An analytical investigation was conducted to study the behavior of a bottom flange bearing beam-to girder connection subjected to patch loading. This connection would be useful with deep deck (thickness greater than 3 in.) composite slabs as well as with commonly used deck where floor-to-floor height needs to be minimized. Five girder specimens were loaded until yielding during the initial phase of the research. The analysis section consists of the yield line theory and finite element study that were used to develop a model to predict the collapse loads of the girder sections. These results from the model were then compared to the experimental loads. A design procedure utilizing the proposed model and future work recommendations are then presented. / Master of Science

Este trabalho apresenta uma associação dos cálculos elástico e plástico, para lajes retangulares com carga uniforme e uma borda livre. O cálculo elástico é usado para pré-dimensionamento, na determinação dos momentos negativos e da razão dos momentos positivos nas duas direções. Esses momentos fletores são obtidos através de funções aproximadoras, determinadas a partir de tabelas. Após compatibilização dos momentos elásticos, são adotados os momentos de plastificação negativos, sendo os positivos obtidos através da teoria das chameiras plásticas, que é utilizada também no cálculo do comprimento das barras sobre os apoios. Conhecidas as armaduras, os momentos elásticos são novamente utilizados na verificação das flechas. Nos exemplos são comparadas as armaduras do cálculo elástico com as obtidas através do cálculo plástico, no qual se pôde constatar a economia deste último em relação ao primeiro. / This work presents an association of elastic and plastic analysis, for rectangular slabs with uniform load and a free edge. The elatic theory is used to estimate the negative moments and the relation between positive moments in the two directions. These bending moments are obtained from approached functions, based on tables. After compatibilization of elastic moments, the negative plastic moments are adopted and the positive moments are obtained from yield line theory, which will be used again in the calculation of the lenght of the bars over the supports. Once the reinforcements are known, the elastic moments are used again for checking the deflexions. In the examples, the results of elastic plate theory are compared with those obtained by plastic analysis, where it is possible to evidence the economy of the later over the former.

Throughout the United States accelerated bridge construction is becoming increasingly popular to meet growing transportation demands while keeping construction time and costs to a minimum. This research focuses on eliminating the need to form full-depth concrete bridge deck overhangs, accelerating the construction of concrete bridge decks, by using full-depth precast prestressed concrete deck panels. Full-depth precast overhang panels in combination with cast-in-place (CIP) reinforced concrete are experimentally and analytically investigated to assess the structural performance. Experimental loaddeformation behavior for factored AASHTO LRFD design load limits is examined followed by the collapse capacity of the panel-to-panel seam that exists in the system. Adequate strength and stiffness of the proposed full-depth panels deem the design safe for implementation for the Rock Creek Bridge in Fort Worth, Texas. New failure theories are derived for interior and exterior bridge deck spans as present code-based predictions provide poor estimates of the ultimate capacity. A compound shear-flexure failure occurs at interior bays between the CIP topping and stay-in-place (SIP) panel. Overhang failure loads are characterized as a mixed failure of flexure on the loaded panel and shear at the panel-to-panel seam. Based on these results design recommendations are presented to optimize the reinforcing steel layout used in concrete bridge decks.

Este trabalho apresenta uma associação dos cálculos elástico e plástico, para lajes retangulares com carga uniforme e uma borda livre. O cálculo elástico é usado para pré-dimensionamento, na determinação dos momentos negativos e da razão dos momentos positivos nas duas direções. Esses momentos fletores são obtidos através de funções aproximadoras, determinadas a partir de tabelas. Após compatibilização dos momentos elásticos, são adotados os momentos de plastificação negativos, sendo os positivos obtidos através da teoria das chameiras plásticas, que é utilizada também no cálculo do comprimento das barras sobre os apoios. Conhecidas as armaduras, os momentos elásticos são novamente utilizados na verificação das flechas. Nos exemplos são comparadas as armaduras do cálculo elástico com as obtidas através do cálculo plástico, no qual se pôde constatar a economia deste último em relação ao primeiro. / This work presents an association of elastic and plastic analysis, for rectangular slabs with uniform load and a free edge. The elatic theory is used to estimate the negative moments and the relation between positive moments in the two directions. These bending moments are obtained from approached functions, based on tables. After compatibilization of elastic moments, the negative plastic moments are adopted and the positive moments are obtained from yield line theory, which will be used again in the calculation of the lenght of the bars over the supports. Once the reinforcements are known, the elastic moments are used again for checking the deflexions. In the examples, the results of elastic plate theory are compared with those obtained by plastic analysis, where it is possible to evidence the economy of the later over the former.

