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Better public housing management in Ghana: An approach to improve maintenance and housing quality
Get PDFAdequate housing and shelter have been recognised by the United Nations (UN) as a human right. All signatory countries to the Universal Declaration on Human Rights are enjoined to take steps to provide decent and adequate housing to their people. To this end, the UN has led and advocated various policy initiatives aimed at addressing housing challenges globally. In the 1950s, it advocated direct housing production by member states. Since the 1970s, it has advocated the enablement approach, encouraging governments to create the enabling environment for the private sector to provide housing. Ghana’s housing policy has changed largely in line with global trends. In the 1950s, the State Housing Corporation (SHC) and the Tema Development Corporation (TDC) were established to lead governmental direct housing provision. However, in the late 1970s and 1980s, when national housing policy shifted towards the enablement approach, most (more than 90%) of public housing was sold to sitting tenants and institutions, and the TDC and SHC were reconstituted into private companies owned by the government. The remainder of the public houses were transferred to local authorities (LAs) to manage. The United Nations has emphasised not only housing production but also maintenance as a sustainable way of meeting the goal of decent and adequate housing. From this point of view, it is possible to reflect on that aspect of public housing managed by local authorities in Ghana. Several researches and commentaries about Ghana’s public housing have highlighted the poor and deteriorating quality, largely due to lack of maintenance. They make reference to leaking roofs, rotten ceilings, cracked walls, faded paint, and dysfunctional electrical and plumbing systems, among other problems in public housing. However, not much research has focused on how to address the problem of lack of maintenance. It is within this context that this PhD research has sought to extend the discussion and contribute practical steps to address the problem of lack of maintenance in public housing.
Therefore, the aim of this PhD research was to propose an approach to public housing management (HM) by LAs that may bring about maintenance and lead to better housing quality in Ghana. To do that, four research questions were addressed. (1) How is housing management by LAs organised, and how have challenges therein affected the quality of public housing? (2) What factors can be distinguished to describe the organisation of and assess performance in HM? (3) What lessons can be learned from the organisation and practice of HM in other contexts? and (4) How can the lessons learned from other contexts be applied to housing by local authorities in order to bring about maintenance that may lead to improvement in public housing quality in Ghana? A pragmatic approach was adopted for this research, within which case studies, lesson drawing, and transferability strategies were applied.
The methods of data collection and analyses were largely qualitative, with minimal application of quantitative techniques.
The research combined the organisational elements of policy/strategy, legal framework, organisational structure, financial resources, human resources, culture, and housing quality; the categorisation of HM activities into technical, social, and financial; and external context factors, which may include regulatory and policy environment and cultural factors that affect HM, into a framework to analyse the organisation and management of housing. Also, the research found that, in general, performance in HM may be assessed by using indicators such as: quality of maintenance, responses from staff in relation to tenant services, and access to information by tenants, which measure effectiveness; cost of maintenance per dwelling and net rent as measures of efficiency and economy; application procedures, rent levels, and support for tenants as measures of equity; and the level of participation and the frequency and ease of communication with tenants as measures of legitimacy and support for HM. However, the research relied on information about effectiveness — maintenance and repairs, tenant services, and legitimacy and support — tenant participation, to comment on the performance of HM.
The research first sought to understand the challenges of public HM and maintenance by local authorities. It found that, among others, public HM confronts the following key challenges: There is no clearly defined institutional structure for HM. There is no coordination of roles performed by the housing officer of the central administration of the local authority, the works department, and tenants. Also, there is no coordination between local authorities that are responsible for management and the central government agency that collects rents, the Controller and Accountant Generals Department (CAGD). Furthermore, local authorities lack funds necessary for maintenance because rents are largely collected by central government and not transferred to them. Additionally, inadequate numbers of professionals are available to manage and maintain public houses.
Informed by the problems of public HM in Ghana, two models of HM were selected and studied to draw lessons for solving the problems in Ghana. The purpose of the studies was to abstract principles from the organisation and practice of HM by identifying issues that need to be addressed for effective housing management and maintenance. Housing management by housing associations (HAs) in the Netherlands and council housing management by tenant management organisations (TMOs) in England were studied. HAs are independent not-for-profit professional housing associations that provide housing mainly for low- and middle-income households in the Netherlands. Wonen Wateringen (WW) housing association was studied in this model. The main principles abstracted from this model were that regulatory and policy guidance are in place, mechanisms to monitor and supervise HM are in place, there is financial security for HM, rents are able to cover housing management and maintenance, there are a defined structure and operational procedures and responsibilities, professionals manage housing, and mechanisms for tenants to participate are in place.
TMOs are tenant organisations formed to take on the responsibility of providing some HM services of local councils or HAs in England. Common services that TMOs take on include repairs and maintenance (mainly day-to-day complaints repairs and void maintenance), cleaning, caretaking, tenancy management, estate services, and other non-housing services, such as skills training and finance support services. Roman Way Estate Community Interest Company (RWECIC) and Bloomsbury Estate Management Board (BEMB) in Birmingham, England, were studied in this model. The main principles abstracted from this model include: laws, regulations, and codes in place to guide HM; secure finance for housing management; rents that are able to cover housing services; a defined structure and responsibilities of stakeholders; defined mechanisms for supervision and monitoring; professionals carrying out HM; defined protocols to address repairs and maintenance; defined maintenance responsibilities of tenants and managers; and mechanisms to involve tenants.
