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[pt] Este trabalho teve como objetivo propor um sistema construtivo misto eficiente e econômico para edificações. Foram concebidos dois detalhes de ligação semi-rígida mista, o primeiro para colunas de extremidade, e o segundo para colunas intermediárias, executados no eixo de maior inércia da coluna. A ligação de extremidade motivou o desenvolvimento de um novo elemento de ligação: o conector T-rib. Sua principal função é transmitir a resultante das barras de armadura de flexão nas regiões de momento negativo para a mesa das colunas de extremidade. O presente trabalho também envolveu uma investigação de dois modelos para ligações semi-rígidas: o modelo analítico simplificado de Kishi-Chen, [CHEN93], e o modelo mecânico do Anexo J do EUROCODE3, [EURO98], gerando duas alternativas para modelos semi-rígidos mistos. O primeiro modelo de cálculo, desenvolvido a partir do modelo de Kishi e Chen, [CHEN93], permite o cálculo dos dois detalhes de ligação citados anteriormente. O segundo modelo proposto foi concebido a partir da incorporação das contribuições do conector T-rib, das cantoneiras de alma e das barras de armadura existentes nos dois detalhes de ligação citados anteriormente, já que o modelo original do EUROCODE3, não considera estas componentes. Uma calibração dos modelos propostos foi executada a partir de uma comparação com valores obtidos experimentalmente no presente trabalho. Uma solução alternativa para conectores de cisalhamento de vigas mistas de concreto e aço também foi desenvolvida. Esta solução consistiu na adaptação do conector de cisalhamento perfobond rib utilizado em pontes mistas para uso em edificações correntes. Esta investigação resultou na criação de um novo layout para este tipo de ensaio. Este novo ensaio permitiu a determinar a contribuição dos cilindros de concreto e barras de armadura nos furos do conector perfobond rib e aferiu, pela primeira vez na literatura, a fórmula de resistência ao cisalhamento para este conector proposta por Oguejiofor e Hosain, [OGUE94]. Para caracterizar os possíveis estados de ruína do conector T-rib uma série de seis ensaios foi executada. Esta etapa de trabalho compreendeu o desenvolvimento de um novo tipo de ensaio de arrancamento projetado especialmente para esta investigação. Para avaliar o desempenho global do sistema construtivo proposto foi construído e ensaiado um pórtico plano semi-rígido misto em escala real, executado de modo a permitir a aferição do comportamento real das ligações, do comportamento do conjunto das viga-mistas e das vigas- colunas da estrutura. Este ensaio permitiu a determinação de curva carga versus. Rotação, uma estimativa dos esforços máximos de flexão nas ligações, etc. / [en] This work focused on the development of an efficient and economic composite building system. This was accomplished by the conception of two new composite major axis connection details for external and intermediate columns. The external column connection detail motivated the creation of a new connection element: the T-rib connector. The main purpose of this element is to transmit the reinforcement bars forces directly to the external columns in negative moment regions The present study also comprehended an nvestigation of two semi-rigid connections design models:the simplified analytical model of Kishi-Chen, [CHEN93], and the Eurocode 3 mechanical model,[EURO98], leading to further developments in both structural models. The first proposal extends the Kishi-Chen model, [CHEN93], for the external and intermediate columns connections investigated in this work. The second proposal incorporated the contributions of the T-rib connector, the web angles and the reinforcement bars on the EUROCODE3 model, since they were not originally taken into account. Both model were calibrated against the experimental results produced in the present investigation. An alternative solution for composite beams shear connectors was also developed. This solution consisted of an adaptation of the perfobond