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Evaluating Shear links for Use in Seismic Structural FusesFarzampour, Alireza 28 January 2019 (has links)
Advances in structural systems that resist extreme loading such as earthquake forces are important in their ability to reduce damages, improve performance, increase resilience, and improve the reliability of structures. Buckling resistant shear panels can be used to form new structural systems, which have been shown in preliminary analysis to have improved hysteretic behavior including increased stiffness and energy dissipating ability. Both of these characteristics lead to reduced drifts during earthquakes, which in turn leads to a reduction of drift related structural and nonstructural damage. Shear links are being used for seismic energy dissipation in some structures. A promising type of fuse implemented in structures for seismic energy dissipation, and seismic load resistance consists of a steel plate with cutouts leaving various shaped shear links. During a severe earthquake, inelastic deformation and damage would be concentrated in the shear links that are part of replaceable structural fuses, while the other elements of the building remain in the elastic state.
In this study, by identifying the issues associated with general fuses previously used in structures, the behavior of the links is investigated and procedures to improve the behavior of the links are explained. In this study, a promising type of hysteretic damper used for seismic energy dissipation of a steel plate with cutouts leaving butterfly-shaped links subjected to shear deformations. These links have been proposed more recently to better align bending capacity with the shape of the moment diagram by using a linearly varying width between larger ends and a smaller middle section. Butterfly-shaped links have been shown in previous tests to be capable of substantial ductility and energy dissipation, but can also be prone to lateral torsional buckling. The mathematical investigations are conducted to predict, explain and analyze the butterfly-shaped shear links behavior for use in seismic structural fuses. The ductile and brittle limit states identified based on the previous studies, are mathematically explained and prediction equations are proposed accordingly. Design methodologies are subsequently conceptualized for structural shear links to address shear yielding, flexural yielding and buckling limit states for a typical link subjected to shear loading to promote ductile deformation modes. The buckling resistant design of the links is described with the aid of differential equations governing the links' buckling behavior. The differential equations solution procedures are developed for a useful range of link geometries and the statistical analysis is conducted to propose an equation for critical buckling moment.
Computational studies on the fuses are conducted with finite element analysis software. The computational modeling methodology is initially verified with laboratory tests. Two parametric computational studies were completed on butterfly-shaped links to study the effect of varying geometries on the shear yielding and flexural yielding limit states as well as the buckling behavior of the different butterfly-shaped link geometries. It is shown that the proposed critical moment for brittle limit state has 98% accuracy, while the prediction equations for ductile limit states have more than 97% accuracy as well. Strategies for controlling lateral torsional buckling in butterfly links are recommended and are validated through comparison with finite element models. The backbone behavior of the seismic butterfly-shaped link is formulized and compared with computational models. In the second parametric study, the geometrical properties effects on a set of output parameters are investigated for a 112 computational models considering initial imperfection, and it is indicated that the narrower mid-width would reach to their limit states in lower displacement as compared to wider mid-width ones.
The work culminates in a system-level validation of the proposed structural fuses with the design and analysis of shear link structural fuses for application in three buildings with different seismic force resisting systems. Six options for shear link geometry are designed for each building application using the design methodologies and predictive equations developed in this work and as guided by the results of the parametric studies. Subsequently, the results obtained for each group is compared to the conventional systems. The effect of implementation of the seismic links in multi-story structures is investigated by analyzing two prototype structures, with butterfly-shaped links and simple conventional beam. The results of the nonlinear response history analysis are summarized for 44 ground motions under Maximum Considered Event (MCE) and Design Basic Earthquake (DBE) ground motion hazard levels. It is shown that implementation of the butterfly-shaped links will lead to higher dissipated energy compared to conventional Eccentrically Braced Frame (EBF) systems. It is concluded that implementation of the seismic shear links significantly improves the energy dissipation capability of the systems compared to conventional systems, while the stiffness and strength are close in these two systems. / Ph. D. / Structural fuses are replaceable elements of a structure that are designed to yield and protect the surrounding members from damages, and then be accessible and replaceable after a major event. Several studies have indicated that steel plates with cutouts would have advantages for use in structural fuses. Having cutouts in a steel plate would make different shapes inside of the plate, which are called structural links. To have the same yielding condition all over the links, it is tried to better align the capacity of the links with the shape of the demand diagram caused by loading, which would be leading to the efficient implementation of the steel. In general, links are implemented to substantially increase the energy dissipation capacity of a structure and significantly reduce the energy dissipation demand on the framing members of a structure. For these purposes, various shapes have been proposed in this research study. The main feature of a replaceable link system is that the inelasticity is concentrated at the steel link while the beams and columns remain almost elastic. This study investigated the general behavior of the fuses, the applicability of them for space-constrained applications, the flexure, shear and buckling limit states affecting the behavior of the links. The computational analysis methodologies to model the links are explained and confirmed with the behavior of the different experiment tests as well as the proposed brittle limit state prediction equations. Subsequently, the two parametric studies are done to investigate the effect of geometrical properties on the links output results and establish prediction equations. The results from the analytical and computational studies for the seismic links are incorporated for seismic investigation of multi-story buildings. The results of seismic analysis of the two buildings are summarized for 44 ground motions.
