Wong Kitti. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2010-2011, design report." / Includes bibliographical references.

Ho Hung Tai, Kenneth. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2010-2011, design report." / Includes bibliographical references.

published_or_final_version / Architecture / Master / Master of Architecture

published_or_final_version / Architecture / Master / Master of Landscape Architecture

The transformation of Hong Kong into a high-density city has created a unique three-dimensional urban fabric defined through networks of urban activity and infrastructure within tight spatial constraints of mountainous slopes and the island shoreline. In Hong Kong urban development, the government performs a dual role both as landlord and as administrator determining the development agenda. With limited space available for development high land price policies have restricted land supplies and priority is given to ‘economic space’ rather than ‘life space’. This has created a city of mobility based on consumption where privatized public spaces such as shopping malls, corporate plazas and elevated walkways are linked primarily to promote shopping. Public spaces are increasingly managed by private parties, and the degree of publicness of such spaces is often not clearly distinguishable to their potential users. Due to Hong Kong’s population density of approximately 33,000 persons/km2, practices of everyday life are increasingly limited by multiple restrictions controlling the use of spaces that only seem to be public. The district of Central, Hong Kong features an urban network of both publicly and privately maintained elevated pedestrian walkways that provide a secondary circulation space. Designed according to commercial priorities, the walkway system in Central typically links privately owned second floor lobbies with similar owners to promote consumption. Although these regulated spaces are required to allow public access 24 hours a day, pedestrian connectivity seems merely an after thought. In such private public spaces, pedestrians move between consumption nodes through a maze of displays and windows filled with luxury consumer goods. This study takes focus on the walkways in Central thus investigating publicness specifically within the context of Hong Kong's high-density urban fabric, then within a wider context of elevated pedestrian walkway systems in Asian Pacific cities. To this end, this thesis employs an empirical case study methodology consisting of a series of observational studies. Each of these studies publicness transcribed through observations of use, users and use patterns. This study identifies a distinction that underlies the discussion of publicness: that of non-place as opposed to place. The distinction of space and place relates to whether users establish personal relationships to the spaces they use and has drawn much critical attention in urban studies over the past several decades. Places typically provide the stage for social practices. The relationship between place and mobility at an elevated level has however, not been studied in detail yet. As mobile urban populations pass through places more than we dwell in them, a new type of space has emerged to facilitate a ‘frictionless passage’, or non-place. Within this realm of non-place pedestrians pass through zones of movement like passengers experiencing a lack of relationship or disconnectivity with a space. This leads to the question whether elevated pedestrian walkways consisting of spatial flows, movement and transitional zones are only capable of performing as non-places? Can relationships develop between the walkways and their users, making them more than non-places, but places? A case study forms the main part of this thesis and specifically focuses on observing aspect of movement and circulation within Central that determine perceptions of publicness. Findings resulting from this study provide an understanding of the ambiguous nature of spaces in Central. From a background study of elevated pedestrian walkways in six Asian Pacific cities, indicators of publicness are established that provide a framework to distinguish characteristics of elevated pedestrian walkways. In Central, gatherings among domestic helpers are found to contribute to the success of the elevated pedestrian walkway system into urban context. Results of this study indicate that elevated pedestrian walkways can be both places and non-places depending on the publicness of space and suggest how a transition of publicness can occur within such spaces. / published_or_final_version / Architecture / Doctoral / Doctor of Philosophy

Made available in DSpace on 2015-05-14T12:09:44Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1082290 bytes, checksum: 1f7e83bb24335482592d0583b23b2e9b (MD5) Previous issue date: 2008-09-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Footbridges are special works of art, present in large urban centers and along the highways. They are built above the roads to improve the safety of pedestrians and facilitate the flow of traffic, since they eliminate the points of conflict between pedestrians and vehicles. The occurrence of the phenomenon lock-in has implied the closing for repair of footbridges subject to dynamic loading induced by crowds of walking pedestrians. This is because the synchronization between the movement of pedestrians and the displacement of the structure has resulted in the occurrence of excessive vibration, when the frequency of excitation generated due to walking is close to the natural frequency of the footbridge. Despite several works about the lock-in, little has been concluded to try to develop a mathematical model to represent the onset of the phenomenon. In principle, another type of synchronization, which occurs among pedestrians, due to densification in crowd situations, would start rising vibrations in the structure, initiating the lock-in. However, there is a lack of experimental data in the literature to prove that theory. An experimental study on the synchronization between pedestrians due to densification was carried out in this research. Experimental tests were conducted on a prototype footbridge with different densities of pedestrians. For the densities investigated (0,3, 0,7 and 0,9 pedestrians/m²) with the pedestrian walking with their natural pacing rate, no evidence of synchronization was found. Tests were also conducted with induced pacing rate, to check the robustness of the methodology used. The results showed that the procedure adopted was valid and can be applied to other densities of interest. / As passarelas são obras de arte especiais, presentes nos grandes centros urbanos e ao longo das rodovias. Tratam-se de travessias em desnível construídas para aumentar a segurança dos pedestres e facilitar o fluxo de tráfego, já que eliminam os pontos de conflito entre pedestres e veículos. A ocorrência do fenômeno lock-in tem levado à interdição para reparos passarelas sujeitas ao carregamento dinâmico induzido por multidões de pedestres ao caminhar. Isso porque a sincronização entre o movimento dos pedestres e os deslocamentos da estrutura tem resultado na ocorrência de vibrações excessivas, nos casos em que a freqüência de excitação produzida pelo caminhar dos pedestres se aproxima da freqüência natural da passarela. Apesar de diversas pesquisas a respeito do lock-in, os resultados ainda são escassos para embasar o desenvolvimento de modelos matemáticos que representem o fenômeno. A princípio, um outro tipo de sincronização, que ocorre entre pedestres em situações de multidão, devido à densificação, daria início às vibrações na estrutura que originariam o lock-in. Contudo, faltam na literatura dados experimentais que comprovem essa teoria. Um estudo experimental a respeito da sincronização entre pedestres devido à densificação foi feito nesta pesquisa. Testes experimentais foram realizados num protótipo de passarela com diferentes densidades de pedestres. Para as densidades investigadas (0,3, 0,7 e 0,9 pedestres/m²), com os pedestres caminhando com sua taxa de passo natural, nenhum indício de sincronização foi verificado. Também foram realizados testes com taxa de passo induzida para verificar a robustez da metodologia utilizada. Os resultados mostraram que o procedimento adotado é válido e pode ser aplicado para outras densidades de interesse.

