Published Article / Hardly could projects be executed in Nigeria without alteration of design. This cannot be dissociated from designs which are not practically buildable or arising from changing taste of client. A study on factors influencing the buildability of designs in Nigerian construction industry was carried out to determine these factors and develop strategy to mitigate them. A total of one hundred (100) questionnaires were administered by the means of convenience and eighty six (86) was retrieved from a target population comprising; Architects, Builders, Engineers and Quantity Surveyors. The central tendency statistical tool was used for the analysis of data. The result of data analysis indicated that, clients briefing is an important factor for buildability of design. Among the influencing factors on buildability, complexity of the project followed by professional knowledge about construction ranks first and second and lastly cost economic value with no influence. On the current practice of buildability in Nigeria, the study revealed that Architects are mainly involved at the briefing stage to the award stages. While at the construction stage the Builder/Constructor features prominently at the various phases of construction. The study recommended the integration of Builder/Constructor at the early stage of building design.

Interfaces, joints and connections between different elements or sections cause more problems than most of the rest of the building. There are challenges during design, manufacture and construction as well as implications throughout the life of the building. These challenges are particularly relevant for the building envelope. Here the joints must perform at the same level as the main areas of wall or roof, but the pressures on them are invariably much greater. They must keep out the weather but, at the same time, accommodate tolerances. and inaccuracies and cater for movements both during construction and for as long as the building lasts. Managing construction interfaces is an important part of delivering a construction project without time delays or cost additions. However the lack of written publications on how to manage interfaces within construction is a problem discovered by the author very early in the research. Therefore the main aim of the research was; to improve the management of interfaces within the construction industry, with particular reference to interfaces within the building facade. The research was based on an EPSRC funded project entitled CladdISS "A standardised strategy for window and cladding interfaces". The methodology included industrial workshops, interviews, regular steering group meetings and a questionnaire. The strategy proposed to increase productivity, quality, reduce waste and reduce costs in design, manufacture, installation, and the building life cycle. The research highlighted a wide range of interrelated problems. However, the two main issues were: Poor communication between the design team and specialist contractors and poor interface detailing. The following situations typically exist: The interface responsibility is assigned too late if at all; the term 'by others' often leads to the interfaces being poorly managed; the design team does not have a good enough understanding of the construction and manufacturing tolerances of materials at the interfaces; often the design team does not have appropriate understanding of the cladding system they are designing; the specialist cladding contractors do not have enough input to the design of the cladding and interfaces early enough. Using the CladdISS strategy will enable the supply chain to be organised and provide a template for effective interface management.

As many tasks considering structural design in civil engineering become digitalised, the possibility of creating a more effective workflow increases. The development of computer programs that can handle large amounts of data and assist the decision making during design process increases the requirement of the data management to fully utilize the potential of a digital workflow. The design of reinforcement layout of concrete structures is time demanding and often performed manually. These characteristics of a workflow indicates that it may be suitable to be subject to automation. The aim of this thesis is to highlight the potential and the difficulties of using automated design procedures in civil engineering with focus on reinforcement layout design. Specifically, the selection of straight rebars and their placement within concrete structures has been studied with respect to buildability and the amount of reinforcement used. A computer program has been developed to select rebar diameters and arrangement, satisfying the required amount of reinforcement as well as some of the rules according to the Eurocode standard. In order to find feasible solutions, an optimization of the amount of reinforcement as well as different measures of buildability is performed, using a genetic algorithm. The result from two case studies showed that the program managed to perform tasks similar to an engineer and create design solutions which reduced the amount of reinforcement and the number of rebar types. Furthermore, it was shown that consideration to the identified buildability parameters played an important role in finding an optimal solution. The findings indicate that the design of reinforcement layout may be automated and that a more effective workflow can be achieved. / I takt med att fler delar av projekteringen av anläggningskonstruktioner blir digitaliserade ökar möjligheterna för att effektivisera arbetet. Utvecklandet av datorprogram som kan hantera mycket information och ge stöd till beslutsfattande ställer också krav på hanterandet av denna data för att utnyttja den fulla potentialen av ett digitaliserat arbetsflöde. Arbetsprocessen vid armering av betongkonstruktioner är tidskrävande och utförs idag ofta helt eller delvis för hand. Sådana processer bär karaktärsdrag som tyder på att de är lämpade för automatisering. Målet med studien är att undersöka problematiken kring att automatisera arbetsprocesser vid projektering av anläggningskonstruktioner med inriktning på armering av betongkonstruktioner. Specifikt, så har valet av raka armeringsjärn och dess placering i betongkonstruktioner studerats med avseende på byggbarhet och armeringsmängder. Ett datorprogram har utvecklats för att välja armeringsjärn och dess placering för ett givet behov och ett antal krav som ställs enligt Eurokod. För att hitta en möjlig lösning är problemet formulerat som en optimering av armeringsmängd och olika mått på byggbarhet. Optimeringen genomfördes med en genetisk algoritm. Resultatet från två fallstudier visar att programmet lyckades genomföra konstruktörens arbetsuppgifter och skapa lösningar som minskade mängden använd armering och antalet olika typer av armeringsjärn samtidigt som de identifierade måtten på byggbarhet främjades. Vidare visade resultatet att de identifierade byggbarhetsparametrarna spelade en viktig roll för att finna en optimal lösning. Detta indikerar att det är möjligt att automatisera denna process och att ett effektivare arbetsflöde kan erhållas.

