World Congress on Concrete Structures & Concrete Technology October 05-06, 2018 Los Angeles, California, USA

Biography:

Dr Zhaohui Huang is a reader in Civil Engineering at Brunel University London. He has involved in the teaching and research in structural engineering for more than 20 years. He is an international leading researcher in Structural Fire Engineering. He has published more than 100 refereed papers including 51 journal research papers. He has been awarded ASCE 2005 Raymond C. Reese Research Prize. He is one of the main developers of designer's version of VULCAN: a software which won two of the 2005 British Computer Society's Annual Awards.

Abstract:

In recent years, a robust finite-element software Vulcan has been developed for three-dimensional modelling of reinforced concrete structures under fire conditions. In this non-linear procedure a reinforced concrete building is modelled as an assembly of finite plain beam–column and slab elements, reinforcing steel bar elements and bond-link elements. Both material and geometric non-linearities are considered in the model. To consider the effects of concrete spalling on the thermal and structural behaviours of concrete structures in fire, a ‘void layer’ and ‘void segment’ are introduced to represent the spalled concrete part within concrete slabs, beams and columns. A critical temperature is used as the concrete spalling criterion. These developments enable the model to simulate quantitatively the effects of concrete spalling on both the thermal and structural behaviours of reinforced concrete structures in fire.  Under fire conditions, the formation of large cracks within reinforced concrete floor slabs may significantly reduce the fire resistance of buildings. For modelling integrity failure of reinforced concrete slabs in fire, a nonlinear hybrid FE model has been developed to predict the large cracks formed in RC floor slabs. The developed model was validated using the previous tested results. The nonlinear model developed can be used for assessing the integrity failure of the floor slabs in fire. Also a robust finite element procedure for modelling the localised fracture of reinforced concrete beams at elevated temperatures has been developed. An extended finite element method (XFEM) has been incorporated into the concrete elements in order to capture the localised cracks within the reinforced concrete beams

Biography:

The prediction of transient creep involves a lot of uncertainties due to its complex mechanisms of activation. Transient creep is seated in the cement paste and occurs due to hygrothermal conditions: water evaporation and CSH dehydration. Above 400ºC, it is accelerated by the aggregates geomechanical properties decay. There is also a thermal mismatch between aggregate expansion and cement paste shrinkage after 150ºC, leading to concrete microcracking. As a result, due to concrete complex behavior and the coupling effects of the different strain components (viscous+elastic+plastic+thermal) at high temperature, it is a very difficult task to uncouple the viscous strain component (creep) from other thermomechanical strain sources. In practice, transient creep can be described accurately enough by the concept of LITS (Load Induced Thermal Strains), which is defined as the difference between the total strain, measured on a preloaded specimen, and the free thermal strain, measured on an unloaded specimen, subtracting the initial elastic deformation at 20°C. In order to investigate transiente creep phenomenon in plain and fiber reinforced concrete structures, a new LITS semi-empirical model is proposed, recognizing concrete as a heterogeneous biphasic material (aggregates + matrix) and assuming that LITS is the sum of thermomechanical and thermochemical strain contributions. The semi-empirical model is compared with experimental tests performed on steel fiber reinforced concrete samples with 11-years-old. Moreover, a mesoscopic analysis was carried out in Abaqus in order to uncouple LITS strain contributions and highlight the effects of the boundary conditions, aggregates decomposition and concrete dehydration.

Abstract:

The prediction of transient creep involves a lot of uncertainties due to its complex mechanisms of activation. Transient creep is seated in the cement paste and occurs due to hygrothermal conditions: water evaporation and CSH dehydration. Above 400ºC, it is accelerated by the aggregates geomechanical properties decay. There is also a thermal mismatch between aggregate expansion and cement paste shrinkage after 150ºC, leading to concrete microcracking. As a result, due to concrete complex behavior and the coupling effects of the different strain components (viscous+elastic+plastic+thermal) at high temperature, it is a very difficult task to uncouple the viscous strain component (creep) from other thermomechanical strain sources. In practice, transient creep can be described accurately enough by the concept of LITS (Load Induced Thermal Strains), which is defined as the difference between the total strain, measured on a preloaded specimen, and the free thermal strain, measured on an unloaded specimen, subtracting the initial elastic deformation at 20°C. In order to investigate transiente creep phenomenon in plain and fiber reinforced concrete structures, a new LITS semi-empirical model is proposed, recognizing concrete as a heterogeneous biphasic material (aggregates + matrix) and assuming that LITS is the sum of thermomechanical and thermochemical strain contributions. The semi-empirical model is compared with experimental tests performed on steel fiber reinforced concrete samples with 11-years-old. Moreover, a mesoscopic analysis was carried out in Abaqus in order to uncouple LITS strain contributions and highlight the effects of the boundary conditions, aggregates decomposition and concrete dehydration