Master of Architecture

M.Tech. (Architectural Technology) / This dissertation is rooted within the process of analysing and understanding the dynamics of the context, from which principles can be drawn. The project is founded with the aim to address the harsh edges between Kliptown informal settlement and Kliptown CBD, which are physically separated by railway tracks. This dissertation identifies the context as the ‘bank’ of design informants. Thus it forces the author to undergo a critical analysis of the context. The proposed site (Kliptown) forms a comprehensive layer of history, which has over time influenced both physical development and movement of the site. The project propose a physical intervention in a form of a bridge over the railway tracks in attempt to connect the two areas. The author engaged with the context to establish program for the architectural intervention. The education gap was established within the informal settlement, which was then used to establish the program for the intervention. The average shack size of 15 square meters is never enough for learners to do they school work after schooling hours, thus the proposed programme of the physical bridge forms part of the bridging concept. The program is more about bridging the educational gap within the context.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A experiência dos engenheiros estruturais e os conhecimentos adquiridos pelo uso de materiais e novas tecnologias, têm ocasionado estruturas de aço e mistas (aço-concreto) de passarelas cada vez mais ousadas. Este fato tem gerado estruturas de passarelas esbeltas, e consequentemente, alterando os seus estados de limite de serviço e último associados ao seu projeto. Uma consequência direta desta tendência de projeto é o aumento considerável das vibrações das estruturas. Portanto, a presente investigação foi realizada com base em um modelo de carregamento mais realista, desenvolvido para incorporar os efeitos dinâmicos induzidos pela caminhada de pessoas. O modelo de carregamento considera a subida e a descida da massa efetiva do corpo em cada passo. A posição da carga dinâmica também foi alterada de acordo com a posição do pedestre sobre a estrutura e a função do tempo gerada, possui uma variação espacial e temporal. O efeito do calcanhar do pedestre também foi incorporado na análise. O modelo estrutural investigado baseia-se em uma passarela tubular (aço-concreto), medindo 82,5m. A estrutura é composta por três vãos (32,5 m, 20,0 m e 17,5 m, respectivamente) e dois balanços (7,5 m e 5,0 m, respectivamente). O sistema estrutural é constituído por perfis de aço tubular e uma laje de concreto, e é atualmente utilizada para travessia de pedestres. Esta investigação é realizada com base em resultados experimentais, relacionando a resposta dinâmica da passarela com as obtidas via modelos de elementos finitos. O modelo computacional proposto adota as técnicas de refinamento de malha, usualmente presente em simulações pelo método de elementos finitos. O modelo de elementos finitos foi desenvolvido e validado com resultados experimentais. Este modelo de passarela tubular permitiu uma avaliação dinâmica completa, investigando especialmente ao conforto humano e seus limites de utilização associados à vibração. A resposta dinâmica do sistema, em termos de acelerações de pico, foi obtida e comparada com os valores limites propostos por diversos autores e padrões de projeto. As acelerações de pico encontradas na presente análise indicou que a passarela tubular investigada apresentou problemas relacionados com o conforto humano. Por isso, foi detectado que este tipo de estrutura pode atingir níveis de vibrações excessivas que podem comprometer o conforto do usuário na passarela e especialmente a sua segurança. / The structural engineers experience and knowledge allied by the use newly developed materials and technologies have produced steel and composite (steel-concrete) footbridges with daring structures. This fact have generated very slender structural footbridges and consequently changed the serviceability and ultimate limit states associated to their design. A direct consequence of this design trend is a considerable increase of structural vibrations. Therefore, the present investigation was carried out based on a more realistic load model developed to incorporate the dynamic effects induced by people walking. The load model considered the ascent and descending movement of the human body effective mass at each step. The position of the dynamic load was also changed according to the individual position and the generated time function, having a space and time description. The effect of the human heel was also incorporated in the analysis. The investigated structural model was based on a tubular composite (steel-concrete) footbridge, spanning 82.5 m. The structure is composed by three spans (32.5 m, 17.5 m and 20.0 m, respectively) and two overhangs (7.5 m and 5.0 m, respectively). The structural system is constituted by tubular steel sections and a concrete slab and is currently used for pedestrian crossing. This investigation is carried out based on correlations between the experimental results related to the footbridge dynamic response and those obtained with finite element models. The proposed computational model adopted the usual mesh refinement techniques present in finite element method simulations. The finite element model has been developed and validated with the experimental results. This model enabled a complete dynamic evaluation of the investigated tubular footbridge especially in terms of human comfort and its associated vibration serviceability limit states. The system dynamic response, in terms of peak accelerations, was obtained and compared to the limiting values proposed by several authors and design standards. The peak accelerations found in the present analysis indicated that the investigated tubular footbridge presented problems related with human comfort. Hence it was detected that this type of structure can reach high vibration levels that can compromise the footbridge users comfort and especially its safety.