rib shear connector, generally used in composite bridges, to residential or commercial building construction. This investigation resulted in the development of a new test layout for the required experiments. These experiments enabled the determination of the individual contribution of the concrete dowels and reinforcement bars used in the perfobond rib connector holes. As far as it is known, these tests enable the calibration and evaluation V of each individual term of the perfobond rib resistance formula proposed by Oguejiofor and Hosain, [OGUE94]. A set of six tests was also made to characterise the T-Rib connector ultimate limit states. This procedure also required the development of a new pullout test procedure and layout especially designed for this purpose. To evaluate the global performance of the proposed building system a full-scale composite semi-rigid portal frame was built and tested up to collapse. The experimental programme provided information on real structural behaviour where the influence of connections, beam as beam column behaviour ads second order efectswere full investigated. This experimental research enabled the determination of: load versus rotation curves, an estimation of the maximum connection s bending forces, etc. / [es] Este trabajo tiene como objetivo proponer un sistema constructivo mixto eficiente y económico para edificaciones. Fueron concebidos dos detalles de llamada semi-rígida-mixta, el primero para columnas de extremidad, y el segundo para columnas intermediárias, ejecutados en el eje de mayor inercia de la columna. La llamada de extremidad motivó el desarrollo de un nuevo elemento de llamada: el conector T rib. Su principal función es transmitir la resultante de las barras de armadura de flexión en las regiones de momento negativo para la mesa de las columnas de extremidad. Este trabajo también investiga dos modelos para conexiones semi rígidas: el modelo analítico simplificado de Kishi Chen, [CHEN93], y el modelo mecánico del Anexo J del EUROCODE3, [EURO98], generando dos alternativas para modelos semi rígidos mixtos. El primer modelo de cálculo, desarrollado la partir del modelo de Kishi y Chen, [CHEN93], permite el cálculo de los dos detalles de llamada citados anteriormente. El segundo modelo propuesto fue concebido a partir de la incorporación de las contribuciones del conector T rib, de las esquineras de alma y de las barras de armadura existentes en los dos detalles de llamada citados anteriormente, ya que el modelo original del EUROCODE3, no considera estas componentes. Los modelos propuestos fueron calibrados a partir de una comparación con valores obtenidos experimentalmente en el presente trabajo. Una solución alternativa para conectores de cisallamento de vigas mixtas de concreto y acero también fue desarrollada. Esta solución consistió en la adaptación del conector de cisallamento perfobond rib utilizado en puentes mixtas para uso en edificaciones corrientes. Esta investigación tuvo como resultado la creación de un nuevo layout para este tipo de ensayo. Este nuevo ensayo permitio determinar la contribución de los cilindros de concreto y barras de armadura en las perforaciones del conector perfobond rib y ajustó, por primera vez en la literatura, la fórmula de resistencia al cisallamento para este conector propuesta por Oguejiofor y Hosain, [OGUE94]. Para caracterizar los posibles estados de ruina del conector T rib, se ejecutó una série de seis ensayos. Esta etapa del trabajo comprendió el desarrollo de un nuevo tipo de ensayo de arranque proyectado especialmente para esta investigación. Para evaluar el desempeño global del sistema constructivo propuesto, fue construido un pórtico plano semirígido mixto en escala real, ejecutado de tal modo que permita el ajuste del comportamiento real de las conexiones, del comportamiento del conjunto de las viga mixtas y de las vigas columnas de la extructura. Este ensayo permitió la determinación de curva carga versus Rotación, una estimativa de los esfuerzos máximos de flexión en las conexiones, etc.