These principles were then applied as guides to formulate solutions that address the challenges identified in Ghana and presented as a preliminary HM approach. The preliminary approach was further developed through an iterative validation and review process with tenants and local-authority housing professionals in Ghana to produce a final HM approach. By proposing this approach to be implemented by LAs so as to bring about maintenance and lead to improvement in public housing quality, the goal of the research is attained. The HM approach highlights and recommends a defined structure to manage public houses. The actors in the structure include the district assembly, the coordinating director, the housing unit, the works department, and tenants, whose roles, responsibilities, and relationships are clearly defined. Further, the structure outlines a defined protocol for addressing repairs and maintenance, which includes a mechanism to receive and promptly respond to repair requests from tenants. Another key recommendation of the approach is for local authorities to take full responsibility for rents determination and collection, in order to ensure reliable and secure finance for HM. Rents should be determined by reference to house properties and condition, and rents should be collected through direct bank debit into a rent account of the district. Mechanisms such as planning, budgeting, and submission of annual accounts of receipts and expenditure are suggested to ensure that rents are spent on maintenance and adequately accounted for. Furthermore, the approach recommends active tenant participation in management through mechanisms such as regular meetings or tenant representatives. In addition, LA communication with tenants should be enhanced by creating opportunities for tenants to make contact and present concerns. For instance, it should be possible for tenants to walk in, write, or call the office responsible for managing the houses and get a response. It also recommends that local authorities use professionals to manage the houses. Where possible — for example, considering the stock size and financial situation — LAs should either recruit or train already employed staff to take full responsibility for the management, in order to give adequate attention to the task of housing management and maintenance. Finally, the research found that lack of commitment on the part of public officers and LAs has led to mistrust and lack of cooperation from tenants. Therefore, it recommends and emphasises the importance of commitment on the part of local authorities, tenants, and national government to the implementation of the HM approach. LAs need to fulfil their part of the approach — for example, by spending rents on maintenance — and tenants also need to carry out their obligations, which include performing tenant maintenance. National government should be committed and grant permission to determine and collect rents to LAs.
The conclusions reached in this research were made under certain limiting conditions. First, it is acknowledged that there could be flaws in the conclusions and principles abstracted from English and Dutch cases because the research may not have obtained a complete view of the models. This potential arises because it was not possible to interview all stakeholders within the limited time of this PhD research. There may have been flaws in the application of the lessons from these cases to a context as different as Ghana. In the respective instances, the research rigorously conducted interviews and checked with interviewees to ensure that the right lessons were learned, and it adopted an iterative process of validation and review to apply the principles to Ghana. Therefore, it is hoped that the impact of these limitations will be mitigated. Also, the research uses the term “validation” merely to refer to comments on the approach made by housing professionals and tenants in the development of the final approach and not as a surrogate for a practical test.
Notwithstanding the limitations of this PhD research, it has contributed to the efforts of other scholars to highlight the societal problem of lack of maintenance in public housing, and it takes the discussion further by presenting an approach to address the problem. This approach has the potential to impact the wider society, if private and other institutional landlords adapt and apply it in their HM. Also, by implementing this approach, LAs may be able to make a positive impact on other public agencies that are faced with lack of maintenance. In addition, it is hoped that the findings of this research may stimulate individuals, public institutions, and society at large to reflect on the attitude toward, commitment to, and responsibility for public property. From a scientific point of view, it may be said that this PhD research has sought to expand the utility of the analytical framework developed and applied in a Western context (see Gruis, Tsenkova, & Nieboer, 2009) by applying it to the context of a developing country.
It also builds on knowledge of lesson drawing and the transferability of programmes (see Rose, 2001) from one context to another. The thesis recommends applying the HM approach in a participatory research with local authorities in Ghana. Also, further research may be conducted into the phenomena of the commitment and attitudes of people, especially public officers, with a view to bringing about change. Furthermore, researchers may use the approach to lesson drawing and transferability applied in this research in similar researches to advance the development of process steps for effective lesson drawing and transferability from one context to another
Complex Adaptive Systems & Urban Morphogenesis: Analyzing and designing urban fabric informed by CAS dynamics
Get PDFThis thesis looks at how cities operate as Complex Adaptive Systems (CAS). It focuses on how certain characteristics of urban form can support an urban environment's capacity to self-organize, enabling emergent features to appear that, while unplanned, remain highly functional. The research is predicated on the notion that CAS processes operate across diverse domains: that they are ‘generalized' or ‘universal'. The goal of the dissertation is then to determine how such generalized principles might ‘play out' within the urban fabric. The main thrust of the work is to unpack how elements of the urban fabric might be considered as elements of a complex system and then identify how one might design these elements in a more deliberate manner, such that they hold a greater embedded capacity to respond to changing urban forces. The research is further predicated on the notion that, while such responses are both imbricated with, and stewarded by human actors, the specificities of the material characteristics themselves matter. Some forms of material environments hold greater intrinsic physical capacities (or affordances) to enact the kinds of dynamic processes observed in complex systems than others (and can, therefore, be designed with these affordances in mind). The primary research question is thus:
What physical and morphological conditions need to be in place within an urban environment in order for Complex Adaptive Systems dynamics arise - such that the physical components (or ‘building blocks') of the urban environment have an enhanced capacity to discover functional configurations in space and time as a response to unfolding contextual conditions?
