Composite confinement systems for RC column repair and construction under seismic loads: Concept, characterization and performance

This study aims at developing, characterizing and validating an integrated composite confinement system of conventional jackets for: (1) repair and retrofit of existing bridge columns; and (2) construction of new bridge columns, subjected to earthquake excitations. A new composite steel confinement jacket was proposed by combining a thin steel sheet and prestressing strands as a hybrid jacket, incorporating active and passive confining pressure on damaged RC columns. Both experimental and analytical studies were conducted to understand the performance and effectiveness of the proposed repair method. The experimental study involved two 1/2-scale lap-spliced deficient RC bridge columns originally tested to failure under reversed cyclic loading. The proposed jacket was designed and implemented to repair the damaged columns to achieve the required performance level after repair intervention for service and ultimate limit states. Experimental results indicated that both repaired columns exceeded the strength and ductility of their as-built columns. The stiffness of the second column designed for ultimate limit state was completely restored. Analytical studies and collapse analyses on the seismic performance of post-mainshock repaired bridges subjected to mainshock-aftershock sequences demonstrated the efficacy of the proposed technique under severe mainshock-severe aftershock attacks. Another new composite confinement system of a fiber reinforced polymer (FRP) sheet wrapped around a polyvinyl chloride (PVC) tube with energy dissipation medium in between was developed for new bridge columns construction. This composite system is essentially a FRP-confined concrete-filled PVC tube, featuring exceptional durability properties of PVC materials in addition to high strength of the FRP fabrics. Experimental tests under uniaxial compression and flexural loading were undertaken to establish the representative stress-strain behavior of confined concrete filled PVC tubes (CCFPT). Experimental studies clearly demonstrated that the CCFPT system outperforms conventional FRP jacket. The intermediate energy dissipation medium is critical to make the post-peak behavior more ductile. Analytical studies were conducted and equations were derived for the prediction of the ultimate strength and strain of a CCFPT system --Abstract, page iv

Shear repair methods for conventionally reinforced concrete girders and deep beams

Many conventionally reinforced concrete deck girder bridges (RCDG) and their intermediate supporting bent caps were designed during the Eisenhower interstate era of the 1950’s with the AASHO design equations at the time, which subsequently place higher demand on the concrete. The referenced components may exhibit diagonal cracking due to the initial design assumptions, increased traffic volume and truck weights, as well as temperature and shrinkage affects. Action is needed as these structures approach the end of their useful design life. Wholesale replacement is not economically feasible; therefore, repair may provide a more attractive alternative to maintain operational safety and freight mobility. The current research program builds on previous work at OSU, which focused on estimating unrepaired specimen capacity, to include various repair methods. The experimental program included full scale testing of specimens with vintage 1950s details, reinforcing steel, concrete strength/composition, and flexural cutoffs details. Repairs included externally applied steel stirrups, supplemental internal stirrups, externally applied carbon fiber reinforced plastic (CFRP), carbon fiber tape utilized in a near surface mount application, and longitudinal post tensioning (bent cap specimen only). All specimens were initially loaded under quasi-static force control to produce diagonal cracks in the specimen then repaired and tested to failure. Ultimate specimen capacity was compared against that predicted from those available in the literature (where applicable), international codes, sectional Modified Compression Field Theory (MCFT) analysis, Modified Zararis Mechanical Model (bent caps only), Strut-and-Tie methods (bent cap only), and nonlinear finite element analysis (NLFEM). Results indicate the repair methods increased the member strength and the predicted member strenths compare well to certain international codes, sectional MCFT analysis, and nonlinear FEM element analysis. Some repair techniques such as surface mounted CFRP produced disparate outcomes for different specimen types. The NSM repair technique requires additional research to draw general conclusions. Longitudinal post tensioning compared well with the Modified Zararis method. STM methods form a very conservative lower bound for design and are thus not suggested for base specimen capacity prediction in a retrofit analysis. Design recommendations for the deep beams are not provided, as there is not sufficient data to support general conclusions

Proceedings of the 9th fib International PhD Symposium in Civil Engineering : Karlsruhe Institute of Technology (KIT), 22 - 25 July 2012, Karlsruhe, Germany

The fib International PhD Symposium in Civil Engineering is an established event in the academic calendar of doctoral students. It is held under the patronage of the International Federation for Structural Concrete (fib), one of the main international associations that disseminates knowledge about concrete and concrete structures. The 9th fib International PhD Symposium was held at the Karlsruhe Institute of Technology (KIT), Germany, from July 22 to 25, 2012

Nonlinear and Time Dependent Analysis of a Concrete Bridge Suffering from Alkali-Silica Reaction: A Case Study of the Elgeseter Bridge in Trondheim.

