action has been widely considered in other structures such as building and tunnels. This regulatory vacuum, combined with the great economic and social impact of bridge collapses in recent times as a result of fires, has led to a rapid increase in the number of studies related to fire engineering in the field of bridges. Although the action of fire is not entirely unknown in the field of structures, there are a number of singularities that prevent the direct transposition of recommendations or simplified fire models from such fields. In this context, the study started by using a real fire which occurred in the state of Alabama in 2002 and led to the demolition of the 37-meter main span of a composite concrete and steel bridge to introduce and validate a methodology that numerically addresses the problem by uncoupling the problem in three different models: fire model, thermal model and mechanical model. Once the validation was accomplished at a general level, it was discovered that, although the geometrical data were quite adjusted to reality, the definition of the fire had involved a large number of hypotheses. That is why carrying out an experimental campaign to record the power of the fire, the gas and steel temperatures and the vertical deflections of a bridge built ad-hoc on the campus of the Universitat Politècnica de València became a priority. This 6-meter single span experimental bridge was subjected to fire loads of up to 1.3 MW. Through the use of the information recorded during the experimental campaign, the fire model, the thermal model and the mechanical model were validated. Moreover, the importance of wind in the action of fire, the magnitude of spatial thermal gradients and the urgency of developing simplified procedures which allow the consideration of fire as an action in the field of bridges were also highlighted. Last but not least, the validation of the different models allowed the author to include useful guidelines in order to define future experimental campaigns with more powerful fires and longer span bridges.
Alós Moya, J. (2018). Análisis de la respuesta frente al fuego de puentes mixtos multijácena [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/116625
TESIS

Thesis deals with design of a steel structure of multi-storey office building. It is a six-storey steel structure of square plan with dimensions of 40 x 48 meters and height of 21,5 meters. Structural design report is made by a combination of manual calculations and calculations using software Scia engineer. Structural design report includes calculations of: truss girder, column, connection, bracing, beam, secondary beam and column anchorage. Thesis includes drawing documentation and report.

This thesis deals with design of steel structure multi-storey garage. It is the five-storey steel structure of rectangular plan. The construction is designed for the city of Olomouc. Static calculation is solved by a combination of manual calculation and calculation using software Scia engineer 18. There are the following main load bearing structural elements designed and examined in the structural analysis: truss, purlin, bracing, column, composite beam, joints, foot and anchoring. Thesis includes drawing documentation

The subject of the master´s thesis is the design and assessment of the static load-bearing steel structure office building. It is an eight-storey building with a floor plan and dimensions 54x15m. The proposal has three variants. In one of them a steel frame with a hinge attached elements. These are the pillars, beams, trusses, joists and purlins, which are coupled with trapeze plate and thereby secure the stability of the position in the horizontal direction. The steel structure is placed between the reinforced concrete towers.

碩士
國立交通大學
工學院碩士在職專班產業安全與防災組
97
As steel structural bridge weighs lighter,makes construction faster. Also, evenness in material quality, constructional material of the same intensity, and the variety of models and appearance,makes it most suitable for great span, for construction in urban district and also, quick restoration of damaged bridges.Therefore, we look forward to the future construction of steel structural bridge, especially the box-girder, to become an important position in civil engineering, In view of this, the process in the construction of steel structural box-girder certainly involves of many hidden harmful factors, but the goal of this research is to analyze the use of tools, equipment, the original material & operational sequence,etc. risk analysis; to evaluate and propose of prevention countermeasures. This research applies the job safety analysis measure, to identify of 20 different types of risk in the construction of steel structural box-girder, and which from among, cuts & abrasion, bruises, falling objects, burns, electrification, crashes and etc. 6 categories, account for the highest proportion. Thus, knowing hereby that these 6 harms are the primary factors of job injury in the construction of box-girder, and which both the laborers and employers should be careful of. In addition, having carried out of risk assessment based on risk matrix measure, found a total of 149 cases to have graded the construction of box-girder to be of the greatest risk, and among which, crashes, falling objects, bruises and electrification, to being the 4 harms that account for the highest proportion of risk. Henceforth, should have listed these 4 harms as risks for improvement first. Finally, this research utilized of the inherently safer design strategy in nature, proposed of many substitutions, weakened of countermeasures, for reference by the institution. Hoping to reduce the risk in the construction of steel structural box-girder to an acceptable range, in order to ensure of laborers’ health and job safety.

Built-up steel I-girders are very commonly used in bridge construction. Their spans are typically very long, and they are susceptible to lateral torsional buckling if not enough lateral support is provided. This thesis includes guidelines for preventing lateral torsional buckling of steel I-girders under dead and wind load, accompanied with finite element analysis of double girder systems. The first portion includes capacity envelopes for single girders with single and double symmetric cross sections under various loading conditions and boundary conditions for double and single symmetric cross sections with double girders subjected to dead loads only. The second portion is dedicated to finite element analysis of double girders. Buckling analyses have been conducted on single symmetric double girders to verify their capacity equations and investigate the behavior of double girders subjected to wind load. The analyses focus on the weak axis bending of the double girder system as a whole and an evaluation of whether buckling of cross-bracing is an issue when lateral loads are present.

