Dissertationen zum Thema „Slotted-in steel plate connections“

The mechanical behavior of timber beams with a slotted-in steel plate is studied by creating anumerical model that can simulate the global bending behavior and the load carrying capacity aswell as the nonlinear plastic fastener force distribution. Experimental results from Material TestingInstitute (MPA), University of Stuttgart were compared with simulation results done at LinnaeusUniversity. The modeling of the timber beams and the mechanical connections is performed withshell, beam, and nonlinear connector elements. Three models were created, where the first modelwas a single-dowel double shear joint model to study the ability to use structural elements in themodeling of the test beams. It was used to simulate some of the basic failure modes in Eurocode5 (EC5). The second model was a beam model used to simulate the bending of a jointed timberbeam with a slotted-in steel plate, where only two connector elements are used to model the jointbehavior of each dowel group. It can be used to study the global deflection and the load carryingcapacity of the timber beams. The third model was a combined beam-shell model where the beamelements are used for the timber parts outside the connection area and the fasteners, while the shellelements are used for the slotted-in steel plate and the timber parts within the connection area.It uses two nonlinear connectors to connect each dowel to the wood and pure coupling to connectthe dowels to the slotted-in steel plate. This model can simulate same things as model two andalso the development of the elasto-plastic shear force distribution in all the dowels. All the modelswere created using parameterized Python scripts, which makes it possible to easily change differentinput parameters.Most of the modeling results show good agreement with both experimental results and with calculated load carrying capacity results for individual dowels according to EC5. The use of thesestructural elements (beam, shell, and connector elements) was found to result in much less computational time compared to the use of solid elements.

Steel joints have always been considered as important parts of any structural steel building because they provide the strong links between the principal structural members. The properties and behaviour of joints in both steel and composite structures have been widely studied for some time. The focus has recently been on improving the design of structural frames by taking advantage of realistic connection moment-rotation response. This has necessitated the development of an effective and practicable methodology to describe steel connection behaviour, despite its inherent complexity. Although, the evaluation of steel connections' performance at ambient temperature has been a continuous research topic, the investigation of steel connections at elevated temperatures has only recently been tackled by researchers. However, the determination of the behaviour, available strength and stiffness of moment connections in fire conditions has been a dominant theme in these research works. Moreover, over a number of years the Component Method has been developed to describe the moment-rotation characteristics of end-plate connections, and the method is now included in Eurocode 3. To date, most of the research conducted on steel connections using the component method has focused on relatively stiff and strong connections - flush end-plates and extended end-plates. The modelling of more flexible ("pinned") connections using the Component Method has not received much attention, since the benefits arising from consideration of their behaviour in overall frame response are usually modest. However, in fire conditions connections are subject to complex force combinations of moment and tying forces, as well as vertical shear forces, and the real behaviour, even of nominally pinned connections, can have a significant effect on the overall response of the frame. To date very little information on the behaviour and the resistance of simple shear connections in fire conditions has been generated. Fin plate shear connections, which are economic to fabricate and easy to use in erection, are among these shear connections which are assumed to act as pins in normal service conditions In this research, the behaviour and robustness of simple fin plate beam-to-column connections has been investigated, under the conditions of catenary tension from highly deflected beams which occurs in fire. In addition, detailed investigations have been made on applying the component method approach to this connection at both ambient and elevated temperatures. ABAQUS software has been selected to create a very detailed 3D finite element model. This is a complex model accounting for material nonlinearity, large deformation and contact behaviour. The connection model has been analysed through the elastic and plastic ranges up to failure. Bolt shear and bending, plate and web bearing have been observed as failure modes. A comparison between available experimental data at ambient and elevated temperatures and FEA results shows that the model has a high level of accuracy. However, by implementing the FE model the opportunity was then available to explore the connection tying resistance and the application of the Component Method to the fin plate connection. An intensive investigation has been conducted to develop a representation of this connection type via a simplified component model, enabling prediction of the connection response at both ambient and elevated temperatures. The three main components of a fin-plate connection have been identified as plate bearing, bolt shearing and web-to-plate friction. These components have been described in detail at ambient and elevated temperatures via intensive parametric FE analyses, leading to a simplified component model of a fin plate connection. This model has been evaluated against FE models of complete fin plate joints. Eventually, a fin plate connection spring model is proposed and successfully evaluated for tying, rotation, and shear actions. The Component Model presented in this research offers an opportunity to explore complicated behaviour of fin plate shear joints, and can be incorporated into frame analysis in fire conditions.