Biography:

Dr Arnaud Castel is an Associate Professor in the School of Civil and Environmental Engineering at the University of New South Wales, Australia. Arnaud Castel graduated with his PhD in 2000 at the University of Toulouse in France where he has carried out his early career before his relocation to UNSW Australia in 2012. He has co-authored/authored 150 publications, including 70 journal papers with a current scopus H-index of 21 and more than 1500 citations. Since his relocation to UNSW, A/Professor Arnaud Castel has secured over AU$1,500,000 research funds including ARC Discovery projects, ARC Linkage projects and  CRC projects

Abstract:

Geopolymer concrete (GC) is the result of the reaction of materials containing aluminosilicate such as fly ash and Ground Granulated Blast Furnace Slag with alkalis to produce an inorganic polymer binder. GC is Portland cement free low embodied carbon concrete. GC has been under intensive research around the world during the last 15 years. The major barriers to GC widespread adoption by the construction industry are concerns about durability and exclusion from current standards. Chemical reactions characterising alkali-activated binder systems differ drastically from conventional hydration process of Portland cement. Thus, the mechanisms by which concrete achieves potential durability are different between the two types of binders. As a result, testing methods and performance based requirements for geopolymer must be developed to be incorporated in a performance base standard. Testing methods presented will be looking at the risk of alkali leaching and efflorescence, passivity of reinforcement and chloride induced steel reinforcement corrosion in GC concrete.

Biography:

Samir Dirar is an internationally recognised expert in strengthening and repair of concrete structures. After receiving his PhD from the University of Cambridge, United Kingdom, he worked as Postdoctoral Researcher in Zienkiewicz Centre for Computational Engineering at Swansea University. He is currently a Senior Lecturer (Associate Professor) in Structural Engineering at the University of Birmingham with overall responsibility for the Structures Research Lab. He has published over 50 journal and conference publications and has been serving as Grant Reviewer for funding agencies as well as Member of ACI Committee 440-0F - FRP-Repair-Strengthening and ASTM International Committee D30 on Composite Materials

Abstract:

The strength enhancement of existing concrete infrastructure is an application of considerable economic importance. It has been estimated that the cost of replacing structurally deficient transport infrastructure in Europe, a significant amount of which are concrete structures, is about €400 billion. In the United States, thousands of concrete bridges have been rated as structurally deficient and $20.5 billion would need to be invested annually to eliminate the bridge deficient backlog by 2028. There is thus scope for safe, practical and economic strengthening techniques for existing concrete infrastructure. Extensive research has resulted in approved flexural strengthening methods for concrete structures. In contrast, shear strengthening of concrete members is a particular challenge due to the brittle nature of shear failure and the complex mechanics of the behaviour. The collapse of the de la Concorde Overpass in 2006 in Canada, which killed or injured eleven people, was a tragic reminder of the dire consequences of concrete shear failures. This Keynote Paper will critically review current concrete shear strengthening techniques, with a special focus on a promising method known as the deep embedment (DE), or embedded through-section (ETS), technique. The Keynote Paper will also highlight the experimental, numerical and analytical work on DE/ETS strengthening of concrete members carried out at the University of Birmingham. Topics will include development of bond models for reinforcement bars embedded into concrete, repair of corrosion-damaged beams, strengthening of large scale bridge girders, seismic strengthening of beam-column joints, nonlinear finite element modelling and development of design guidance

Biography:

Dr. Ying Huang obtained her Ph.D. from Missouri Univeristy of Science and Technology in 2012. Right after her Ph. D., Dr. Huang joined the department of Civil and Environmental Engineering at North Dakota State Univeristy as a faculty till now. Her research backgrounds are in smart cities and autonomous systems, smart materials and structural health monitoring, intelligent transportation systems, pavement and traffic monitoring, pipeline corrosion protection and mitigation, railroad damage and defect assessment, big data for civil engineering application, and emergency evacuation for multi-hazards. She possess two US approved and pending patents, published over 70 high quality peer reviewed publications that include one book chapter, 30 journals, and 40 conference papers, which were cited 360 times with an i10-index of 9. She has more than 10 invited presentations and 20 international and national presentations. Dr. Huang is also an associate editor and editorial board member for five international journals, committee member for five distinguishing professional society such as ASCE Structural Condition Assessment and Rehabilitation of Buildings Committee, ASTM Fiber Optic Practices Committee, and SPIE Sensors and Smart Structures Technologies Committee. She also organizes and modulates four international conferences such as ASME IMECE, IWSHM, SPIE Smart Structures & NDE Conference, and the ASCE Pipelines Conference. She is a grant reviewer for NSF CMMI Program, U.S. DOT PHMSA R&D Program, National Research Foundation (NRF) of Singapore R & D, and Energy Market Authority of Singapore R & D. Dr. Huang is also a frequent peer reviewer for more than 40 international journals and conferences. Dr. Huang won the 2015 NDSU Ozbun Economic Development Award, 2016 NDSU Forward Leap Research Award, 2017 NDSU College of Engineering Researcher of the Year and 2017 NDSU Centennial Award.

Abstract:

Concrete has become more and more popular in road constructions due to the facts that concrete lasts longer and its environmental friendness. The United States has 160,955 miles of roads, including the interstate highway system. Lots of roads within the US are suffering various distress problems. To assess the road conditions and track the traffic, multiple facilities are required simultaneously. For instance, vehicle-based image techniques are available for pavements’ mechanical behavior detection such as cracks, high-speed vehicle-based profilers are used upon request for the road ride quality evaluation, and inductive loops or strain sensors are deployed inside pavements for traffic data collection. Having multiple facilities and systems for the road conditions and traffic information monitoring raises the cost for the assessment and complicates the process. In this presentation, a concept of smart concrete pavement system will be discussed for integrated road condition and traffic monitoring to have the concrete pavement performing multiple functions using in-pavement strain-based sensors, which will phenomenally simplify the road condition and traffic monitoring. This system is expected to simultaneously assess and measure the pavement’s structural health condition, the road’s ride quality, the weighing and classification of vehicles passing with a high speed on the road. Such a superior system requires an innovative sensor system, which has been installed and validated in Minnesota's Cold Weather Road Research Facility (MnROAD) operated by MnDOT. The system was approved to be effective for monitoring the health conditions of the pavements, the traffic counts, ride quality evaluation, and weigh-in-motion measurements, and vehicle identification. The smart concrete pavement system is promising to use the existing concrete pavement system for multiple purposes, which gains a considerable efficiency increase as well as a potential significant cost reduction for intelligent transportation system

Biography:

Moncef is a Professor at Western University, Canada. He previously was Technical Director for Imasco Minerals and BCS. He is recipient of several awards, including the CSCE’s Horst Leipholz Medal, the ICE’s Bill Curtin Medal, the Ontario Premier’s Research Excellence Award and the ACI’s Young Member Award for Professional Achievement. A prolific author with more than 300 publications, he ranked in the world’s most cited civil engineers in the 2016 Shanghai Ranking of World Universities and Academic Subjects. Moncef has been active in several technical committees and professional societies, and a member of the editorial boards of several technical journals. 

Abstract:

Experiences gained, lessons learned, and challenges faced in some landmark concrete construction projects will be discussed. This includes some of the world’s tallest buildings, one of the world’s largest pedestrian bridges, and one of the largest and deepest wastewater pumping stations. The gap between research and development and large-scale concrete construction will be emphasized. Opportunities for implementing breakthroughs and modern advances in materials science in concrete structures will be identified and current research needs will be highlighted

Biography:

Elhem GHORBEL  has completed his PhD at the age of 27 years in materials science and engineering from the National High Engineering School of Mines - Paris. She is Professor at the university of Cergy-Pontoise in the department of Civil Engineering (IUT) since 2003. She has several institutional activities and scientific responsibilities at the national and international levels.

Her research interests cover the mix design, the mechanical and fracture behavior of materials ( self-compacting and resin concretes,composites , polymers), the valorization of inert and industrial wastes in concrete,the repairing of concrete by composites, the durability of heterogeneous materials (aging, Chemical attacks, biodegradationand freezing-thawing resistance), …

She has published more than 50 papers in reputed journals and 100 conference papers. She is editorial board member of Advances in Civil Engineering and Modern Civil and Structural Engineering. She was member of organizing and scientific committees of more than 30 conferences.