This thesis reports a case study of the Elgeseter Bridge in Trondheim, which is known to suffer from Alkali-Silica reaction. The main aim is to provide more accurate predictions of the response and capacity of the bridge deck, beams and columns under loading according to håndbok 238 'Bruklassifisering', Norwegian Standards NS 3473 and due to ASR reaction which occurs in this construction. The objective is to form a basis for how ASR mechanisms determined through linear and nonlinear analysis can be used when assessing existing bridges. Concrete expansion due this reaction, the consequences and structural effects are presented. Changes due, to concrete cracking and reinforcement yielding are studied through finite element analyses of this bridge. Recommendations for nonlinear analysis of reinforced concrete slabs with shell and beam elements are established and verified with TNO Diana and SOFiSTiC software. Results from linear and non-linear analysis are verified by comparison with reports. Calculations showed lack of sufficient capacity to shear force and strengthen of the structure is necessary. What is more, this study describes how to use available nowadays methods to prevent the development of ASR reaction in this bridge. Finding relatively accurate solution requires selecting the appropriate methods, the best fitting methods have been considered and have been recommended

The comparative performance and behaviour of concrete elements containing glass-fibre reinforced plastic reinforcing bars.

Corrosion of steel reinforcement is a major concern in concrete construction, particularly in aggressive environments. Therefore corrosion resistant materials such as fibre composites are becoming increasingly feasible as an alternative concrete reinforcement. There are relatively few reported design guidelines for fibre composites in concrete.Hence, there is an urgent need for research and development to extend existing guidelines and standards such as those produced by the UK Institution of Structural Engineers and the ACI Committee (US), to encourage the wider use and acceptance of fibre composites as an alternative to steel in reinforced concrete elements.This investigation compares the behaviour and properties of a range of reinforced concrete beams under two point loading comprising different concrete grades and types using both steel and Glass Fibre Reinforced Plastic (GFRP) as primary and secondary reinforcement. A variety of conventional and 'novel' rebar configurations were used to assess their effect upon material efficiency and load capacity. Compressive and tensile strength and elastic moduli of all component properties were measured together with load, deflection, rebar and concrete strains on the reinforced concrete beams. Health and safety concepts through a risk assessment process were introduced for the testing at an early stage of the investigation.Principal measures of beam performance include the ultimate load capacity, stiffness and failure modes together with a 'performance quotient'; a mathematical expression derived as an efficiency comparator for beams of different types and composition. Photographic and video records were also used to monitor behaviour throughout. Experimental measurements generally showed good agreement with the corresponding theoretical, quasi-theoretical and design based values although the latter tended to overestimate the structural performance of the beams. In general, load capacity increased with increase in main rebar area but was affected to a lesser extent by concrete strength. The beams reinforced with steel had a greater load capacity than those reinforced with GFRP. However, GFRP reinforced beams generally displayed a greater capacity to absorb energy than steel but exhibited reduced stiffness at any given load although this was enhanced by the inclusion of glass fibres in the mix. Cracks in the GFRP reinforced beams were usually larger and deeper compared with those in the equivalent steel reinforced beams. Failure of the more lightly reinforced steel beams, including one GFRP beam, were predominantly in 'flexure'. The more heavily reinforced steel and the remainder of the GFRP reinforced beams exhibited mostly 'shear-bond' type failure. The 'novel' rebar geometry proved to be a simple, efficient and viable alternative to conventional rebar configurations in terms of load capacity and preferred mode of failure.It is suggested that further developments and applications could focus on small reinforced concrete elements such as lintels in aggressive environments and further refinement of the 'performance quotient' concept

International Conference on Civil Infrastructure and Construction (CIC 2020)

This is the proceedings of the CIC 2020 Conference, which was held under the patronage of His Excellency Sheikh Khalid bin Khalifa bin Abdulaziz Al Thani in Doha, Qatar from 2 to 5 February 2020. The goal of the conference was to provide a platform to discuss next-generation infrastructure and its construction among key players such as researchers, industry professionals and leaders, local government agencies, clients, construction contractors and policymakers. The conference gathered industry and academia to disseminate their research and field experiences in multiple areas of civil engineering. It was also a unique opportunity for companies and organizations to show the most recent advances in the field of civil infrastructure and construction. The conference covered a wide range of timely topics that address the needs of the construction industry all over the world and particularly in Qatar. All papers were peer reviewed by experts in their field and edited for publication. The conference accepted a total number of 127 papers submitted by authors from five different continents under the following four themes: Theme 1: Construction Management and Process Theme 2: Materials and Transportation Engineering Theme 3: Geotechnical, Environmental, and Geo-environmental Engineering Theme 4: Sustainability, Renovation, and Monitoring of Civil InfrastructureThe list of the Sponsors are listed at page 1

Acoustic and Elastic Waves: Recent Trends in Science and Engineering

The present Special Issue intends to explore new directions in the field of acoustics and ultrasonics. The interest includes, but is not limited to, the use of acoustic technology for condition monitoring of materials and structures. Topics of interest (among others): • Acoustic emission in materials and structures (without material limitation) • Innovative cases of ultrasonic inspection • Wave dispersion and waveguides • Monitoring of innovative materials • Seismic waves • Vibrations, damping and noise control • Combination of mechanical wave techniques with other types for structural health monitoring purposes. Experimental and numerical studies are welcome

Proceedings of the 9th International Conference on Civil Engineering

This open access book is a compilation of selected papers from the 9th International Conference on Civil Engineering (ICCE2022). The work focuses on novel research findings on seismic technology of civil engineering structures, High-tech construction materials, digitalization of civil engineering, urban underground space development. The contents make valuable contributions to academic researchers and engineers