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A experiência dos engenheiros estruturais e os conhecimentos adquiridos pelo uso de materiais e novas tecnologias, têm ocasionado estruturas de aço e mistas (aço-concreto) de passarelas cada vez mais ousadas. Este fato tem gerado estruturas de passarelas esbeltas, e consequentemente, alterando os seus estados de limite de serviço e último associados ao seu projeto. Uma consequência direta desta tendência de projeto é o aumento considerável das vibrações das estruturas. Portanto, a presente investigação foi realizada com base em um modelo de carregamento mais realista, desenvolvido para incorporar os efeitos dinâmicos induzidos pela caminhada de pessoas. O modelo de carregamento considera a subida e a descida da massa efetiva do corpo em cada passo. A posição da carga dinâmica também foi alterada de acordo com a posição do pedestre sobre a estrutura e a função do tempo gerada, possui uma variação espacial e temporal. O efeito do calcanhar do pedestre também foi incorporado na análise. O modelo estrutural investigado baseia-se em uma passarela tubular (aço-concreto), medindo 82,5m. A estrutura é composta por três vãos (32,5 m, 20,0 m e 17,5 m, respectivamente) e dois balanços (7,5 m e 5,0 m, respectivamente). O sistema estrutural é constituído por perfis de aço tubular e uma laje de concreto, e é atualmente utilizada para travessia de pedestres. Esta investigação é realizada com base em resultados experimentais, relacionando a resposta dinâmica da passarela com as obtidas via modelos de elementos finitos. O modelo computacional proposto adota as técnicas de refinamento de malha, usualmente presente em simulações pelo método de elementos finitos. O modelo de elementos finitos foi desenvolvido e validado com resultados experimentais. Este modelo de passarela tubular permitiu uma avaliação dinâmica completa, investigando especialmente ao conforto humano e seus limites de utilização associados à vibração. A resposta dinâmica do sistema, em termos de acelerações de pico, foi obtida e comparada com os valores limites propostos por diversos autores e padrões de projeto. As acelerações de pico encontradas na presente análise indicou que a passarela tubular investigada apresentou problemas relacionados com o conforto humano. Por isso, foi detectado que este tipo de estrutura pode atingir níveis de vibrações excessivas que podem comprometer o conforto do usuário na passarela e especialmente a sua segurança. / The structural engineers experience and knowledge allied by the use newly developed materials and technologies have produced steel and composite (steel-concrete) footbridges with daring structures. This fact have generated very slender structural footbridges and consequently changed the serviceability and ultimate limit states associated to their design. A direct consequence of this design trend is a considerable increase of structural vibrations. Therefore, the present investigation was carried out based on a more realistic load model developed to incorporate the dynamic effects induced by people walking. The load model considered the ascent and descending movement of the human body effective mass at each step. The position of the dynamic load was also changed according to the individual position and the generated time function, having a space and time description. The effect of the human heel was also incorporated in the analysis. The investigated structural model was based on a tubular composite (steel-concrete) footbridge, spanning 82.5 m. The structure is composed by three spans (32.5 m, 17.5 m and 20.0 m, respectively) and two overhangs (7.5 m and 5.0 m, respectively). The structural system is constituted by tubular steel sections and a concrete slab and is currently used for pedestrian crossing. This investigation is carried out based on correlations between the experimental results related to the footbridge dynamic response and those obtained with finite element models. The proposed computational model adopted the usual mesh refinement techniques present in finite element method simulations. The finite element model has been developed and validated with the experimental results. This model enabled a complete dynamic evaluation of the investigated tubular footbridge especially in terms of human comfort and its associated vibration serviceability limit states. The system dynamic response, in terms of peak accelerations, was obtained and compared to the limiting values proposed by several authors and design standards. The peak accelerations found in the present analysis indicated that the investigated tubular footbridge presented problems related with human comfort. Hence it was detected that this type of structure can reach high vibration levels that can compromise the footbridge users comfort and especially its safety.