Στόχος της παρούσας διατριβής είναι η διερεύνηση της αποτελεσματικότητας της ενίσχυσης στοιχείων τύπου πλάκας μέσω ενός νέου σύνθετου υλικού. Το νέο αυτό σύνθετο υλικό συντίθενται από ινοπλέγματα δύο διευθύνσεων σε ανόργανη μήτρα. Τα ινοπλέγματα αποτελούνται από ίνες άνθρακα ή ίνες υάλου, ενώ η ανόργανη μήτρα αποτελείται από κονίαμα. Ο όρος που έχει προταθεί από συγγραφείς για το νέο αυτό υλικό είναι Textile Reinforced Concrete, που στην Ελληνική γλώσσα θα μπορούσε να αποδοθεί ως Ινοπλέγματα Ανόργανης Μήτρας (ΙΑΜ). Για τον λόγο αυτό, παρασκευάσθηκαν δοκίμια τύπου πλάκας επί τεσσάρων περιμετρικών δοκών. Συνολικά κατασκευάσθηκαν τέσσερα δοκίμια τύπου πλάκας, εκ των οποίων τρία ενισχύθηκαν μέσω ΙΑΜ και ένα ήταν το δοκίμιο αναφοράς. Τα δύο δοκίμια ενισχύθηκαν με μία και δύο στρώσεις πλεγμάτων συνεχών ινών από άνθρακα, ενώ το τρίτο ενισχύθηκε μέσω εφαρμογής τριών στρώσεων πλεγμάτων συνεχών ινών υάλου. Τονίζεται πως τρεις στρώσεις πλέγματος συνεχών ινών υάλου έχουν ισοδύναμη δυστένεια με μία στρώση πλέγματος συνεχών ινών από άνθρακα. Στο πρώτο κεφάλαιο παρουσιάζονται οι ιδιότητες των ινών και της ανόργανης μήτρας, καθώς επίσης και η μηχανική συμπεριφορά του σύνθετου υλικού. Τέλος, γίνεται μια ανασκόπηση της έρευνας που έχει διεξαχθεί στο Εργαστήριο Μηχανικής και Τεχνολογίας των Υλικών, γύρω από το πεδίο των ενισχύσεων μέσω ΙΑΜ στοιχείων από οπλισμένο σκυρόδεμα. Στο δεύτερο κεφάλαιο συνοψίζονται οι ήδη υπάρχουσες τεχνικές επισκευής και ενίσχυσης πλακών. Επίσης, αναφέρονται παραδείγματα ενισχύσεων στοιχείων τύπου πλάκας από την διεθνή βιβλιογραφία. Στο τρίτο κεφάλαιο περιγράφονται οι εργασίες που πραγματοποιηθήκαν προκειμένου να κατασκευασθούν τα δοκίμια. Το κεφάλαιο αυτό χωρίζεται σε τέσσερις βασικές ενότητες. Στην πρώτη ενότητα παρουσιάζονται οι μηχανικές ιδιότητες των υλικών που χρησιμοποιήθηκαν για την παρασκευή και ενίσχυση των δοκιμίων, καθώς και οι διαδικασίες μέσω των οποίων αυτές διακριβώθηκαν. Στην δεύτερη και τρίτη ενότητα, αναφέρονται οι εργασίες που διενεργήθηκαν κατά την φάση της σκυροδέτησης και της ενίσχυσης αντίστοιχα των δοκιμίων, ενώ στην τέταρτη ενότητα αναλύεται η πειραματική διαδικασία που ακολουθήθηκε. Στο τέταρτο κεφάλαιο παρουσιάζονται τα αποτελέσματα που προέκυψαν από την διεξαγωγή των πειραμάτων. Το κεφάλαιο αυτό χωρίζεται σε τρεις ενότητες. Στην πρώτη ενότητα περιγράφεται η συμπεριφορά κάθε δοκιμίου ξεχωριστά. Στην δεύτερη ενότητα γίνεται σύγκριση των αποτελεσμάτων που εξήχθησαν για όλα τα δοκίμια, ενώ στην τρίτη και τελευταία ενότητα παρουσιάζονται εν συντομία τα βασικότερα συμπεράσματα, που προέκυψαν από την πειραματική διαδικασία. Στο πέμπτο κεφάλαιο, παρουσιάζονται οι βασικές σχέσεις μέσω των οποίων μπορεί να εκτιμηθεί το φορτίο αστοχίας πλακών δύο διευθύνσεων ενισχυμένων μέσω ΙΑΜ. Για τον λόγο αυτό δίνονται προσομοιώματα και σχέσεις, ενώ στην συνέχεια συγκρίνεται το φορτίο αστοχίας εκ των προτεινόμενων σχέσεων με το καταγραφόμενο φορτίο αστοχίας. Το έκτο και τελευταίο κεφάλαιο, παραθέτει συνοπτικά τα βασικότερα αποτελέσματα της παρούσας Διατριβής Διπλώματος Ειδίκευσης. Γενικά η νέα τεχνική ενίσχυσης, είναι ιδιαίτερα αποτελεσματική, αφού αυξάνεται σημαντικά το φορτίο αστοχίας των ενισχυμένων δοκιμίων συγκριτικά με το δοκίμιο αναφοράς. Παράλληλα η συμπεριφορά του πλέγματος είναι άριστη, αφού μέχρι και την στιγμή της αστοχίας δεν παρατηρείται αποκόλλησή του από την επιφάνεια του σκυροδέματος. Αξίζει να σημειωθεί πως η αστοχία των δοκιμίων συνέβη λόγω διάτρησης. Στο τέλος του κεφαλαίου αναφέρονται προτάσεις για μελλοντική έρευνα. / The aim of the present thesis is to investigate the efficiency of a new composite material for the strengthening of two way slabs. This new material is called “Textile Reinforced Concrete - (TRC)”. It comprises textiles, that is fabric meshes made of long woven, knitted or even unwoven fiber rovings in at least two orthogonal directions, impregnated with inorganic binders such as cement based mortars. For the purposes of this study, four specimens of two way slabs were produced. Three of them were strengthened with TRC, and the remaining specimen was kept as control. Two specimens were strengthened with one and