Nowadays, construction industry is rapidly moving towards digitalization and automation that should enable increased rates and efficiency of construction processes, as well as higher possibilities for customization and architectural freedom. Among all technologies under development, digital fabrication with concrete by means of layered extrusion appears to be one of the most promising for purposes of fast mass housing construction. It enables formwork-free production of structures via layer-by-layer concrete printing. Freedom from formwork potentially makes the construction process more cost- and time-saving, but poses multiple challenges to mix design and test methods, especially in terms of concrete rheology. A special focus must be put on the structural build-up of concrete at rest, which is related to its buildability, i.e. capacity of the material to retain the shape of the extruded layers under their own weight and the weight of the subsequently placed layers. This research investigates into the structural build-up of cementitious materials, i.e. evolution of their strength and deformation properties over time at rest, and includes development and refinement of methodology to assess the structural build-up, as well as its modelling and prediction. With respect to methodology, major attention was directed to the constant rotational velocity (CRV) test used for evaluation of the static yield stress development, and rationalization of its application under field conditions. Based on a large amount of experiments performed with two rheometers of different design, characteristic curves and points describing patterns in behaviour of cementitious materials during a CRV test were established. The experimental study also dealt with assessing the effects of alterations in main elements of the CRV test protocol, such as test approach (single- versus multi-batch), pre-shear regime, applied CRV, on the test results. Possible errors in CRV tests were addressed and methods to improve the procedures of testing and data evaluation were suggested. In particular, the single-batch approach was enhanced by implementation of the developed breaking criterion, a concept of zero measurement for non-pre-sheared samples was introduced, and a method for simplified evaluation of elasticity by a single-head rheometer was proposed. General methodological recommendations on the design of a CRV test protocol were formulated. The results are applicable for various cementitious materials and not limited to concretes for layered extrusion. Furthermore, test methods for assessing the structural build-up of printable concretes were studied in terms of their applicability under field conditions, potential for automation, descriptiveness of obtained data and efficiency in predicting the buildability of printed concrete structures. The methods under investigation included CRV test, unconfined uniaxial compression test (UUCT), fast penetration test and newly proposed confined uniaxial compression test (CUCT); all tests were performed on extruded samples of eight printable concrete mixtures with various compositions and rheological properties. The corresponding results were juxtaposed in order to establish correlations between the data and compared to the results of buildability tests, in which hollow cylindrical structures were produced using a laboratory-scale 3D printer. The developed methodology was further used to conduct an in-depth investigation into the influence of aggregates on the structural build-up of ordinary concrete. In the experimental program, the binder composition was kept constant while the aggregate was varied in terms of the volume fraction and the surface area (per unit volume of concrete); the main focus was put on compositions with elevated aggregate content (45−55 % by volume). A mechanism lying behind the effects of the aggregate properties on the structural build-up of concrete was discovered by studying the structure of constitutive paste in concrete. Aggregate-induced inhomogeneity of constitutive paste allowed to introduce a three-component model of fresh concrete. Furthermore, to find models capable of predicting the parameters of structural build-up of concrete, i.e. static yield stress and structuration rate, concrete was viewed as a suspension of aggregate particles in suspending medium. Three approaches were employed to define the correspondent components. Suspending medium was represented by plain cement paste, screened cement paste and fine mortar considered as a part of concrete comprising particles below 0.5 mm; a substantiation for such a definition was provided. Applicability and limitations of the models based on all three approaches were compared. The modelling approach was further extended to printable concretes with nearly identical aggregate compositions, but different properties of paste. Opportunities and challenges in modelling the structural build-up of printable concrete, including the problem of material dependency of the models and the relevancy of fitting coefficients, were discussed. A modified Chateau-Ovarlez-Trung model based on the definition of suspending medium as fine mortar was acknowledged as best suited to describe the structural build-up of both ordinary and printable concrete.