To answer this question, the dissertation unfolds in a series of parts. It begins by attempting to distill the fundamental dynamics of a Complex Adaptive System. It does so by means of an extensive literature review that examines a variety of highly cited ‘defining principles' or ‘key attributes' of CAS. These are cross-referenced so as to extract common features and distilled down into six major principles that are considered as the generalized features of any complex system, regardless of domain. In addition, this section considers previous urban research that engages complexity principles in order to better position the distinctive perspective of this thesis. This rests primarily on the dissertation's focus on complex urban processes that occur by means of materially enabled in situ processes. Such processes have, it is argued, remained largely under-theorized. The opening section presents introductory examples of what might be meant by a ‘materially enabling' environment.
The core section of the research then undertakes a more detailed unpacking of how complex processes can be understood as having a morphological dimension. This section begins by discussing, in broad terms, the potential ‘phase space' of a physical environment and how this can be expanded or limited according to a variety of factors. Drawing insights from related inquiries in the field of Evolutionary Economic Geography, the research argues that, while emergent capacity is often explored in social, economic, or political terms, it is under-theorized in terms of the concrete physical sub-strata that can also act to ‘carry' or ‘moor' CAS dynamics. This theme is advanced in the next article, where a general framework for speaking about CAS within urban environments is introduced. This framework borrows from the terms for ‘imageability' that were popularized by Kevin Lynch: paths, edges, districts, landmarks, and nodes. These terms are typically associated with physical or ‘object-like features' of the urban environment — that is to say, their image. The terminology is then co-opted such that it makes reference not simply to physical attributes, but rather to the complex processes these attributes enable. To advance this argument, the article contrasts the static and ‘imageable' qualities of New Urbanism projects with the ‘unfolding' and dynamic qualities of complex systems - critiquing NU proponents as failing to appreciate the underlying forces that generate the environments they wish to emulate. Following this, the efficacy of the re-purposed ‘Lynchian' framework is tested using the case study of Istanbul's Grand Bazaar. Here, specific elements of the Bazaar's urban fabric are positioned as holding material agency that enables particular emergent spatial phenomena to manifest. In addition, comparisons are drawn between physical dynamics unfolding within the Bazaar's morphological setting (leading to emergent merchant districts) and parallel dynamics explored within Evolutionary Economic Geography).
The last section of the research extends this research to consider digitally augmented urban elements that hold an enhanced ability to receive and convey information. A series of speculative thought-experiments highlight how augmented urban entities could employ CAS dynamics to ‘solve for' different kinds of urban optimization scenarios, leading these material entities to self-organize (with their users) and discover fit regimes. The final paper flips the perspective, considering how, not only material agency, but also human agency is being augmented by new information processing technologies (smartphones), and how this can lead to new dances of agency that in turn generate novel emergent outcomes.
The dissertation is based on a compilation of articles that have, for the most part, been published in academic journals and all the research has been presented at peer-reviewed academic conferences. An introduction, conclusion, and explanatory transitions between sections are provided in order to clarify the narrative thread between the sections and the articles. Finally, a brief ‘coda' on the spatial dynamics afforded by Turkish Tea Gardens is offered
Building Performance Simulation and Characterisation of Adaptive Facades: Adaptive Facade Network
Get PDFThe book “Performance Simulation and Characterisation of Adaptive Facades” responds to the need of providing a general framework, standardised and recognised methods and tools to evaluate the performance of adaptive facades in a quantitative way, by means of numerical and experimental methods, in different domains of interest. This book represents the main outcome of the activities of the Working Group 2 of the COST Action TU1403 Adaptive Façades Network, “Components performance and characterisation methods”, by integrating in one publication the main deliverables of WG2 described in the Memorandum of Understanding: D 2.1. Report on current adaptive facades modelling techniques; D 2.4. Report on the validation of developed simulation tools and models; D 2.5. Report on the developed experimental procedures. These are extended by additional sections regarding structural aspects and key performance indicators for adaptive façade systems.
This book is a comprehensive review of different areas of research on adaptive façade systems and provides both general and specific knowledge about numerical and experimental research methods in this field. The fast pace at which building technologies and materials develop, is slowly but constantly followed by the development of numerical and experimental methods and tools to quantify their performance.
Therefore this book focuses primarily on general methods and requirements, in an attempt to provide a coherent picture of current and near future possibilities to simulate and characterise the performance of adaptive facades in different domains, which could remain relevant in the coming years. In addition, specific know-how on selected cases is also presented, as a way to clarify and apply the more general approaches and methods described. The present book is published to support practitioners, researchers and students who are interested in designing, researching, and integrating adaptive façade systems in buildings. It targets both the academic and the not-academic sectors, and intends to contribute positively to an increased market penetration of adaptive façade systems, components and materials, aimed at rationalising energy and material resources while achieving a high standard of indoor environmental quality, health and safety in the built environment
Case Studies: Adaptive Facade Network
Get PDFAdaptive building envelopes can provide improvements in building energy efficiency and economics, through their capability to change their behaviour in real time according to indooroutdoor parameters. This may be by means of materials, components or systems. As such, adaptive façades can make a significant and viable contribution to meeting the EU´s 2020 targets. Several different adaptive façade concepts have already been developed, and an increase in emerging, innovative solutions is expected in the near future. In this context the EU initiative COST Action TU 1403 aims to harmonize, share and disseminate technological knowledge on adaptive facades at a European level.
