b) c) - Chalmers Publication Library (CPL)

1 Guidelines and Rules for Detailing of Reinforcement in concrete Structures A Compilation and Evaluation of Ambiguities in eurocode 2 Master of Science Thesis in the Master s Programme Structural Engineering and Building Technology ANNELI DAHLGREN LOUISE SVENSSON Department of Civil and Environmental Engineering Division of Structural Engineering concrete Structures Chalmers UNIVERSITY OF TECHNOLOGY G teborg, Sweden 2013 Master s Thesis 2013:142 a) h) d) g) f) e) c) b) MASTER S THESIS 2013:142 Guidelines and Rules for Detailing of Reinforcement in concrete Structures A Compilation and Evaluation of Ambiguities in eurocode 2 Master of Science Thesis in the Master s Programme Structural Engineering and Building Technology ANNELI DAHLGREN LOUISE SVENSSON Department of Civil and Environmental Engineering Division of Structural Engineering concrete Structures Chalmers UNIVERSITY OF TECHNOLOGY G teborg.

2 Sweden 2013 Guidelines and Rules for Detailing of Reinforcement in concrete Structures A Compilation and Evaluation of Ambiguities in eurocode 2 Master of Science Thesis in the Master s Programme Structural Engineering and Building Technology ANNELI DAHLGREN LOUISE SVENSSON ANNELI DAHLGREN & LOUISE SVENSSON, 2013 Examensarbete / Institutionen f r bygg- och milj teknik, Chalmers tekniska h gskola 2013:142 Department of Civil and Environmental Engineering Division of Structural Engineering concrete Structures Chalmers University of Technology SE-412 96 G teborg Sweden Telephone: + 46 (0)31-772 1000 Cover: Different configurations of links used as shear or torsional reinforcement in concrete structures.

3 Chalmers Reproservice G teborg, Sweden 2013 I Guidelines and Rules for Detailing of Reinforcement in concrete Structures A Compilation and Evaluation of Ambiguities in eurocode 2 Master of Science Thesis in the Master s Programme Structural Engineering and Building Technology ANNELI DAHLGREN LOUISE SVENSSON Department of Civil and Environmental Engineering Division of Structural Engineering concrete Structures Chalmers University of Technology ABSTRACT A proper detailing of reinforcement in concrete structures is very important with regard to structural behaviour, safety and good performance. However, rules in codes for detailing and minimum reinforcement ratios are not always easy to understand and interpret, since there is very limited or no background information explaining the function and providing motivations.

4 The aim of this project was to investigate and explain the background for the rules in the codes, especially eurocode 2, and give guidelines for good detailing, based on previous research and experience. Rules and guidelines for detailing of reinforcement that might be difficult to interpret or understand were identified by an initial study of the European Standard. From this study the background to some of the ambiguities were examined more thoroughly in a detailed literature study. An investigation consisting of interviews and a qualitative survey was performed in order to evaluate how structural engineers interprets and applies the rules provided in eurocode 2.

5 This was performed also with the intention to illuminate ambiguities to be able to suggest improvements of the new standard. The literature study showed that there is very limited background information to eurocode 2 and that it can be difficult to find answer, if something is perceived as unclear in the code. However, knowledge about the fundamental theory and required structural behaviour of reinforced concrete structures can be enough to understand many requirements, why this is provided in this report. The result from the investigation indicated that there are sections in eurocode 2 that can be difficult to interpret.

6 The standard needs to be improved or clarified in order to facilitate for the users and in order to know how to apply the rules on cases other than standard cases. Some of the identified problem areas in eurocode 2 are for instance lapping of longitudinal reinforcement, concrete frame corners subjected to opening moment and limitations of crack widths for concrete members subjected to shear and torsion. In some cases, specific changes of eurocode 2 have been suggested, while it in some cases is sufficient to add even stronger references between sections or include a short description of the motive for the intended rule, in order to improve the standard.

7 A need for further research has also been identified in order to be able to improve certain parts of eurocode 2. Key words: eurocode 2, EN 1992-1-1, Reinforcement, Reinforced concrete , Detailing II Riktlinjer och regler f r detaljutformning av armering i betongkonstruktioner En sammanst llning och utv rdering av oklarheter i Eurokod 2 Examensarbete inom mastersprogrammet Structural Engineering and Building Technology ANNELI DAHLGREN LOUISE SVENSSON Institutionen f r bygg- och milj teknik Avdelningen f r konstruktionsteknik Betongbyggnad Chalmers tekniska h gskola SAMMANFATTNING God detaljutformning av armering i betongkonstruktioner r v ldigt viktigt med h nsyn till s kerhet, funktion och verkningss tt.

8 Trots detta r regler f r detaljutformning och minimiarmering inte alltid s l tta att f rst och tolka eftersom det finns v ldigt begr nsad, om ens n gon, bakgrundsinformation som f rklarar funktionen och ger motiv f r reglerna. M let med projektet var att unders ka och f rklara bakgrunden f r reglerna i standarderna, s rskilt Eurokod 2, och ge riktlinjer f r god detaljutformning, baserad p tidigare forskning och erfarenhet Regler och riktlinjer f r detaljutformning av armering som kan vara sv ra att tolka eller f rst identifierades i en inledande studie av den europeiska standarden.

9 Utifr n denna studie utforskades d refter bakgrunden till n gra av sv righeterna i en mer ing ende litteraturstudie. En unders kning innefattande intervjuer och en kvalitativ enk tunders kning utf rdes f r att utreda hur konstrukt rer tolkar och till mpar regler som finns i Eurokod 2. Detta gjordes ocks med avsikten att ytterligare kunna belysa problemomr den och komma med f rslag till f rb ttringar av den nya standarden. Litteraturstudien visade p att det finns mycket begr nsad bakgrundsinformation till Eurokod 2 och att det kan vara sv rt att finna svar om n got uppfattas som oklart i normen.

10 Dock kan kunskap om grundl ggande teori och erforderligt verkningss tt hos armerade betongkonstruktioner r cka f r att f rst m nga av reglerna, varf r detta ges i denna rapport. Resultatet fr n unders kningen indikerar att det finns avsnitt i Eurokod 2 som kan vara sv ra att tolka. Standarden beh ver f rb ttras eller f rtydligas f r att underl tta f r dess anv ndare och f r att veta hur regler ska till mpas i situationer som inte medf r standardl sningar. N gra exempel p identifierade problemomr den i Eurokod 2 r omlottskarvning av l ngsg ende armering, ramh rn utsatta f r ppnande moment samt ber kning av sprickbredd f r betongelement som belastas av b de tv rkraft och vridning.