In this thesis an investigation of the shear stiffness and capacity of joints between pre- fabricated concrete elements regarding to different material properties is reported. Two different models of shear key joints, connected to prefabricated walls, were cre- ated in the non-linear finite element software, ATENA 3D, with the aim to estimate a realistic behaviour of the joints regarding to the external loads.

A problem with the construction line of business versus the environment is that there are not that much knowledge and rules around the carbon dioxide emissions that several construction projects releases. A lot of companies that we contacted didn´t have the knowledge about the carbon dioxide that releases from the construction projects that they´ve built. This is understandable because it is a very difficult calculation to do, it requires very advanced tools and knowledge around the subject to make detailed calculations. With this master thesis, we want to compare prefabricated buildings with different materials from an environmental perspective with a focus on the carbon dioxide. The different materials we are comparing are steel and tree.   The purpose with this master thesis is to create a basis for Riki AB so that they will have a better sight on the environmental impact from their steel prefabrications which is shipped from China and this will be done with a comparison between a Swedish traditional half prefabricated apartment building.   The first step for the thesis has been a literature study and interviews about the subject. The obtained literature study consists of rapports, relatable thesis, analysis and digital internet sources. The interviews were implemented with companies which were knowledgeable of prefabrication and materials, this was done to get a deeper understanding of the materials effects of the environment.   The result of this examination results that the prefabricated apartment buildings made of steel from China has a larger carbon dioxide emission compared to the Swedish half prefabricated apartment buildings made of tree.

В настоящее время Китай еще не достиг наивысшего уровня развития сборно-монолитных зданий, обладающих высоким уровнем сборности. Поэтому исследования сборно-монолитного строительства актуальны. В работе представлен вариант совершенствования оценки сборно-монолитных зданий на примере китайского гражданского строительства. Кратко рассмотрена история развития сборно-монолитных зданий в Китае и других странах. Разработан алгоритм оценки сборно-монолитного здания, представлен пример практического применения методики и алгоритма. / At present, China has not yet reached the highest level of development of prefabricated monolithic buildings with a high level of prefabrication. Therefore, research into prefabricated monolithic construction is relevant. The paper presents an option for improving the assessment of prefabricated monolithic buildings using the example of Chinese civil engineering. The history of the development of prefabricated monolithic buildings in China and other countries is briefly reviewed. An algorithm for assessing a prefabricated monolithic building has been developed, and an example of the practical application of the methodology and algorithm is presented.

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This master thesis investigated the influence of prefabrication rate of buildings on the embodied environmental impacts. Through a comparative attributional LCA four different Swedish buildings were investigated to explore the influence of PR on the environmental impacts in the categories Cumulative Energy Demand, Global Warming Potential, Water Consumption, Fossil Resource Scarcity, and Mineral Resource Scarcity. The reference buildings had prefabricated rates of 14, 26, 38 and 91%. The results indicate that a higher prefabricated rate (PR) can lead to a lower impact in these categories to some extent; mainly due to a lower amount of total concrete material per square meter, dependent on the construction method used. The most influential materials in the comparison where cement and steel. An initial improvement of several impacts was seen when the PR of concrete buildings increased from 14% to 38%, with one reason being increased material efficiency of concrete. When further increasing PR, it is not certain that impacts necessarily continue to improve, as no clear difference was shown between the buildings with PR of 91% and 38%. This seems to point towards that any clear relationship between PR and the chosen impact categories breaks down or flattens out for higher prefabricated rates, and that the most beneficial solution often could be a semi-prefabricated construction method. This is concurrent with previous results in the current body of literature on LCA of construction and prefabricated rates. Instead, for additional reduction of environmental impacts after this point, other factors such as material choice and could become increasingly important. Additionally, the question of which impact category to prioritize arises. / Denna masteruppsats undersöker betydelsen av andelen prefabricerad betong i byggnader och dess påverkan på den inbyggda miljöpåverkan. En jämförande bokförings-LCA gjordes av fyra svenska referensbyggnader för att undersöka prefabrikationsgradens inverkan i fem kategorier av miljöpåverkan: kumulativ energiförbrukning, global uppvärmning, vattenförbrukning, och förbrukning av minerala och fossila naturresurser. Referensbyggnaderna hade prefabricerade andelar av 14, 26, 38 och 91%. Resultaten indikerar att en högre grad av prefabricering kan leda till en lägre påverkan i de undersökta kategorierna i viss mån, inte minst på grund av en lägre total förbrukning av betong per kvadratmeter BTA, beroende på vilken konstruktionsmetod som används. De mest betydelsefulla råmaterialen fanns vara cement och stål. En initial förbättring i flertalet kategorier syntes när prefabrikationsgraden ökade från 14 till 38%, mycket tack vare den lägre betongförbrukningen. När prefabrikationsgraden steg ytterligare till 91% syntes ingen tydlig förbättring, och det kan inte anses klarlagt att en högre prefabrikationsgrad nödvändigtvis har lägre miljöpåverkan. Detta indikerar att den mest fördelaktiga lösningen ofta kan vara en semi-prefabricerad lösning, vilket överensstämmer med resultaten i tidigare studier på området. För ytterligare reducering av miljöpåverkan efter en viss grad av prefabricering framstår andra faktorer såsom materialval som allt viktigare.