According to the definition given by this COST Action, an adaptive façade is a building envelope consisting of multifunctional and highly adaptive systems that is able to change its functions, features, or behaviour over time in response to transient performance requirements and boundary conditions, with the aim of improving the overall building performance.
In order to explore the available and emerging technologies focusing on adaptive façades, Working Group 1 of the COST Action undertook research to form a database of adaptive façade case studies and projects structured in accordance with a simple classification — materials, components and systems. In addition to this, details of the purpose of the systems/components/materials with adaptive features and the working principle of each technology were also collected together with data regarding design practice, technology readiness, and economical aspects, among others.
The information was collected with the help of a specific online survey (structured in the following main sections: detailed description - metrics- characterization- economic aspects — references). The database includes 165 cases of adaptive façade systems, components, and materials that allowed a variety of analyses to be carried out. According to the classification adopted within WG1 (materials, components, systems), each of the classification terms are introduced together with examples from the case study database in the following sections. This volume ends with a section dedicated to future developments, where different issues are addressed such as embedded functionality and efficiency amd biomimetic inspirations. The importance of adaptive façades through their flexibility, and intelligent design within the context of smart cities is also discussed.
The work within Working Group 1 - Adaptive technologies and products was developed within four distinct sub-groups (SG) in order to provide outputs according to the objectives of this WG and the COST Action: SG1 — Database, SG2 — Educational Pack, SG3 — Publications and Reports and SG4 — Short Term Scientific Missions (STSM).
This work was possible due to the strong commitment and work of all WG1 members: Laura Aelenei, Aleksandra KrstiÇ-FurundžiÇ, Daniel Aelenei, Marcin Brzezicki, Tillmann Klein, Jose Miguel Rico-Martínez, Theoni Karlessi, Christophe Menezo, Susanne Gosztonyi, Nikolaus Nestle, Jerry Eriksson, Mark Alston, Rosa Romano, Maria da Glí³ria Gomes, Enrico Sergio Mazzucchelli, Sandra Persiani, Claudio Aresta, Nitisha Vedula, Miren Juaristi
Spatial Quality as a decisive criterion in flood risk strategies: An integrated approach for flood risk management strategy development, with spatial quality as an ex-ante criterion
Get PDFThe role of the designer in flood risk management strategy development is currently often restricted to the important but limited task of optimally embedding technical interventions, which are themselves derivatives of system level flood risk strategies that are developed at an earlier stage, in their local surroundings. During this thesis research, an integrated approach is developed in which spatial quality can already be included in the regional flood risk management strategy development, and thus can become a decisive ‘ex-ante’ aspect of flood risk management strategy development.
The key principle to this approach is the inclusion of a range of interchangeable (effective) flood risk reduction interventions at varying locations, so that the criterion of spatial quality can become decisive in flood risk management strategy development. As part of the methodology development, an assessment framework is developed, allowing for the assessment of the impact of the different interventions on spatial quality; research-by-design is employed to systematically evaluate different interventions at different locations. The Rijnmond-Drechtsteden area in The Netherlands is used as a case study area for this research
Designerly Ways of Urban Thinking: Farewell Speech
Get PDFFarewell speech. Delivered in a shortened version March 7 2014 on the occasion of his retirement as professor of Urban Design at the Faculty of Architecture and the Built Environment of the Delft University of Technology
De toekomstige rol van de architect: een wetenschappelijke ontwerpgids
Get PDF‘De toekomstige rol van de architect’ beschrijft de essentie van onze wetenschappelijke verkenning naar nieuwe rolstructuren in de Nederlandse architectenbranche. Deze verkenning is uitgevoerd in het kader van het futurA project, dat verwijst naar future value chains of architectural services. Vier jaar lang hebben we vanuit de Technische Universiteit Delft en Radboud Universiteit Nijmegen in nauwe samenwerking met de BNA onderzoek gedaan naar de toekomstbestendigheid van de rollen die architectenbureaus in het bouwproces vervullen.
Het futurA project is í©í©n van de 23 projecten die vanuit NWO, de Nederlandse Organisatie voor Wetenschappelijk Onderzoek, binnen het programma CLICK.NL in 2013 tot stand is gekomen om de kennis over en innovatie in de creatieve industrie te versterken. De doelstelling van het project was om veranderingen in het werkveld van de architect ten gevolge van sociaal-maatschappelijke verschuivingen en de financií«le crisis te doorgronden en kansen voor de toekomst bloot te leggen.
Ik denk dat we daar uitstekend in geslaagd zijn. Ons consortium van De Zwarte Hond, EGM architecten, IAA Architecten, JHK Architecten, Rothuizen, Ballast Nedam, Havensteder en het Atelier Rijksbouwmeester is hierbij van onschatbare waarde gebleken. Twee keer per jaar werden onze bevindingen kritisch tegen het licht gehouden tijdens Living Lab bijeenkomsten, waarbij de consortiumleden op een zeer open wijze hun ervaringen hebben gedeeld over het aansturen van hun organisaties en de drijfveren om met ketenpartners samen te werken.