two layers of textile respectively, whose yarns consisted of carbon fibers. The third one was strengthened with three layers of textile whose yarns consisted of glass fibers. It is worth mentioning that three layers of textiles with glass fibers, are equivalent in terms of stiffness and strength with one layer of textile with carbon fiber. The first chapter analyses the properties of fibers, yarns, textiles, and those of the inorganic matrix. The principles of the bond behavior are also presented. Moreover, the work done in the area of strengthening of concrete members at the faculty of Civil Engineering of the University of Patras is discussed. The second chapter summarizes the existing techniques of enhancement in strength of two way slabs. The purpose of the third chapter is to describe the course of action towards the construction of the specimens. The test procedure and measurements are also included in this chapter. The results as derived from the testing procedure are discussed in the fourth chapter of this dissertation. Comparisons of the results for each specimen are also drawn. In the fifth chapter, several experimentally and analytically based expressions have been used to evaluate the two-way capacity of slabs. The sixth chapter recapitulates the findings of the present research. It has been generally shown that the suggested technique appears to be effective. Noteworthy is the fact that all specimens experienced punching shear failure.

Baigiamajame magistro darbe nagrinėjami santvarinių konstrukcijų iš kvadratinių vamzdžių tiesioginio jungimo mazgų skaičiavimo ir konstravimo ypatumai. Analizuojama konstrukcinių elementų elgsena mazge ir jos sąlygojamas jungties irties pobūdis. Nagrinėjamos takumo linijos teorijos taikymo galimybės sudarant analitinius modelius. Pateikiami analitiniai modeliai, taikomi mazgų ašinės laikomosios galios skaičiavimo algoritmams sudaryti, pateikiamiems projektavimo norminiuose dokumentuose. Aprašomas mazgą sudarančių konstrukcinių elementų projektavimas pagal STR 2.05.08:2005 ir EN 1993-1-1 reikalavimus, bei mazgų ašinės laikomosios galios nustatymas pagal STR 2.05.08:2005 8-tą priedą, bei EN 1993-1-8. Darbe atlikta skaitinė projektavimo normose pateikiamų santvarinių konstrukcijų tiesioginio jungimo mazgų ašinės laikomosios galios nustatymo lyginamoji analizė. Suprojektuota santvarinė konstrukcija, kurios skaičiuojamoji schema parinkta tokia, kad būtų išanalizuoti visi projektavimo normose pateikiami tiesioginio jungimo mazgų tipai. Įrąžoms konstrukciniuose elementuose nustatyti pasinaudota kompiuterine skaičiavimo programa Staad.pro. Konstrukcinių elementų elgsenos mazge analizei pasinaudota kompiuterine programa CosmosWorks. Ištirta pagrindinių skaičiavimo algoritmuose pateikiamų rodiklių įtaka mazgo laikomąjai galiai. Norint parinkti santvaros konstrukcinius elementus ir nustatyti mazgų skaičiuotinę ašinę laikomąją galią bei atlikti skaitinę analizę buvo pasinaudota... [toliau žr. visą tekstą] / This master thesis considers design and estimation of truss joints between square hollow sections. Behaviuor of joints and its failure modes analyzed. The posibility to apply the yield line theory for analytical models considered. Analytical models used for determining the design capacity of the joint formulae in design guids presented. Truss members design following STR 2.05.08:2005 and EN 1993-1-1 and joint design capacity calculation following STR 2.05.08:2008 8-th annex and EN 1993-1-8 presented. It was made numerical convergence analysis between diferent design guidilines for estimating design capacity of the joint in this study. Truss structure designed, including all most commonly known joint types. Truss member loiding estimated using structural design and analysis software Staad.Pro. The behaviuor of the joint designed using finite element analysis software Cosmos.Works. Also the influence of governing joint parameters for the design capacity equations analysed. For truss structure design, capacity of the joint calculations and numerical analysis the calculation program was made using Microsoft Office Exel software.