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Serviceability performance of steel-concrete composite beamsLawson, R.M., Lam, Dennis, Aggelopoulos, E.S., Nellinger, S. 22 November 2016 (has links)
Yes / For composite beams with low degrees of shear connection, additional deflections occur due to slip in the shear connectors, which can be significant for beams with low degrees of shear connection. A design formula is presented for the effective stiffness of composite beams taking account of the stiffness of the shear connectors, which is compared to measured deflections of 6 symmetric beams and an 11m span composite beam of asymmetric profile. It is shown that the comparison is good when using a shear connector stiffness of 70 kN/mm for single shear connectors and 100 kN/mm for pairs of shear connectors per deck rib. Results of push tests on a range of deck profiles confirm these initial elastic stiffnesses. To ensure that the slip at the serviceability limit state does not lead to permanent deformations of the beam, it is proposed that the minimum degree of shear connection should not fall below 30% for un-propped beams and 40% for propped beams of symmetric cross-section. / European Commission
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Dálniční komorový most / Highway box girder bridgeOndrůšková, Kamila January 2018 (has links)
The subject of the diploma thesis is the bridging design of the valley and Doľanský potok on the D1 motorway in the section Jánovce - Jablonov in Slovakia. Three variants of bridging have been designed and then compared. A post-tensioned construction of the box girder cross section was chosen as the most suitable variant, which was further checked. The static calculation was drawn up according to European standards.
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Nosná konstrukce polyfunkčního domu v Brně / Load bearing structure of multifunctional houseStrnad, Stanislav January 2019 (has links)
Subject of this diploma thesis is to design structural system of multifunctional building in Brno. This apartment building has 4 storey. Main load-bearing elements are concrete ceilings, columns and beams in first and second storey. In third and fourth storey are main load-bearing elements masonry and concrete ceilings with beams. Also there is prestressed beam in first storey. The structure was assessed for ultimate and serviceability limit state acording to standarts and regulation. Drawings and drawings of construction are part of the diploma thesis.
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Návrh přemostění komunikace / Design of the bridge structure across the streetVáša, Jiří January 2019 (has links)
The diploma thesis deals with the design of the motorway bridge over the II / 464 road between Butovice-Bílovec. For the bridging design four variants were made, from which a variant of the slab with longitudinal extensions was selected for further processing. The design assessment was performed for the ultimate limit state and serviceability limit state according to valid standards. Determination of internal forces was performed on the model developed in Scia Engineer 18.0.
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Mostní nadjezd přes rychlostní komunikaci / Overpass bridge across the expresswayBeran, Jakub January 2019 (has links)
The topic of this thesis is detailed design of the supporting structure of a bridge. The final design is chosen out of three variants. It is a single beam structure consisting of 6 spans. The supporting structure is prestressed concrete with post-tensioning technology, the impact of phased construction is considered. the subject of the expertise of the structure is ultimate limit state, as well as service limit state, designed according to the code. The thesis also contains drawings, visualization and Engineering Report of the structure.
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Most přes železniční trať / Bridge ower railway linePrekop, Michal January 2020 (has links)
Diploma thesis is focused on a design of the road bridge of the category S7,5 in cadastral territory of a municipality Polanka nad Odrou. Three preliminary studies have been proposed. Box girder beam with a slant walls were selected for more detailed processing. Construction of the bridge is going to be build by time-dependent analysis on a solid formwork. The calculation of load is done by using computer software Midas Civil 19 v 2.1. and Scia Engineer 19.1. Selected preliminary was assessed according to the recent Europan standards.
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Most nad místní komunikací a potokem / Bridge over a local road and a brookŠvancara, Marek January 2020 (has links)
The topic o thlis thesis is design of the structure of a bridge. The beam structure is chosen from three variants of the solution, the structure is formed by a bracket above the pillars and prepared prestressed beams. Various construction procedures have been verified and assessed for the serviceability and load-bearing limit states according to the applicable standards and regulations. Drawing documentation and static calculation are processed.
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Porovnání variant nádrže ČOV z železobetonu a z předpjatého betonu / Comparison of tank variants from reinforced concrete and prestressed concreteMatuška, Vojtěch January 2020 (has links)
The diploma thesis deals with design and comparison of variants of cast-in-place concrete sewage tank made from reinforced concrete and pre-stressed concrete. The layout of sewage tank is rectangular. The tank is in longitudinal way divided into two chambers. The tank is not roofed and is partialy embedded in the ground. The design for ultimate limit state and for service limit state is made for both variants. There is focus on generation and development of cracks in service limit state. For calcuation of internal forces is used model made in software SCIA Engineer, based on finite element method. The reinforced concrete and pre-stressed concrete versions are compared in last part in term of volumes of materials needed. Also there are proposed possible savings.
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Mostní konstrukce přes údolí / Bridge structure over the valleyHroudná, Denisa January 2019 (has links)
The subject of this diploma thesis is the design of post-tensioned road bridge over the valley. Two preliminary studies have been proposed and one of them was selected for more detailed processing. The selected variant is a box girder with a constant height 2,5 m. The construction id divided into five span and its total lenght is 240 m Span length of construction is 18,0 m. The construction was assessed for ultimate and serviceability limit state acording to standarts and regulation. Drawings and vizualizations ard parts of the diploma thesis.
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