Daarnaast hebben de consortiumleden en verschillende branchegenoten hun organisatie opengesteld voor het verzamelen van gegevens. We hebben in lijn met de visie achter CLICK.NL - samenwerking tussen nieuwsgierige onderzoekers en ondernemende creatieve professionals - echt samen geïnvesteerd in kennis en innovatie voor een sterke economie en een duurzame samenleving. Ik heb dit als een zeer inspirerend en prettig proces ervaren. Ik ben er daarom van overtuigd dat we ook na de afronding van dit project blijven samenwerken om de innovatiekracht van de creatieve industrie te vergroten.
De architect als ondernemer was lange tijd een onderwerp waar weinig aandacht voor was in de bouw. Inmiddels is ondernemerschap in de architectenbranche een gangbaar begrip. Ook de BNA ontplooit veel activiteiten op dit gebied. We zijn als team uitermate trots dat onze promovendi Marina Bos-de Vos en Bente Lieftink, ieder vanuit hun eigen expertisegebied, met veel enthousiasme wetenschappelijke verdieping hebben gezocht in het woud aan interessante praktijkvoorbeelden en persoonlijke ervaringen. We hebben hierdoor zowel gedegen kennis kunnen vergaren op het gebied van het creí«ren en toe-eigenen van professionele, financií«le en gebruikswaarde, als inzicht gekregen in de verschillende rolstructuren in de bouwketen en het bestendigen van veranderingen hierin.
Ons onderzoek heeft geleid tot de ontwikkeling van deze ontwerpgids die zijn gebundeld in deze wetenschappelijke ontwerpgids voor het architectenbureau van de toekomst. Naast theoretische inzichten over het bureau en de samenwerking binnen een project wordt een onderscheid gemaakt in vier rolidentiteiten van waaruit de architect in de bouwketen kan acteren: de initiator, de specialist, de productontwikkelaar en de integrator. Het spelbord met kaartjes, dat als bijlage beschikbaar is bij deze publicatie, kan op verschillende manieren gebruikt worden om in gezamenlijkheid na te denken over waar je als bureau met een project heen wilt en welke verdienmodellen en manieren van samenwerken daar het beste bij past.
Per rolidentiteit worden de meest cruciale uitdagingen en kansen voor de bedrijfsvoering van architectenbureaus en de samenwerking in de keten weergegeven. Dit maakt het mogelijk om je rol in een project zelf te ontwerpen. Onze taak zit er hiermee op. Het is aan de lezer van het boek en gebruiker van het spel om de opgedane inzichten verder te vertalen in financieel en professioneel duurzame rollen voor de architect van de toekomst
Smart campus tools: Een verkenning bij Nederlandse universiteiten en lessen uit andere sectoren
Get PDFSinds we onderzoek doen naar het managen van universiteitscampussen is meer grip krijgen op het werkelijk ruimtegebruik — naast de (theoretische) bezetting en benutting die uit de roosters blijkt — een belangrijk thema. De match tussen vraag en aanbod van ruimte en faciliteiten kan nog veel scherper, vinden velen op de campus. Temeer omdat de vraag steeds dynamischer wordt, de gebruiker steeds veeleisender en het aanbod steeds duurzamer en kostenbewuster gemanaged moet worden. Met de technologische vooruitgang is het steeds beter mogelijk om te meten en te weten hoe gebruikers van de campus zich over de campus bewegen.
Dit was voor de Nederlandse universiteiten en hun facilitair/vastgoeddirecteuren (verenigd in het DFB netwerk) aanleiding om eind 2015 een onderzoeksopdracht te verstrekken, met als thema “Smart campus tools” voor het meten en verbeteren van ruimtegebruik. Doel van de opdracht was tweeledig: om te onderzoeken of/hoe de Nederlandse universiteiten anno 2016 “smart tools” inzetten en om te verkennen wat de nieuwste (technologische) ontwikkelingen zijn. Dit conceptrapport presenteert de resultaten van dit onderzoek.
Via deze weg willen we het DFB en alle personen die via interviews of enquíªtes hun medewerking verleenden, bedanken voor hun inspiratie, informatie en tijd. Met dit rapport hopen we de universiteiten verder te helpen bij het (nog) beter managen van hun campus en faciliteiten.
 
Menging maakt verschil: Hoe bewoners buurt- en wijkverandering ervaren en waarderen ondanks en dankzij herstructurering
Get PDFFor decades, the new housing estates that were built in the Netherlands after World War II had a solid reputation as neighbourhoods of progress (Reijndorp & Van der Ven 1994). Young households were queuing up for a dwelling in these modernist urban areas, which were known for an abundance of light, air and space, though only higher-skilled and white-collar workers could afford to live there. But with growing prosperity and rising expectations for housing quality, more well-to-do households moved into new residential areas. They were replaced by low-income households who from the end of the twentieth century on were also of migrant descent. The identity and reputation of many of these early post-war areas thus changed. Often labelled problem areas, they have been characterized as concentrations of joblessness, social deprivation, ethnic minorities, conflicting lifestyles, criminality and vandalism (Klijn & Koolma 1987; Ministerie van VROM 1997; Prak & Priemus 1985).