I denna studie görs en jämförelse av prefabricerade våtrumsmoduler gentemot platsbyggda våtrum ur ett ekonomiskt-, tids- och kvalitetsperspektiv. Detta arbete görs i samarbete med Gunnar Prefab AB där en undersökning görs baserat på 300 fiktiva våtrum. Det huvudsakliga målet med detta arbete är att ta fram en kostnadskalkyl, en tidsplan och de kvalitetsmässiga aspekterna för metoderna. Detta i syftet om att ge en vägledning vid beslutsfattande om produktionsmetod vid framställning av våtrum. Jämförelsen baseras på en egenframtagen mängdförteckning och våtrummen granskas under godtyckliga förutsättningar i nyproduktion. Undersökningen har begränsats till en leverantör och en planlösning. Först tas en teoretisk referensram fram som är grundförutsättningarna för arbetet. I denna del sker en genomgång för hur tillverkningen av ett våtrum går till för respektive metod och teorin bakom framställningen av en kostnadskalkyl. Slutligen redovisas det hur tidsplanen och hur de kvalitetsmässiga aspekterna tas fram. I nästa kapitel redovisas tillvägagångssättet för beräkning av de direkta- och gemensamma kostnaderna samt genomförandet av jämförelsen i tid och kvalité. Det visade sig vara svårt att göra en kostnadsjämförelse baserat på ett så pass stort projekt som 300 badrum då övrig litteratur i ämnet visade på olika siffror i kostnadsfrågan. I jämförelse vad gäller kvalitén granskades metodernas kvalité- och ledningssystemen samt för- och nackdelarna ur kvalitésynpunkt. Detta resulterade i att kvalitén för det prefabricerade modulerna var något högre då enheterna tillverkas i kontrollerade förhållanden. Den största skillnaden mellan dessa byggmetoder var byggtiden. För det prefabricerade våtrummet tog det 34 veckor att framställa och för det platsbyggda tog det 102 veckor. Slutsatsen av arbetet är att det prefabricerade våtrummet produktionstekniskt blir det billigare alternativet endast om omfattning av projektet är tillräckligt stort, dock kan det vara ett bättre val ur ett kvalité- och tidsperspektiv. En rekommendation vid val av denna metod är att entreprenören behöver vara delaktig i ett tidigt skede för att minska byggtid och kostnad. Vid projekt med flera olika typbadrum rekommenderas att kombinera den prefabricerade metoden med den platsbyggda, då moduler inte går att implementera för exempelvis mindre WC. På grund av det höga trycket på marknaden kan det vara svårt att få tag på material och arbetskraft vilket kan leda till konsekvenser för slutresultatet. Vid pressade tids- och kostnadsförhållanden så kan prefabricerade moduler vara att föredra då de framställs i fabrik med en löpandebandprincip. / The premise of this thesis is a comparison study of which prefabricated bathroom modules are compared to on-site built bathrooms from an economic, time and quality standpoint. This work is done in collaboration with Gunnar Prefab AB where a survey is carried out based on 300 fictitious bathrooms. The main objective of this work is to develop a cost estimate, a timeline and the quality aspects for each method. The purpose is to provide guidance when choosing what production method is the most optimal choice when producing bathrooms. The comparison is based on a self-made quantity list and the bathrooms are examined under arbitrary conditions in new production. The survey has also been limited to one contractor and one specific architectural plan. The thesis starts off with a theoretical reference framework which is considered as the foundation of this report. In this chapter, an explanation is carried out on how the production of a bathroom is constructed for each method and the theory behind the production of a cost estimate. Lastly, an explanation is given on how the timeline and the quality aspects are developed throughout the project. The following subheading presents the approach of calculating direct and common costs and the implementation of the comparison in time and quality. It proved difficulties to make a cost comparison based on a project as large as 300 bathrooms do to that literature in this subject showed different figures revolving the cost issue. The result of collected quotes and cost calculations gives a total of 17 533 544 kronor for the prefabricated bathroom modules and 18 290 691 kronor for the built on-site bathrooms. To compare the quality and its advantages, disadvantages and quality- and management systems were examined from a quality point of view. The results concluded that the quality of the prefabricated modules was slightly better due to the fact that they were manufactured under a controlled environment. The main difference between said construction methods was the construction time. For the prefabricated bathrooms it took 34 weeks to produce and for the built on-site bathroom it took 102 weeks. The conclusion of this thesis is that the prefabricated bathroom could be the cheaper option only if the project would be of a larger scale and could be a better choice from a time-saving perspective. One recommendation when selecting this method is that the contractor needs to be involved from an early stage in order to reduce construction time and lower the costs. For projects with several different type of bathrooms where they have different layouts, it is recommended to combine the prefabricated method with the built on-site, as modules can’t be implemented for plans with smaller WC. Due to the high pressure on the market, it can be difficult to obtain materials and labour, which can lead to consequences for the end result. In projects where time and cost is of essence, the prefabricated modules may be preferable when produced in a factory that runs by the assembly line principle.

