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Adjacent voided slab bridges (AVSB) are economical systems for short spans. They provide the advantages of having low clearances due to their small section depths, accelerated construction times, and high torsional stiffness. The current longitudinal connection detail, a partial depth grouted shear key, has been known to fail in many of these bridges. The failure leads to reflective cracking in the wearing surface which allows chloride laden water to seep down through the joint, where it corrodes the reinforcement and prestressing strand. Ultimately, the failed keys lead to costly repairs and bridge replacements sooner than their proposed lifespan. This research project aimed to develop a more durable longitudinal connection detail by using sub-assemblages to test five alternate connections. The objective was to find a connection that abated all cracking in the shear key, thus removing the need for transverse post-tensioning. The tested connections employed alternate connection shapes and two different mix designs of fiber reinforced high strength concretes. The results showed that each tested connection outperformed the current detail. The findings of this research indicate that the longitudinal connection detail of adjacent member voided slab bridges should be modified. The modified version should be a blockout with lap splice connection detail utilizing a nonproprietary fiber reinforced high strength concrete. / Master of Science

Master of Science / Department of Architectural Engineering / Kimberly Waggle Kramer / Reinforced concrete slabs are one of the most common components in modern building construction. Reinforced concrete slabs with plastic voids slabs are a new and innovative type of structural, concrete slab system developed to allow for lighter self-weight of the structure while maintaining similar load carrying capacity of a solid slab. Plastic voided slabs are capable of reducing the amount of concrete necessary to construct a building by 30 percent or more. This reduction can be beneficial in terms of financial savings as well as building performance. This report examines a two-way, reinforced concrete slab with plastic voids construction in comparison to traditional flat plate reinforced concrete slab construction. The design process for plastic voided slabs is directly compared with traditional two-way flat plate reinforced concrete slabs through a design comparison of typical bays of 20’ by 20’ (6m by 6m), 25’ by 25’ (7.6m by 7.6m), 30’ by 30’ (9m by 9m) and 35’ by 35’ (10.7m by 10.7m). The traditional slab design process follows the ACI 318-11 Building Code Requirements for Structural Concrete chapter 13 Direct Design Method, while the plastic voided slab design process is modified from the BubbleDeck Design Guide for compliance with BCA using AS3600 and EC2. Sizes of traditional slab bays are compared to sizes of plastic voided slab bays. Results of the comparison study are presented.

Master of Science / Department of Architectural Engineering / Bill Zhang / In structural engineering, it can be challenging to incorporate a sustainable design without sacrificing structural integrity. However, flat plate voided slabs are an interesting alternative to standard flat plate concrete slab systems due to the reduction in concrete and the recycled plastic void formers that are located inside the slab. This research is necessary because an increased use of voided slabs in concrete structures would help fight climate change by reducing the CO₂ emissions caused from cement production. This report will discuss the advantages and disadvantages of implementing plastic void formers into solid flat plate slabs and examine a parametric study comparing voided flat plate slabs to solid flat plate slabs. The design of the voided slabs follows the CRSI Design Guide for Voided Concrete Slabs while also referencing the ACI 318-14 Building Code Requirements for Structural Concrete. Three different slabs for typical square bay sizes of 25 feet, 30 feet, and 35 feet are designed to compare the effectiveness of voided slabs to traditional solid slabs.

Betong är idag ett av de material som vi använder mest i byggbranschen och det har sinaföljder. Mer än 50 % av energiutsläppen från byggplatsen kommer från cementtillverkningen.Voided biaxial slab eller VBS är en revolutionerande teknik där man gjuter in plastbollar ibetongen tillsammans med armeringen. Arbetstiden samt torktiden kortas ned samtidigt somvi bevarar hållfastheten och dess funktionalitet. I den här rapporten kommer vi titta närmarepå VBS teknik och jämföra det med konventionell betongplatta och se om tekniken är lämpligför att implementeras i Sverige.Vi har använt oss av en kvalitativ metod i form av källanalys från internet och tryckta källor.Även en komparativ metod i de fallen vi har hittat information från mer än en källa.Rapporten kommer enbart fokusera på betongplattor och våningsavskiljande bjälklag. VBSanvänds i horisontella plan endast. Tak och väggar är därför uteslutna. Tekniken kommerpresenteras i form av viktiga aspekter för dess överlevnad i den svenska marknaden såsomekonomi, strukturella fördelar och hållbarhet.Resultatet visar att VBS rent ekonomiskt nästan bara är positivt jämfört med denkonventionella betongplattan som endast består av armerad betong. Konstruktionsmässigt ärVBS ett konkurrenskraftigt alternativ till armerad betong. Böjhållfastheten är detsamma somarmerad betong. Andra bra positiva aspekter är miljövänligheten, arbetsmiljömässigt,energikonsumtion och värmeisolering.De mindre bra egenskaperna är sämre prestanda i skjuvmotstånd, brandmotstånd ochljudisolering.VBS kan implementeras i Sverige men för att plast ska introduceras i en så pass stor skala såbehövs en infrastruktur. Den bör tillgodose hållbart produktion av Bubbledeck och separeramaterialen vid rivning. Tekniken medför stora fördelar men trots det kan företagen få svårt attmotivera sig till att bygga med VBS när betong är så lättillgängligt och varit med så länge. / Concrete is today one of the materials we use most in the construction industry and it has itsconsequences. More than 50% of the energy emissions from the construction site come fromcement production. Voided biaxial slab or VBS is a revolutionary technique in which plasticballs are cast into the concrete together with the reinforcement. The working time and thedrying time are reduced while maintaining the strength and its functionality. In this report, wewill take a closer look at VBS technology and compare it with conventional concrete slab andsee if the technology is suitable for implementation in Sweden.We have used a qualitative method in the form of source analysis from the Internet andprinted sources. Also a comparative method in cases where we have found information frommore than one source.The report will focus solely on concrete slabs and floor separating flooring. VBS is used inhorizontal planes only. Roofs and walls are therefore excluded. The technology will bepresented in the form of important aspects for its survival in the Swedish market such aseconomy, structural benefits and sustainability.The result shows that VBS is financially almost only positive compared to the conventionalconcrete slab, which consists only of reinforced concrete. In terms of design, VBS is acompetitive alternative to reinforced concrete. The flexural strength is the same as reinforcedconcrete. Other good positive aspects are environmental friendliness, work environment,energy consumption and heat insulation.The less good features are poor performance in shear resistance, fire resistance and soundinsulation.VBS can be implemented in Sweden but for plastic to be introduced on such a large scale, aninfrastructure is needed. It should meet the sustainable production of Bubbledeck and separatethe materials during demolition. The technology brings great benefits, but despite this,companies can find it difficult to motivate them to build with VBS when concrete is so easilyaccessible and has been around for so long.