Neighbourhoods change. This is an inevitable and iterative process and it has many facets: ageing; economic, social and spatial development; and the perception of and subsequent reactions to these changes by residents as well as institutional actors like municipalities, housing associations, private landlords and other investors (Temkin & Rohe 1996). The accumulation of problems in post-war areas prompted urban renewal policies (Priemus 2004b; 2006) and intensive urban restructuring programmes throughout the Netherlands. A preliminary case study (Ouwehand & Davis 2004) revealed a positive evaluation of the interventions to improve these post-war neighbourhoods by demolition and new housing construction, often for owner-occupancy. But it also revealed a low level of neighbourhood satisfaction, which was attributed to a clash of incompatible lifestyles due to the large influx of new residents from lower-income groups, often households from one of the ethnic minority groups. According to the incumbent residents, these newcomers did not feel a personal bond with the neighbourhood and did not conform to the prevailing standards. Residents as well as other stakeholders urged further intervention.
That sketch of the problem led me to formulate the following research question for this doctoral dissertation: How do residents with different ways of life perceive and assess their changed and changing neighbourhood?
Three issues play a key role in this research. The first is the idea of ‘social mix’, a concept that dates back to the mid-nineteenth century (Sarkissian 1976) and has been pivotal to the debate about urban restructuring ever since Wilson published The Truly Disadvantaged (1987). It has prompted an abundance of scholarly research, though with divergent outcomes (Bond et al. 2011; Sautkina et al. 2012), and a rather polarized debate (Veldboer 2010). The second issue is that neighbourhood change occurs within the context of societal, economic and social change and is heavily influenced by urban and housing policies. Early post-war areas in the Netherlands are the product of housing policies implemented during the formation of the welfare state in the 1950s and 1960s (Van der Schaar 1987; Harloe 1995). These policies changed in the course of the following decades. Whereas the Dutch social housing system is not already residualized, sequential measures (Boelhouwer & Priemus 2014; Beuzenkamp et al. 2017) have reduced the volume of affordable social housing and increased the concentration of social housing in specific parts of the city, particularly the post-war areas (Hochstenbach & Musterd 2016; Zwiers et al. 2016). The third issue is that, since the beginning of the 1980s, neighbourhood change has been connected to the influx of new residents of migrant origin. These newcomers are often referred to as allochthones, as distinguished from autochthones, or native-Dutch residents423. In the Netherlands the debate about the integration of ethnic minorities started in the early 1990s, fuelled then by populist politicians like Fortuyn (assassinated in 2002) and nowadays by the anti-Islam politician Wilders. This debate continues to dominate the policy discourse. Discriminatory housing-allocation practices were fiercely opposed in the twentieth century. A proposal for unorthodox measures to avoid liveability problems, which were expected to arise from the predicted rapid growth in the share of allochthonous residents in parts of Rotterdam, led in 2003 to the Rotterdam Act. Under this legislation, vulnerable (a euphemism for allochthonous) newcomers could be prevented from obtaining a dwelling in specified areas of Rotterdam (Ouwehand & Doff 2013a).
The main aim of the present study is to unravel the two main drivers of neighbourhood satisfaction among residents with different ways of life. The first is an autonomous process: the influx of allochthonous newcomers in the neighbourhood as a result of moving processes. The second is a policy intervention to achieve social mix by demolition and new-built housing for owner-occupancy. I have selected the district of Zuidwijk in Rotterdam, one of the cases in a preliminary study, as the location of my research. Besides all the necessary ingredients, the district also has an interesting history and was the site of previous research on neighbourhood change. Building upon that basis, in 2008 we conducted 84 interviews with 116 persons in total, spread over three neighbourhoods in the district of Zuidwijk. The first is the Velden, half of which was slated for demolition, the other half predominantly designated for the elderly and further for single-family dwellings. The second is the Kampen, featuring renovated small single-family dwellings in the social rental sector. And the third is Burgen, featuring renovated single-family social rental, new-built single-family dwellings for owner-occupiers and new-built rental housing for the elderly. All the interviews were taped and transcribed and later coded and analysed using Atlas.ti. Seeking insight in the development of Zuidwijk, we held interviews with key persons as part of the preliminary research in 2003-2004 and with key persons in the housing association Vestia prior to the fieldwork in 2008 and in later years
Smart Energy Dissipation: Damped Outriggers for Tall Buildings under Strong Earthquakes
Get PDFThe use of outriggers in tall buildings is a common practice to reduce response under dynamic loading. Viscous dampers have been implemented between the outrigger and the perimeter columns, to reduce vibrations without increasing the stiffness of the structure. This damped outrigger concept has been implemented for reducing vibrations produced by strong winds. However, its behaviour under strong earthquakes has been not yet properly investigated. Strong earthquakes introduces larger amount of energy into the building’s structure, compared to moderate earthquakes or strong winds. In tall buildings, such seismic energy is dissipated by several mechanisms including bending deformation of the core, friction between structural and nonstructural components, and eventually, damage.