The synthesis and electropositive metal (Y, Lu, La, Zr, Hf) chemistry of two rigid dianionic xanthene-based ligands, 4,5-bis(2,4,6-triisopropylanilido)- -2,7-di-tert-butyl-9,9-dimethylxanthene (XN2) and 4,5-bis(2,4,6-triisopropylphenylphosphido)- 2,7-di-tert-butyl-9,9-dimethylxanthene (XP2) have been explored. The reaction of the pro-ligand H2XN2 with [Y(CH2SiMe2R)3(THF)2] (R = Me or Ph) produced the monoalkyl yttrium complexes [(XN2)Y(CH2SiMe3)- (THF)].(O(SiMe3)2)x (3, x = 1-1.5) and [(XN2)Y(CH2SiMe2Ph)(THF)].(O- (SiMe3)2) (4). Neutral 3 reacted with excess AlMe3 to yield [(XN2)Y{(m- Me)2AlMe2}(THF)].O(SiMe3)2 (5.O(SiMe3)2), which is thermally robust, and transfer of the XN2 ligand to aluminum was not observed. However, [(XN2)- AlMe].(O(SiMe3)2)0.5 (6.(O(SiMe3)2)0.5) was synthesized via the reaction of H2XN2 with AlMe3. Compounds 3, 5 and 6 were characterized by X-ray crystallography, and neutral 3, while being poorly active for ethylene polymerization, was highly active for both intra- and inter-molecular hydroamination with a variety of substrates. The synthesis of the pro-ligand H2XP2 was achieved via reduction of 4,5-bis(2,4,6-triisopropylphenylchlorophosphino)-2,7-di-tert-butyl-9,9-dimethylxanthene (XP2Cl2; 7). Double deprotonation of H2XP2 (8) with excess KH yielded the potassium salt, [K2XP2(DME)2.5] (9), which when stirred in THF followed by recrystallization from hexanes, produced the tetrametallic complex, [K4(XP2)2(THF)4] (10) featuring a central K4P4 cage. The reaction of [K2XP2(DME)2.5] (9) with [YI3(THF)3.5] yielded a mixture of products including [(XP2)YI(THF)2] (11) and tris(2,4,6-triisopropylphenylphosphinidene) (P3Tripp3); pure 11 could be isolated in low yield by extraction with a minimum volume of hexanes or O(SiMe3)2. In the solid state, complex 11 reveals a face-capped trigonal bipyramidal geometry at yttrium, in which the xanthene backbone is planar and adopts a large angle (85 degrees) between the P(1)/C(4)/C(5)/P(2) and P(1)/Y/P(2) planes. Due to the successful synthesis and hydroamination catalysis achieved with the XN2 ligand in combination with yttrium, the chemistry of XN2 was further explored using both smaller (Lu) and larger (La) rare earth elements. The alkane elimination reaction of H2XN2 with [Lu(CH2SiMe3)3(THF)2], followed by crystallization from O(SiMe3)2, yielded [(XN2)Lu(CH2SiMe3)(THF)].(O- (SiMe3)2)1.5 (12.(O(SiMe3)2)1.5). By contrast, lanthanum complexes of the XN2 dianion were prepared by salt metathesis; treatment of H2XN2 with excess KH in DME produced the dipotassium salt, [K2(XN2)(DME)x] (2; x = 2-2.5), and subsequent reaction with [LaCl3(THF)3] afforded [{(XN2)LaCl- (THF)}x].(O(SiMe3)2)0.25x (13.(O(SiMe3)2)0.25x; x = 1 or 2) after crystallization from O(SiMe3)2. Compound 13.(O(SiMe3)2)0.25x reacted with two equivalents of LiCH2SiMe3, to form the dialkyl-`ate' complex, [Li(THF)x][(XN2)- La(CH2SiMe3)2].Toluene.LiCl (14.Toluene.LiCl; x = 3). Both 12 and 14 (x = 4) were structurally characterized by X-ray crystallography, and were evaluated as catalysts for intramolecular hydroamination. While compound 14 showed poor activity, the neutral lutetium alkyl complex, 12, is highly active for both intramolecular hydroamination and more challenging intermolecular hydroamination. Like the yttrium analogue, 3, reactions with unsymmetrical alkenes yielded Markovnikov products. Additionally, it is noteworthy that the activity of 12 surpassed that of 3 in the reaction of diphenylacetylene with 4-tert-butylbenzylamine. The reaction of H2XN2 with [Zr(NMe2)4], followed by crystallization from O(SiMe3)2, yielded [(XN2)Zr(NMe2)2].(O(SiMe3)2)0.5 (15.(O(SiMe3)2)0.5). The zirconium dimethyl complex [(XN2)ZrMe2] (16) was accessed via two routes; either by treatment of 15.(O(SiMe3)2)0.5 with excess AlMe3, or by reaction of 15.