Topics on the environment and sustainability attracts ever more attention today, especially in the construction sector. In Sweden, the building- and housing industry answers for a significant share of the total energy consumption, waste production and greenhouse gas emissions. The construction sector is often depicted as conservative with a low rate of productivity and innovation. Sweden’s National Board of Housing, Building and Planning suggests that errors and damages in construction causes expenses corresponding to tens of thousands new housing units each year in Sweden. In a time of climate action and pursuit of more circularity in resource use this issue becomes a burning question. There is no doubt that the industry has adopted the increasing awareness on sustainability issues. Carbon emission levels and renewable energy is being measured as any other key performance indicator. The strive for increased sustainability in construction becomes relevant for any actor who wants to remain relevant on the market. Considering recent studies emphasizing errors, damages, and inadequacies in construction a relevant question to ask would be if the reality lives up to the ambitions of a sustainable building industry. This study investigates underlying factors causing errors and damages in construction. Development on sustainability matters is plotted in relation to how it has affected the industry. Chosen literature covers sustainability development, building errors and damages as well as complexity matters unique for the construction industry. The study’s literature review is balanced by multiple interviews and a survey conducted with industry working professionals. The results suggest that the development of errors and damages in construction has been stable in recent years. However, data collection thru interviews and surveys declares that most participants has experienced an increase in errors and damages. The distribution of information and knowledge regarding errors and damages in construction has increased, which may have caused a perceived increase of errors and damages. Whether increased focus on sustainability matters has affected the occurrence of errors and damages depends on which time span is being considered. Sustainability related adaptions of work methods and materials may give rise to errors and damages in the short term. Hence, the heightened sustainability focus together with a rapid development pace calls for caution when designing buildings. The study’s data collection suggests an increasing lack of competence regarding the design of buildings and contract documents. Ambiguous and more demanding requirements together with lack of general liability and competence supply is described as the most urgent issues affecting errors, damages, and deficiencies in construction. / Frågor som berör miljö- och hållbarhet får allt mer uppmärksamhet i samhället, inte minst inom byggsektorn. I Sverige står bygg- och fastighetssektorn för en betydande andel av landets totala energianvändning, avfallsproduktion och utsläpp av växthusgaser. Byggsektorn beskrivs traditionellt som konservativ och beskylls ofta för att ha en låg produktivitetsutveckling och innovationsgrad. Boverket hävdar att fel, skador och brister i byggandet orsakar kostnader motsvarande ett produktionsbortfall på tiotusentals bostäder i Sverige varje år. I en tid av klimatomställningar och strävan mot ett mer cirkulärt användande av naturresurser blir denna fråga ytterst relevant. Att branschens aktörer tagit till sig det ökande hålbarhetsfokuset råder det inga tvivel om. Företags koldioxidutsläpp och andel förnybar energi är nyckeltal som deklareras i allt högre utsträckning. Att bygga hållbart är en självklarhet för vilken aktör som helst som vill behålla sin position på marknaden. Med bakgrund i de studier som lyfter fram fel, skador och brister inom byggandet är det relevant att fråga sig ifall verkligheten lever upp till ambitionen om det hållbara byggandet. Denna studie undersöker bakomliggande orsaker till att det uppstår fel och skador i byggandet. Branschens utveckling kopplat till hållbarhetsfrågan kartläggs i syfte att identifiera hur den påverkat byggandet. Den litteratur som studerats berör hållbarhetsutveckling, byggfel och byggskadorsamt den komplexitet som ofta är unik för byggbranschen. Genom intervjuer med tjänstemän samt en enkätstudie med yrkesarbetare ges en verklighetsanknytning och avstämning mot aktuell litteratur. Studiens resultat påvisar att utvecklingen av byggfel och byggskador varit oförändrad i närtid. Inom ramen för studiens datainsamling uppger majoriteten av de tillfrågade att de upplevt en ökning av fel och skador. Samtidigt har information och spridning av upptäckta fel och skador i byggandet ökat, vilket i sig kan ha föranlett en upplevd ökning. Huruvida det ökade hållbarhetsfokuset inom byggsektorn har påverkat förekomsten av byggfel och byggskador beror på vilken tidshorisont som beaktas. Hållbarhetsrelaterade omställningar av arbetsmetoder och material riskerar att ge upphov till fel och skador på kort sikt. Med ökat fokus på hållbarhetsfrågor och snabb utveckling ökar behovet av att kunna se den långsiktiga hållbarheten vid valet av byggtekniska lösningar. Studiens datainsamling pekar på ökande kompetensbrist i fråga om byggnaders och byggbeskrivningars utformning. Tvetydiga och mer omfattande kravställningar i kombination med bristande helhetsansvar och kompetensförsörjning beskrivs som de största riskfaktorerna i fråga om fel, skador och brister i byggandet.