This research focuses on the capability of tall buildings equipped with damped outriggers to undergo large deformations without damage. In other words, when the ground motion increases due to strong earthquakes, the dampers can be assumed to be the main source of energy dissipation whilst the host structure displays an elastic behaviour. These investigations are based on the assessment of both the energy demands due to large-earthquake induced motion and the energy capacity of the system, i.e. the energy capacity of the main components, namely core, outriggers, perimeter columns and dampers. The objective of this research is to determine if the energy dissipated by hysteresis can be fully replaced by energy dissipated through the action of passive dampers.
This research is based on finite element (FE) models developed in Diana-FEA software. These analytical models consider the use of nonlinear settings throughout almost the whole FE model. The numerical investigations on passive damped outriggers are based on master Matlab scripts, which run combined parametric analysis within Diana.
Parametric analyses — Chapter 4
This chapter answers the question: Which parameters influence the distribution of seismic input energy through a tall building structure equipped with damped outriggers?
The numerical investigations focus on the aspects of the modelling and the structural parameters influencing the behaviour of tall building equipped with fixed and viscous damped outriggers. This chapter also provides a parametric study to assess the distribution of seismic energy in tall buildings equipped with viscous damped outriggers, i.e. with outriggers that have one or more viscous dampers installed between their ends and the perimeter columns. The aim of this explorative study is to determine which parameters influence (a) the structural response and (b) the distribution of seismic input energy through the building structure. First, this chapter describes a parametric study that addresses the influence of natural period of the building, position of the outriggers, damping coefficient, and stiffness coreto- outrigger and core-to-columns ratios in the control performance of the outrigger structures. Indirectly, it provides the basis for exploring which strategies will extend the elastic response threshold of a tall building equipped with viscous dampers and subjected to strong earthquake ground motions. The optimization of these parameters define pseudo-optimal configurations, which are further are assessed in terms of response reduction, namely displacement, acceleration, base shear, base moment and stress distribution; and, in terms of energy distributions. The strategy to assess the distribution of earthquake energy in tall buildings equipped with viscous damped outriggers and subjected to strong motions is based on the numerical study of 60-storey buildings equipped with conventional and damped outriggers, respectively. Secondly, this chapter describes the inter-dependency between structural properties of tall buildings equipped with damped outriggers and ground motion characteristics, which is examined under small, moderate, strong, and severe levels of the 1940 El Centro earthquake record.
Single passive damped outrigger system — Chapter 5
This chapter provides answers to the questions: How such energy is eventually dissipated by both the host structure and the viscous dampers? To which extent can hysteretic energy be completely overcome by the energy dissipated by the action of dampers?
The objective of the study presented in this chapter is to determine if the energy dissipated by hysteresis (damage) can be fully replaced by energy dissipated through the action of passive viscous dampers. More precisely, the goal is to determine whether it is correct to assume that main structural components will remain elastic during the entire strong earthquake response of a tall building, as well as which parameters mainly affect the response of damped outrigger structures and how such influence is exerted. In order to determine to which extent the use of viscously damped outriggers would avoid damage, both the host structure’s hysteretic behaviour and the dampers’ performance need to be evaluated in parallel. First, the time-history responses of fixed and damped outrigger structures, subjected to different levels of peak ground accelerations (PGA) of a suite of eight earthquake records, are obtained using 2D finite element (FE) models. Using these results, the nonlinear behaviour of the outrigger system with and without viscous dampers is examined under small, moderate, strong and severe long-period earthquakes to assess the hysteretic energy distribution through the core and outriggers. Next, the distribution of seismic energy in the structures is assessed by means of the damping-to-input (ED/EI), dampers’ dampingto- input (EDAMPERS/EI), and hysteretic-to-input (EH/EI) energy ratios; the concept of optimal configuration is therefore discussed in terms of reducing the hysteresis energy ratio of the structure. This assessment gives insights on which strategies will extend the elastic response threshold of a tall building equipped with viscous dampers and subjected to strong earthquake ground motions. The results show that, as the ground motion becomes stronger, viscous dampers effectively reduce the potential of damage in the structure if compared to conventional outriggers. However, the use of dampers cannot entirely prevent damage under critical excitations.
Double conventional and damped outrigger system — Chapter 6
This chapter answers the question: Which strategies will extend the elastic response threshold of a tall building equipped with viscous dampers and subjected to strong earthquake ground motions?
The use of a set of outriggers equipped with oil viscous dampers increases the damping ratio of tall buildings in about 6-10%, depending on the loading conditions. However, if a single damped outrigger structure is designed for an optimal damping ratio, could this ratio still be increased by the addition of another set of outriggers? Should this additional set be equipped with dampers too? In order to answer these questions, several double damped outrigger configurations for tall buildings are investigated and compared to an optimally designed single damped outrigger, located at elevation 0.7 of the total building’s height (h). Using free vibration analyses, double outrigger configurations increasing damping up to a ratio equal to the single-based optimal are identified. Next, selected configurations are subjected to small, moderate, strong, and severe earthquake levels of eight ground motions to compare their capability for dissipating energy and thus avoiding damage under critical excitations. Last, a simplified economic analysis highlights the advantages of each optimal configuration in terms of steel reinforcement savings versus damper cost. The results show that combining a damped outrigger at 0.5 h with a conventional outrigger at 0.7 h is more effective in reducing hysteretic energy ratios and economically viable if compared to a single damped outrigger solution.