碩士
國立成功大學
土木工程學系
102
In order to study the post-fire mechanical behaviors of fire-resistant steel and normal structural steel beam-to-column welded joints under cyclic loadings, this thesis made three different types of beam-to-column welded joint specimens by the three different combinations of SN490C-FR fire-resistant steel and SN490B normal structural steel, which were fire-resistant steel specimens, partial fire-resistant steel specimens and normal steel specimens. Each type of specimens were divided to five groups and the five groups experienced five different temperature treatments, which were room-temperature treating, air-cooling after reaching 800ºC for one hour, water-cooling after reaching 800ºC for one hour, air-cooling after reaching 900ºC for one hour, and water-cooling after reaching 900ºC for one hour, respectively to simulate the possible material property variations of weld metal and base metal in the beam-to-column welded connections of steel buildings after fire. As a result, the fifteen beam-to-column welded joint specimens conducted the hardness test first to understand the hardness variations of the pre-fire and post-fire beam-to-column welded joints in the three different types of specimens. After the hardness test, the same fifteen specimens proceeded the cyclic loading test and the followed tensile test to investigate macro mechanical properties and failure modes of the pre-fire and post-fire beam-to-column welded joints in the three different types of specimens. This research found that the specimens with room temperature treating and the specimens with air-cooling after reaching the high temperature above 800ºC for one hour all fractured at the base metal. The air-cooled specimens were equivalent to the specimens with normalizing treating, which softened the base metal and the weld metal. However, the tensile strength of weld metal was still higher than that of base metal. As a result, the fracturing occurred at the base metal. The specimens with water-cooling after reaching the high temperature above 800ºC for one hour all fractured at the weld metal or the HAZ. The water-cooled specimens were equivalent to the specimens with quenching treating. The quenching treating made the austenite in the specimens transform to martensite. The more the martensite in the specimen, the higher the tensile strength of the specimen. The martensite content in a specimen was related to the carbon content of steel. Since the carbon content of base metal was higher than that of weld metal, the strength of base metal was higher than that of weld metal. As a result, the water-cooled specimens in this study fractured at the weld metal or the HAZ.

碩士
國立成功大學
土木工程學系
102
In order to investigate post-fire behaviors of the fire-resistant steel and normal steel beam-to-column welded joints under fast tensile force, this study fabricated three kinds of beam-to-column welded joint specimens by SN490B normal structural steel and SN490C-FR fire-resistant steel, which were fire-resistant steel specimens, normal steel specimens and partial fire-resistant steel specimens. Each kind of the specimens were subject to five different temperature treatments (including room-temperature treating, air-cooling after reaching 800ºC for one hour, water-cooling after reaching 800ºC for one hour, air-cooling after reaching 900ºC for one hour, and water-cooling after reaching 900ºC for one hour) to simulate the post-fire material changes of weld metal and base metal in beam-to-column welded connections. This study conducted macroscopic examination, metallographic test, hardness test and fast tensile test for the specimens. The test results showed that, under the fast tensile forces, the normal steel specimen with the temperature treatment of water-cooling after reaching 900ºC for one hour broke at the HAZ between the ESW weld pass and the diaphragm plate with the failure mode of brittle fracture. The partial fire-resistant steel specimen broke at the HAZ between the FCAW weld pass and the beam flange plate with the failure mode of brittle fracture as well. Due to lack of fusion in the ESW weld pass, the fire-resistant steel specimen fractured at the lack of fusion zone between the ESW weld pass and the diaphragm plate with the failure mode of brittle fracture. All the other specimens broke at the base metal of beam flange plate or diaphragm plate.

碩士
國立成功大學
土木工程學系
103
This study used a 3D nonlinear finite-element software to develop simplified numerical models of the cross-shaped weld zones of beam-to-column welded joints, and to performed numerical simulations of the simplified cross-shaped weld zone numerical models for investigating the post-fire mechanical behaviors of the cross-shaped weld zones of fire-resistant and normal structural steel beam-column joints under tensile-compressive cyclic loadings. In addition, the strain hardening parameters of the fire-resistant grade and normal grade steel materials and weld metals under cyclic loading before and after fire were incorporated into the numerical models to simulate the cyclic loading test results of the fifteen simplified cross-shaped specimens. The fifteen specimens were composed of three types of steel allocations (i.e., fully normal structural steel allocation, partially fire-resistant steel allocation and fully fire-resistant steel allocation) and five temperature treatments (i.e., room-temperature treatment, air-cooling after reaching 800ºC for 1 hour, water-cooling after reaching 800ºC for 1 hour, air-cooling after reaching 900ºC for 1 hour, and water-cooling after reaching 900ºC for 1 hour). The numerical simulation results were compared with the realistic test results for the related investigations. This study found that compared with the test results, the numerical results damaged earlier and their maximum tensile forces were 10% to 15% lower. Therefore, the numerical results were more conservative.

碩士
國立成功大學
土木工程學系碩博士班
98
In recent years, light steel structure has been widely being used in foreign countries. Among its merits are that it is lightweight, easy to construct, and excellent seismic performance. However, when subjected to high temperature in room fires, the material strength would be substantially reduced. Therefore, it is essential to learn about its structural behaviors at a fire scene. This study has conducted structural behavior analysis on the units of Box-structured Light Steel House in an actual room fire. A room fire test on the single unit of the Box-structured Light Steel House was conducted based on CNS 12514 specifications, and FEM (Finite Element Method) numerical simulations were then used to analyze its structural deformation behaviors under the room fire environment by using ANSYS as the simulation tool. Regarding the material properties used in the simulations, as the steel properties of high-temperature of the test specimen have not been available, and that such relevant information is not fully available domestically, the European norm EUROCODE 3 of steel property under a high-temperature environment was adopted to work. The main purpose of this study is to unveil the various temperatures within the room air and on the structural parts during a typical room fire, to establish and verify the numerical simulation analysis, and the structural behaviors of the units of Box-structured Light Steel House, subjected to different boundary constrains with/without live load. This serves as a reference for follow-up studies on the overall high-temperature behaviors of the Box-structured Light Steel House.