(O(SiMe3)2)0.5 with excess Me3SiCl, affording [(XN2)ZrCl2] (17), followed by the subsequent reaction of 17 with 2 equivalents of MeLi. The reaction of 16 with one equivalent of B(C6F5)3 or [CPh3][B(C6F5)4] yielded cationic [(XN2)- ZrMe][MeB(C6F5)3] (18) and [(XN2)ZrMe(arene)][B(C6F5)4] (19; arene = n6-benzene, n6-toluene or bromobenzene), respectively. Both 18 and 19 are active for ethylene polymerization under 1 atm of ethylene at 24 and 80 degree Celcius in toluene, with activities ranging from 23.5{883 kg/(mol.atm.h), yielding polymers with weight average molecular weights (Mw) of 71{88 kg/mol and polydispersities (Mw/Mn) of 3.94-4.67. / Thesis / Doctor of Philosophy (PhD) / Pincer ligands are defined as meridionally-coordinating tridentate ligands, and are typically mono-, di- or tri-anionic. This thesis is focused on the synthesis and reactivity of rigid dianionic pincer ligands with an NON- or POP-donor array, with particular emphasis on rare earth and group 4 transition metal complexes. This work explores the effect that these rigid ligands have on the reactivity of the resulting metal complexes and the thermal stability of the solid state structures. Both neutral and cationic mono alkyl complexes have been isolated, and several are highly active catalysts for intra- and intermolecular hydroamination or ethylene polymerization.

No / The chapter describes the ongoing work on modeling the semi-rigid composite beam-column connections of composite beams with precast hollow core slabs. Using the finite element (FE) software ABAQUS, a three-dimensional (3D) model of a composite joint is set up. The technique of simulating bolt force, endplate, concrete elements, reinforcement, and shear connectors, and the interaction between slabs and steel beams is presented in the chapter. Preliminary results on the steel joint and simplify composite joint are also presented in the chapter. FE model for the bare steel joints and the simplified composite joints are presented, and the result of the simplified composite model showed good agreement with the experimental result but with lower joint stiffness. Further work on the full finite element model of composite joints is still going on.

This paper describes the 3-dimensional finite element modelling of composite connection with steel beams and precast hollow core slab. A finite element model to simulate the structural behaviour of the composite beam was described and was used to study the behaviour of a wide range of composite connections to gain a better understanding of the structural behaviour especially the moment¿rotation characteristic of the connections. Parametric studies were carried out to investigate the structural behaviour with variations in: size of the beam, thickness of the endplate, thickness of column web, depth of precast hollow cored slab and stud spacing. Through the parametric study, the structural behaviour of the composite connection has been discussed in detail, and recommendations for the design purpose has been made.

In this work the morphology, crystallization and melting behavior of novel Dow Chemical propylene-ethylene copolymers were investigated. The incorporation of ethylene units into a polypropylene chain resulted in the decrease in crystallization, melting and glass transition temperatures and overall crystallinity. Based on the shape of heat capacity curves and the dependence of the melting temperature offset on ethylene content, it was concluded that copolymers prepared using different catalyst systems exhibited different ethylene sequence length distributions. The behavior of Dow Chemical propylene-ethylene copolymers was compared to that of copolymers prepared using traditional metallocene and Ziegler-Natta catalysts. The catalyst system used in the preparation of these new copolymers is similar to a metallocene catalyst system. It was demonstrated that ethylene defects are partially included in the polypropylene crystal. The thermodynamic heat of fusion at the equilibrium melting temperature decreased by 44% with an increase in ethylene concentration from 0 mol% to 21.2 mol%. On the basis of calorimetric and density data, the inclusion model based on the Sanchez-Eby crystallization theory was shown to be applicable for the evaluation of the degree of crystallinity. At the same time, inadequacies were found in application of the rigid amorphous fraction model to these copolymers. The formation of gamma-phase crystals was shown to be favored by both an increase in the ethylene content and a decrease in the crystallization rate. Increase in the ethylene content was shown to lead to a decrease in the density, length and thickness of alpha-phase crystals. It was also demonstrated that the cross-hatching morphology is present in all propylene-ethylene copolymers. / Ph. D.