Abstract:

The main objective of this investigation is to evaluate the effectiveness of repairing damaged concrete using bioressourced composite by comparison to traditional ones.

To hit this target, the developed approaches are both experimental and analytical.

The first part of this study is dedicated to the characterization of the both resins (determination of the gel point and reticulation duration, glass transition temperature and mechanical behavior), the unidirectional composites used in the repairing process (mechanical characteristics) and the concrete (compressive and damage behaviors).

The second part is devoted to the experimental study of repaired damaged concrete loaded under compressive tests. Three different damage rates are applied on the concrete before the reparation. For damage rates less than 30%, mechanical performances (Compressive resistance, Stiffness and ductility) are completely restored or even enhanced for repaired concretes using UCFREP composites. A comparative effectiveness of repairing with UFFRBP requires applying two layers on composites instead one for UCFRE .

The third part of this work is dedicated to analytical modeling of mechanical behavior of confined concrete with composite under compression in one hand, and the tensile behavior of the composite in other hand.

Using Bioressourced composite for concrete reparation seems to have excellent performances comparable to Carbone one which encourages its application for concrete structures in civil engineering.

Biography:

Gintaris Kaklauskas is Professor of Department of Reinforced Concrete Structures and Geotechnique and Director of Research Institute of Building and Bridge Structures at Vilnius Gediminas Technical University (VGTU). He received his PhD and DrSc (Habil Dr) degrees from VGTU and is a real member of Lithuanian Academy of Sciences. He is the recipient of many awards and recognitions, including ASCE best paper Moisseiff Award 2013, Lithuanian Science Prize 2013 and Marie Curie (Senior Research category) grant. He has been a visiting professor (under Fulbright fellowship) at University of Illinois, Urbana-Champaign. His research interests include service ability analysis and constitutive modeling of concrete structures

Abstract:

The presentation will cover important aspects of the analysis and design of reinforced concrete (RC) structures for serviceability. Main effects having the influence on deformation and crack analysis of RC structures will be discussed. The existing approaches of deformation and crack analysis of RC structures will be briefly reviewed. A new concept of crack analysis of RC members based on compatibility of mean strain and stress transfer approaches will be introduced. The governing parameters of crack spacing are obtained by equating mean strains of the tension reinforcement defined by these approaches. It is assumed that a single RC block of a length of mean crack spacing represents the averaged deformation behavior of the cracked member. Based on the experimental evidence, the reinforcement strain within the block is characterized by a strain profile consisting of straight lines representing zones with different bond characteristics: the debonding, effective and central zones. The sum of the above will result in the crack spacing. To arrive at rational constitutive modeling, the derivation of tension stiffening relationships using the inverse technique will be explained. This is followed by the elimination of shrinkage effect on curvatures and tension stiffening. An account of the accuracy of deformation predictions by various techniques will be given

Biography:

Huanjun Jiang is working as a Professor at Tongji University, China. His research interest includes- RC Structures, Steel-concrete Composite Structures, and Earthquake Resistance of Engineering Structures. He has published many papers in reputed Journals

Abstract:

For reinforced concrete (RC) structures located in seismic zones, reinforcement corrosion over time has adverse effects on their seismic performance. It is necessary to evaluate the effect of reinforcement corrosion on the seismic performance of RC structures. At first, an experiment on corroded RC moment-resisting frames was carried out to investigate the effect of longitudinal reinforcement corrosion on the seismic behavior of RC frames. Six 1/2-scaled frame specimens, including five corroded frames and one frame without corrosion, were tested under quasi-static cyclic loading. The corrosion ratio of longitudinal reinforcement and the axial compression ratio were the main variable parameters. Secondly, Finite element models of corroded RC beams, columns and frames were developed with the aid of the finite element software ABAQUS. Detrimental effects of steel corrosion on the structural performance were considered in the numerical model. The computation simulation results agree well with the test results. Thirdly, by using the calibrated numerical model the deformation limits for all performance levels of corroded RC beams and columns were derived by a large amount of parametric study. Finally, A four-story RC moment-resisting frame was designed according to the current Chinese seismic design code. Based on the deformation limit value corresponding to the individual performance level of RC frame previously derived, the exceeding probability of each performance level of the structure under specific ground motion level was calculated. The seismic fragility curve of each performance level for the structure was developed by the nonlinear least square method. The research results obtained in this study can be utilized for life-cycle oriented seismic performance evaluation of RC structures