Conclusions
From the parametric analyses using FE models with conventional and damped outrigger systems, under free vibration, it is concluded that optimal damping coefficient Cd and optimal location λ have a major influence in the optimal damping ratio ζ. This optimal damping ratio may not necessarily imply a significant reduction in the overall response of the outrigger structure. Nevertheless, when λ and Cd approximate to the optimal values, the effect of Ïctc may imply an overall ζ increase in 7%. This suggests that if required damper sizes are not available, a modification in the ratio Ïctc will help to increase the overall damping ratio. It should be noted that such increase occurs only if Ïctc decreases.
Complementary modification of the stiffness ratios may help to improve the effect of the viscous damped outriggers in the reduction of response of the building. For example, both λ and Ïctc exert their influence by modifying the building’s natural frequency. The fact that Ïcto does modifies the response but not the frequency, suggests that its influence is closely related to the effect of the viscous dampers. None of the parameters under discussion, namely λ, Ïctc and Ïcto, have any influence on the frequency shift of the damped outrigger, when λ<0.6. Frequency shifts become more significant as the outrigger approaches the roof.
From the numerical analyses under El Centro earthquake, it is concluded that when the outrigger is flexible (Ïcto =4), EI is comparatively large under all earthquake levels except by severe. This condition is not affected by the value of Ïctc. Under severe earthquakes, the use of a rigid outrigger (Ïcto =1) implies larger amount of input energy in the system. This shift may be the result of large damping forces being linearly amplified by the high velocities of the severe motions.
From all the parametric analyses, it is concluded that regardless the optimal Cd'λ < 0.4 has less effect on improving the overall damping ratio of the building, if compared to values of λ >= 0.4. This suggests that optimal λ is somewhere between 0.4 and 0.9. Nevertheless, the optimal damping varies with the mode, so no single outrigger location will lead to reduce the response of all the modes to its minimum.
From the numerical analyses using FE models with conventional and viscous damped outrigger systems, subjected to four levels of ground motions, it was concluded that as the ground motion becomes stronger, viscous dampers effectively reduce the potential of damage in the structure if compared to conventional outriggers. The results confirm that increasing dynamic stiffness by using dampers is more effective than simply increasing stiffness by adding outriggers to reduce the overall response of core structures. The use of dampers in the outrigger seems to be effective in reducing both kinetic and strain energies, which also explains the overall decrease in the accelerations.
In addition, the use of viscous damped outriggers under optimal design conditions, reduces the overturning moments and stresses of the main components of the system, i.e. core, outriggers and perimeter columns, under strong earthquakes —if compared to a conventional outrigger.
From the numerical analyses using FE models with conventional and viscous damped outrigger systems, subjected to four levels of ground motions, it was concluded that inter-storey drifts, peak accelerations and base shear are not substantially reduced with the addition of viscous dampers to the outriggers. These results reinforce the conclusion that no optimal configuration can be considered optimal for reducing all structural responses.
From the numerical analyses using FE models with conventional and damped outrigger systems, subjected to four levels of ground motions, it was concluded that damped outriggers cannot reduce completely the structural damage under critical earthquakes because the peak EH/EI usually precedes the peak Edampers/EI. On the other hand, since dampers increase the dissipative action of energy by damping, the energy that must be absorbed by hysteresis of the structure is reduced.
Hysteretic energy is concentrated in the core, whose damage is provoked by the overpass of the tensile strength. Hence, the core is the main dissipative source of both damping and hysteretic energy. With the addition of viscous dampers the outrigger has a minor load-bearing role. The main advantage of adding viscous dampers to the outriggers is the overall reduction of stress in the members, thus increasing ductility in the structure.
From the analyses of several configurations of double damped and combined fixed+damped outrigger systems described in Chapter 6, under free vibration, it is concluded that only a double set of damped outriggers and the combined damped and fixed outriggers (attaching viscous dampers in the lower set of outriggers) display larger increase of ζ than the 8% of the single damped outrigger. Optimized ζ of the former two are 8.8 and 8.6%, respectively.
Despite this increase of ζ, double and combined outrigger solutions do not present further reduction of peak inter-storey drifts when compared with the single configuration. This seems to suggest that configurations with optimal ζ might not be further optimized for inter-storey drifts reductions. From these results it is not possible to conclude which configuration seems to be the optimal to reduce the overall structural response.
From the analyses of optimal double set of damped outriggers and the combined damped and fixed outriggers, subjected to eight different ground motions, it is concluded that these configurations reduced the hysteretic energy ratio (EH/EI). In addition, the double damped outrigger is more effective for reducing the damage in the structure when subjected to strong and severe earthquake levels. However, such reduction in the hysteretic energy provided by the supplemental damping is not significant.
From all the time-history analyses using a set of eight earthquake records, it can be concluded that viscous damper outrigger structures exhibit a comparatively improved performance if the use of two outriggers matches the predominance of the 2nd mode of vibration, given by the ground motion frequency.
From the simplified economic analyses of optimal double set of damped outriggers and the combined damped and fixed outriggers, it is concluded that the extra costs due to the double damped are about 50% more expensive than the single damped solution. This is valid within the framework given by the Cd values involved in these optimal designs, and assuming the building costs mostly influenced by the amount of reinforcement steel and viscous dampers. To the contrary, the additional costs due to the combined damped and fixed solutions are about 16% cheaper than the single damped solution