The behaviour of joint in global frames subjected to fire is greatly affected by combination of forces and moments, originating from restraint to thermal expansion as well as large vertical deflection of structural members. In order to facilitate the design process of achieving robustness in simple beam-to-column connection, a componentbased model has been developed for fin-plate connections in this research. The new model represents the realistic behaviour of such connections under the influence of combined forces, together with the high rotations which can occur at the ends of beams, during building fires. The key aspect of the component method is that it characterises the force-displacement properties of each active component at any temperature, as a nonlinear "spring". The temperature-dependent characteristics of each individual component in each bolt row are defined, including the failure mechanism of the weakest component, based on experimental and analytical findings. Primary failure modes adopted for fin plate connections are bearing/block shear of the plates and bolt shear. A major additional complication is force reversal in components, which may occur simply because of temperature change, without any physical reversal of displacement. The Massing Rule has been adopted to incorporate the effect of permanent deformations at any temperature when force reversal occurs. To account for the bolt slip phases, force transitions between tensile and compressive quadrants take place only when positive contact between a bolt and the edge of its bolt hole is re-established. The results of high-temperature tests on the fin-plate connections have been used to verifY the model for isolated joints at ambient and elevated temperatures. The developed component model for the fin-plate connection has been extended for the application of moment-resisting beam splice connection, also known as the "column-tree" system. The component-based connection model has also been used to study joint behaviour in structural sub-frame analyses. Incorporating it into non-linear finite element software will enable engineers to generate the global structural interactions for steel and composite structures in fire scenarios, up to and including connection failure. The new connection element has been validated with reasonable agreement with the available experimental data, showing its capability of capturing the key features of the overall connection interaction in a realistic manner, based on the underlying mechanics, coupled with evidence from experimental data.

In order to predict the behaviour of bolted steel connections, different methods can be applied to calculate the design tension resistance. In this thesis, the tension resistance is evaluated in the context of the so called Component Method according to Eurocode 3 part 1-8. The design approach establishes a unified procedure of modelling steel joints. Each joint configuration is decomposed into its basic components depending on loading type. In order to design the resistance of components subjected to tensile forces, a simple substitute model, the so-called Tstub flange is adopted. The Component Method is rather complicated to apply for all joint configurations. Therefore, the aim of this thesis is to create a brief and facilitated handbook covering the most common types of connections Kadesjös’ engineers deal with. The topic to be studied is rather comprehensive. Thus, this work is only focusing on the resistance calculation of components located in tension zone of HEA-sections in order to go deeper into the equivalent T-stub approach. To get a complete view about the designing procedure, general information about the Component Method are gathered by a literature study. Thereafter, the technical rules for calculation introduced in codes and standards were used to generate a general solution algorithm for two different connection configurations. The calculations have been performed using Mathcad, and the obtained results from a parametric analysis for particular profiles in each example are then summarised in tables and diagrams using Microsoft Excel.
Att förutse skruvförbands beteende kan kräva tillämpning av diverse metoder. Metoderna används för att kalkylera den dimensionerande lastkapaciteten. I denna avhandling värderas lastkapaciteten i enlighet med den så kallade Komponentmetoden från del 1-8 i Eurokod 3. Denna dimensioneringsmetod fastslår en enhetlig procedur när det gäller modelleringen av stålförband. Varje förbandstyp bryts ner till sina baskomponenter med avseende på belastningstypen. För att beräkna den dimensionerande lastkapaciteten för dragbelastade komponenter används en förenklad substitutionsmodell en så kallad T-knut. Komponentmetoden är något komplicerad att tillämpa för alla former av skruvförband. Därmed är den huvudsakliga ambitionen med arbetet att skapa en kortfattad handbok vars syfte är att täcka de vanligaste typerna av skruvförband som Kadesjös konstruktörer använder sig av. Ämnet som kommer att studeras är relativt omfattande, således bestämdes det att i huvudsak sätta fokus på bärförmågan hos komponenter i dragzonen för HEA-profiler och därav dyka djupare i den ekvivalenta T-knutmetodiken. För att få en helhetsbild av dimensioneringsprocessen samlades allmän information om komponentmetoden genom litteraturstudier. Därefter användes dimensioneringsreglerna, presenterade i koder och standarder, för beräkning av lastkapacitet. Dessa utnyttjades för att generera en lösningsalgoritm för två skilda förband. Beräkningen genomfördes med hjälp av beräkningsprogrammet Mathcad. De erhållna resultaten, från en parametrisk analys för särskilda profiler i varje exempel, sammanfattades i form av tabeller och diagram med hjälp av Microsoft Excel.

