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MINISTRY OF EDUCATION AND TRAINING UNIVERSITY OF TRANSPORT AND COMMUNICATIONS NGUYEN DAC DUC INVESTIGATION THE SHEAR AND TORSION RESISTANCE OF JOINT IN SEGMENTAL BOX GIRDER BRIDGES TECHNICAL DOCTORAL THESIS HANOI 2020 INTRODUCTION Necessity of the title Along with the development of science and technology, the transport engineering industry is constantly growing in the scale, design techniques and construction technology The studies not only suggest structural solutions over larger spans to meet the increasing requirements of navigation clearance as well as overcoming the obstacles with large apertures such as strait, valley Modern construction technologies are also focused on in order to improve the construction conditions, speed up the efficiency of investment capital The first concepts of prefabricated pre-assembled concrete compost elements began to take shape in the early 30s of last century The person who laid the foundation is Eugene Freyssinet, until 1946 did the design and construction of the world's first assembled bridge - Luzancy bridge over the Marne River This is the world's first pre-stressed reinforced concrete arch bridge in which the beam segments are assembled on a temporary scaffolding column and use concrete mortar material as joint filler in the joints Not long after that, therre arre five more arched bridges made of reinforced concrete with a span of 74m span across the Marne River From these initial pilot projects, the countries around the world have continued to build many types of large-scale pre-assembled prestressed concrete bridges with increasingly modern and effective technology solutions in the technical, artistic and economic aspects However, with the type of bridge structure assembled and segmented, the existence of joints will make the bearing mechanism in general and the shear and torsion resistance mechanism in particular different, therefore, in 1959 Franz [3 ] studied on the model of flat, serrated cementitious joints without reinforcement, followed by the studies of Jones in 1959 [3], Buyukozturk, Bakhoum, Beattie in 1990 [25] with dry joints and flat epoxy adhesive and has a non-reinforced anti-cut lock In our country, the assembly technology has been researched by the Transport Industry since mid-2000, focusing on middle span from 40-60m, cross-sections are usually T-sections, box-sections These works have been constructed, although there are many shortcomings, but basically meet the exploitation requirements In recent years, a number of large projects require the fast construction progress such as the Ben Thanh - Suoi Tien Metro Line project in Ho Chi Minh City [7] The project has a length of 19.7km, including 2.6km underground and 17.1km overhead with a 14.5km viaduct section, of which 12km is constructed by the segmented assembly technology, U-shaped girder cross section, joints using anti-shear keys combined with epoxy glue Tan Vu - Lach Huyen project, Hai Phong city [6], the starting point of project Km0 (Tan Vu intersection) intersects Hanoi - Hai Phong expressway in Hai An district, Hai Phong city; The ending point Km15 + 629.94 (Lach Huyen port port) located in Cat Hai district - Hai Phong city, the project has a total length of 15.63 km, bridge length is 4433.7m Cross section of 01 stranded reinforced concrete box girder f’c = 50Mpa 3.2m high, 16m wide) The bridge consists of units, constructed according to Span By Span assembly technology (SBS), the bridge is on a straight line, the joint uses anti-shear key combined with epoxy glue In the process of exploiting, the joint will be the point where adverse working conditions appear when the joint is subjected to shear, torsion The content of the title focuses on the resistance to shear and torsion at the joint to propose the solutions that contribute to more control and completion of design, construction and prediction of the possibility of damage at the joint when affected by the exploitation load Object of research Research the bridge span structure construction according to segmented assembly technology, contact the design and construction works in a number of practical projects that have been and are prepared to deploy in the world and in Vietnam Scope of the research Study the shear resistance, evaluate the influence of torsion on the shear resistance of the joint under the eccentric load Research Methodology The experimental method combined with numerical simulation Conduct the collection and research of domestic and foreign documents Analyze, synthesize and evaluate the researched contents for shear key, experimentally determine shear resistance, analyze simulation and verify experiments Simulation to evaluate the effect of torsion on the shear resistance of the joint Scientific and practical significance of the title The research results aim to indicate the influencing factors as well as determine the shear resistance of the shear key, evaluate the influence of torsion through simulating the number of structures subjected to eccentric loads It is the basis for the design, verification, evaluation and maintenance management units to assess the load capacity as well as the form of shear key failure when subjected to extreme forces Layout of the thesis Introduction Chapter Overview of research issues Chapter Analysis and evaluation of resistance of joint with shear key in a segmented bridge Chapter Experimental research and numerical simulation analysis for evaluation of shear resistance Chapter Effects of torsion on the shear resistance of the joint Conclusion and recommendation CHAPTER 1: OVERVIEW OF RESEARCH ISSUES 1.1 Overview of segmented box girder bridge technology Segmented girder bridge construction technology - Assembly technology on fixed scaffolding system - Progressive Placement Method - Symmetrical balance assembly technology by mobile suspension - Balanced cantilever technology - Complete Span By Span assembly technology (SBS) Fabrication technology of segmented girder node - Long-line casting technique - Short-line casting technique for each segment Application of segmented assembly technology in bridge construction in the world and in Vietnam The bridge-span structures using segmented assembly technology began to be used in the early 1950s for small span bridges In some developed countries, in the 1990s and early 2000s, big firms such as: NS (Norway), Structuras (Australia), RoeRo (Germany), Freyssinet (France), VSL (Switzerland), has deployed the large bridges using the segmented assembly technology In Vietnam, in the early 1980s, moderately-sized pre-stressed concrete box girder segments with a length of 3.5m were applied for the first time in bridges: Fence, Niem and An Duong (Hai Phong), these bridges were designed and built mainly in the form of a T-frame with a main span of 63m in shape In 2003, we successfully built the Kien Bridge across the Cam River in Hai Phong, this was a cable-stayed bridge using a box-shaped cross section, followed by the Tan Vu - Lach Huyen project and Ben Thanh - Suoi Tien Metro 1.2 Joint used in segmented bridge According to AASHTO's classification, the types of joints are classified into types: - Type A: wet joint (using filling material between two segments to create a joint, the material can be concrete, mortar, epoxy adhesive) - Type B: not use material between two segments; According to the type of jointing material, the thickness of the joint can also be divided into the types of joints used in steel structures into six categories as follows: - Type 1: Joints made of concrete placed in place, with waiting reinforcement, 20-60 cm thick - Type 2: joints made of fine-grained concrete, 7-12 cm thick - Type 3: Joints made of cement mortar, - cm thick - Type 4: Joints made of epoxy adhesive, thickness
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