Shotcrete (sprayed concrete) was used for the first time in 1914 and has become of  growing importance in stabilizing the excavated tunnel sections over the past century.  Even though the technology develops, there are some difficult tasks such as the design of a bolt anchored tunnel lining made of shotcrete. A proven and established design method does not exist today; instead the design of tunnel linings are based on trial and error or experience from similar projects. One method used today, to determine the actual structural behavior of fiber reinforced shotcrete, is the standard beam test method. Previous studies have shown that the beam method gives scattered results since the testing volume are relatively small and the fibers might be unevenly distributed.  In 1998, an alternative to determine the actual structural behavior of reinforced shotcrete was proposed, based on using round determinate panels. In 2004 this method became a part of the American Society for Testing and Materials, ASTM, standards. The method has the potential of becoming a major, reliable test procedure that better reproduce the behavior of reinforced shotcrete in situ, compared to test beams. An experimental test series was performed to compare the different testing methods in terms of data variability and validity, in the laboratory of Vattenfall in Älvkarleby. The experiment was performed on 30 specimens in total, with five different concrete recipes. The difference in the recipe was the fiber and cement content. The round panels are designed according to ASTM C-1550 and the beams according to SS-EN14488-3. The results from the experiment is here presented and evaluated, and also including the data variability and validity for the proposed method. The two basic testing methods of using beams and round panels are investigated, compared and evaluated, and their advantages and disadvantages discussed. / Sprutbetong användes första gången år 1914 och har under det gångna århundradet blivit allt viktigare för att stabilisera utsprängda tunnelsektioner. Trots att tekniken utvecklas finns det svårigheter med att exempelvis utforma bultförankrade tunnelbeklädnader av sprutbetong. En beprövad och etablerad metod att konstruera sprutbetongbeklädnad existerar inte idag. Istället används erfarenhetsåterföring från tidigare projekt och/eller experimentella försök. En testmetod som används idag för att återskapa beteendet hos sprutbetong är balkförsök. Tidigare studier har däremot visat att resultaten från försöken oftast har stor spridning vilket kan bero på att brottytorna är små areor där fibrerna kan vara ojämnt fördelade vilket påverkar resultaten. År 1998 föreslogs en alternativ metod för att fastställa de mekaniska egenskaperna hos sprutbetong, baserat på användning av runda plattor. År 2004 blev denna metod en del av the American Society for Testing and Materials, ASTM, standarder. Metoden har potential att bli en viktigt och tillförlitligt testmetod som mer realistiskt efterliknar beteendet hos fiberarmerad sprutbetong jämfört med balkprovning. En experimentell försöksserie har genomförts hos Vattenfall i Älvkarleby, för att jämföra de två metoderna med avseende på mätosäkerhet. Försöksserien är på totalt 30 prover, där fem olika betongrecept använts. Cementmängden och fiberhalten varierade mellan de olika recepten. De runda plattorna är utförda enligt ASTM C-1550 och balkarna enligt SS-EN14488-3. Resultaten från försöken har redovisats och utvärderats, och en mätosäkerhersanalys presenteras för metoden ASTM C-1550. Korrelationen mellan resultaten från de två metoderna är beräknad och varianskoefficienten presenteras. För- och nackdelar mellan båda testmetoderna diskuteras.