The inverted-T bridge system is a rapid bridge construction technique that consists of precast inverted-T girders placed adjacent to one another and covered with a cast-in-place deck. This system was first implemented in the U.S. by the Minnesota Department of Transportation (Mn/DOT). This research focuses on improving the constructability of the Mn/DOT system while maintaining the system's structural performance characteristics. To accomplish this goal, five sub-assemblage specimens were cast and tested in the structures laboratory at Virginia Tech. These tests focused on identifying an improved precast girder geometry and transverse sub-assemblage connection for this system. From this study it was found that all of the proposed specimens behaved adequately at service load and strength. From these results, it is recommended to further evaluate a specimen with a tapered profile and no physical connection between precast girders for use in a Virginia Department of Transportation bridge near Richmond, VA. / Master of Science

Yes / Finite element (FE) analysis of fiber-reinforced polymer (FRP) reinforced concrete beams cast in U-shaped ultra-high performance concrete (UHPC) permanent formworks is presented in this paper. Concrete damage plasticity (CDP) and FRP brittle damage models were used to simulate the damage behavior of concrete and FRP bars. The results of FE simulation are in good agreement with the experimental results. Furthermore, parametric studies were conducted to investigate the effect of concrete and UHPC strengths, yield strength of steel bars, elastic modulus of FRP bars, ultimate tensile strength of FRP bars, types of UHPC normal strength concrete (NSC) interface and thickness of UHPC under different reinforcement conditions. Flexural performances, in terms of cracking, yield, ultimate loads and corresponding deflections, failure mode, energy dissipation and ductility, were investigated. Traction-separation model was used to describe the bonding degradation and the maximum slip of two types of bonding interfaces (smooth surface and medium-rough surface). Both flexural capacity and resistance to deformation of composite beams are significantly improved by the utilization of hybrid FRP/steel reinforcement. The UHPC formwork can also delay the occurrence and development of cracks. By appropriately increasing the strength of UHPC or elastic modulus of FRP bar, the flexural capacity of composite beams is effectively improved. It is expected that the results presented in this paper can guide the design and construction of U-shaped UHPC permanent formwork-concrete composite beams reinforced with FRP bars.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008. / Introduction South Africa is currently experiencing a significant increase in infrastructure investment. Forecasts by BMI-BRSCU have shown that the building and construction industry is expected to grow considerably to 2010, before languishing slightly to 2015. This growth will be driven in particular by investment in non-residential building (41% growth) and construction (73% growth) activities. Even beyond 2015 however, the demand will still be high on the construction industry to provide infrastructure for South Africa’s growing population. South Africa is also facing a serious shortage of engineers, technicians and other skilled workers in the construction industry. This places high demands on designers and contractors to provide services and to realise projects in ever-reducing time periods and at less cost. These conditions have made it increasingly difficult to maintain the required quality of construction in an industry where mistakes can lead to disastrous consequences. Recent advances in structural materials, structural systems and the way in which projects are handled, now enables a new look at the possibilities of combining pre-fabrication with on site work. This method, known as Hybrid Concrete Construction (HCC), has the potential to revolutionize the South African construction industry if applied correctly. Local research into this technique is however required and it is the aim of this thesis to draw attention to this subject. Key Findings Hybrid Concrete Construction (HCC) can be applied to any structural project, it will however not necessarily be successful. A structure needs to be adapted from the very start to suit a particular construction method. This ensures that all the advantages of the selected construction method may be achieved. Adapting a structure to a different construction method requires a mutual understanding and commitment from all project participants, including the architect, engineer, contractor and client. HCC also requires a certain degree of repetition in a project to be financially viable. A theoretical cost exercise was performed where only the material and erection costs were considered. In this exercise, HCC was found to be slightly less expensive than other construction methods for the Office Building of more than 10 storeys. HCC was also found to be significantly faster than other construction methods for the Office Building of more than 3 storeys. The time calculation was however based on the simplified time estimates from one source. Because of HCC’s shorter estimated construction period, the client can expect to earn revenue from a much earlier date. This decreases the relative cost of a HCC project. This advantage, however, needs to be quantified for chosen South African projects. On-site safety is still an important issue with HCC projects. Labourers are not accustomed to this construction method and it may be necessary to alter current skill development programs to include a crane safety course. The training of qualified riggers and crane operators should receive priority if HCC is to develop in South Africa. This preliminary investigation has shown that Hybrid Concrete Construction (HCC) can be feasible for the South African market. Further investigation is however required to determine the parameters for which HCC would be the preferred construction method. Recommendations Based on the findings and conclusions of this investigation, the following recommendations are made. The following actions should be undertaken by individual South African companies: · Develop relationships with external project partners · Train competent riggers and crane operators The South African concrete industry should invest in the following actions: · Invest in mass-producing precast concrete facilities · Develop a central database of South African projects with information on time, costs, project concepts and layouts to be used as a guideline for decision making · Develop local guidelines for the production and application of self compacting concrete · Compile guidelines for the design and construction of HCC and precast concrete construction in South Africa · Develop a local hidden corbel type connection to its full potential