Shallowly embedded column base connections with unreinforced block out concrete are a common method of connecting steel columns to their foundation. There has been little research done to accurately quantify the effects of this block out concrete on the connection strength and rigidity, and therefore there is nothing to aid the practicing engineer in accounting for this in structural analysis. Due to this lack of understanding, engineers have typically ignored the effects of shallow block out concrete in their analysis, presumably leading to a conservative design. Recent research has attempted to fill this gap in understanding. Several methods have been proposed that seek to quantify the effects of shallow block out concrete on a column base connection. Barnwell proposed a model that predicts the strength of a connection. Both Jones and Tryon used numerical modeling to predict the rotational stiffness of the connection. An experimental study was carried out to investigate the validity of these proposed models. A total of 8 test specimens were created at 2/3 scale with varying column sizes, connection details, and embedment depths. The columns were loaded laterally and cyclically at increasing displacements until the connection failed. The results show that the strength model proposed by Barnwell is reasonable and appropriate, and when applied to this series of physical tests produce predictions that have an observed/predicted ratio of between 0.95 to 1.39. The results also show that methods for estimating the rotational stiffness of the connection at the top of the block out concrete, as proposed by Jones and Tryon also produce reasonable values that had observed/predicted ratios of between 0.93 to 1.47. An alternative model for determining a design value for the rotational stiffness of a shallowly embedded column base plate is also proposed. When the embedment depth to column depth ratio is greater than 1.22, the connection is sufficiently rigid and at small deflections (less than 1% story drift) may be accurately modelled with infinite rotational stiffness (a "fixed" connection) at the base of the column.

Jointless bridges are advantageous in removing mechanical joints which are a known cause of bridge deterioration. Elimination of joints provides a smoother riding surface and removes the possibility of de-icing salts penetrating the deck and corroding the deck reinforcing and underlying bridge superstructure. Jointless bridges are traditionally constructed by monolithically casting the entire bridge deck on beams after they have been erected. However, this process requires extensive in-field formwork and lengthy traffic closures. The Texas Department of Transportation proposes a new method of constructing jointless bridges using prefabricated girder-and-deck units connected on-site with cast-in-place closure pours. This new system will expedite construction and reduce disturbances to the traveling public. The objective of this experimental study was to investigate the behavior of the cast-in-place closure pour slab and to determine if it responds to wheel loads in the same way as a traditional monolithic continuous deck. The effects of the cold joints and discontinuous steel details are the focus of the research work.

碩士
國立交通大學
土木工程系所
94
Buckling-restrained brace (BRB) was widely used and studied because of high levels of energy dissipation in seismic loading. Gusset plates, which connect the BRB to other structural members, experienced unexpected buckling before reaching the ultimate capacity of the BRB. The research, therefore, aimed to investigate buckling strength and inelastic compressive behavior of the gusset plate with various geometry, edge stiffeners, and boundary conditions. A parametric study was performed by the general purpose nonlinear finite element computer program ABAQUS. The research results showed that (1) inelastic compressive behavior of the gusset plate was similar to a cantilever plate in compression load, (2) buckling strength was reasonably predicted based on an inelastic plate buckling equation and buckling coefficient, and (3) design guidelines of the gusset plate in compression were proposed with inclusions of edge stiffeners.

碩士
國立臺灣科技大學
營建工程系
95
This research is aimed at studying the structural behavior of low yielding point (LYP) steel gusset plate connections in steel braced frames. The steel braced frames were designed using the “strong brace - weak gusset“ philosophy. The first series of study is to examine the strength and deformation for the different slenderness of bracing members and the low yielding point steel gusset plate connections. Then, by using the single story one bay frame with diagonal brace and X braces to investigate the seismic behavior between the structures were designed using the “strong brace – weak gusset” and conventional concentrically braced frames. The third part of this study is to proof the practicability in the multi-stories of steel braced frame which was designed using the “strong brace – weak gusset”. Base on the results of this research, guidelines for the design procedure of the low yielding point steel gusset plate connections in the steel braced frames which was designed using the “strong brace – weak gusset”. And to suggest 3 kinds of steel gusset plate connections for structural engineers.

A number of recent research studies have investigated the performance of panel zones in seismic-resistant steel Special Moment Resisting Frames (SMF). These recent studies investigated various options for attaching doubler plates to the column at beam-column joints in SMF for purpose of increasing the shear strength of the panel zone. This previous work was primarily focused on doubler plates that extend beyond the top and bottom of the attached beams, and considered cases both with and without continuity plates. As an extension to this previous research, this thesis explores the situation when a doubler plate is fitted between the continuity plates. The objective of this research was to evaluate various options for welding fitted doubler plates to the column and continuity plates through the use of finite element analysis, and to provide recommendations for design. The development and validation of the finite element model are described, along with the results of an extensive series of parametric studies on various panel zone configurations and attachment details for fitted doubler plates. Based on the results of these analyses, recommendations are provided for design of welds used for attaching fitted doubler plates in the panel zone of SMF systems.
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