AEM SIMULATION OF SEISMIC RETROFITTING METHODS OF UNREINFORCED MASONRY RAILWAY STRUCTURES రಕͶ͕͜Ζໃ۔ૌߑଆଳਔึک๏๑ Ͷͯ͏ͱ $(0 ͶΓΖ਼εϝϣϪʖεϥϱ by PHAN Thanh Ngoc Student ID number: 17RB903 A Dissertation submitted to Yokohama National University In partial fulfillment of the requirements for the degree of Master of Engineering Supervisor Professor Akira HOSODA Graduate school of Urban Innovation Yokohama National University Yokohama, Japan January 2019 ACKNOWLEDGEMENT The author would like to express his great appreciation to his research supervisor, Prof Dr Akira Hosoda for his patient guidance, invaluable suggestions, enthusiastic encouragement and useful critiques at every stage of this research work The author is equally grateful to Prof Dr Hamed Mohamed Mahmoud Salem, Structural Engineering Department, Cairo University, Egypt for his consistent guidance and supports the author in doing numerical analysis using Extreme Loading for Structures which follows Applied Element Method The author’s grateful thanks are also extended to Mss Sakiko Takahashi, Assistant Manager, Structural Engineering Center, East Japan railway company for her kind help in doing data analysis of experimental results The author extends his thanks to project 599 of Vietnam International Education Development of the Ministry of Education and Training of Vietnam which gave a good scholarship for supporting his study Finally, the author wishes to thank his parent and older brother for their encouragement and support throughout his study i|Page ABSTRACT AEM SIMULATION OF SEISMIC RETROFITTING METHODS OF UNREINFORCED MASONRY RAILWAY STRUCTURES రಕͶ͕͜Ζໃ۔ૌߑଆଳਔึک๏๑Ͷͯ͏ͱ $(0 Ͷ ΓΖ਼εϝϣϪʖεϥϱ According to previous surveys on railway structures in the metropolitan area of Japan, it has been reported that there are some old unreinforced masonry structures made of bricks or stones or plain concrete while are in service In order to enhance the performance of unreinforced masonry piers in very limited spaces under severe seismic actions, many kinds of strengthening techniques have been planned by JR EAST company in Japan such as vertical-prestressed steel, grid-steel plate and Concrete Filled Tubes (CFT) methods The basic concept of the methods is to prevent the large horizontal sliding and residual displacement at the mortar joints between bricklayers which may cause catastrophic failure of structures or difficulty of early resuming railway service after the earthquake In this study, an attempt is made to apply the Applied Element Method (AEM) which is highly developed for simulating the experimental results in the case of Grid-steel plate retrofitting method Two separated low strength concrete column was retrofitted by gird-steel plate method A Polyvinyl Chloride (PVC) sheet was inserted between the joint of two column blocks to expect the reduction of the sliding friction when horizontal displacement was applied to the specimen The Grid-steel plates were arranged on the two side surfaces of the column and joined with the penetrating reinforced bars The investigated cases include the alteration of the dimensions, the thickness and the arrangements of the steel plates in the vertical direction to assess the sensitivity of the related influencing factors on the performance of the testing specimens The grid-steel plate retrofitting method showed good contribution to mitigate the sliding behavior of the retrofitted column at the joint and caused rocking behavior at the base The numerical monotonic and cyclic analysis results showed that the crack occurrences, crack propagation, load-displacement relation and failure pattern of the experimental specimens are quite comparable and highly validated In addition, some possible techniques for the next stage of the research is also demonstrated ii | P a g e CONTENTS ACKNOWLEDGEMENT i ABSTRACT ii TABLES v FIGURES vi CHAPTER INTRODUCTION 1.1 Background 1.2 Objectives and scope 1.3 Brief outline of the study 1.3 Methodology and verification process in the study 1.4 Justification of the research 1.5 Organization of the Thesis CHAPTER LITERATURE REVIEW 2.1 Previous studies on the seismic failure mode of unreinforced masonry railway structures 2.2 Previous studies on seismic retrofitting methods of unreinforced masonry railway structures 2.3 Previous studies on seismic retrofitting methods of unreinforced stone masonry bridge piers 2.4 Numerical simulation of masonry 2.5 Conclusion CHAPTER 10 CONCEPT OF THE RETROFITTING METHOD 10 3.1 Working condition of the existing unreinforced masonry railway bridges 10 3.2 Basic concept of the retrofitting methods 10 3.3 Main seismic retrofitting methods 11 3.3.1 The Grid-steel plate retrofitting method 11 3.3.2 The Vertical-prestressed steel retrofitting method 12 CHAPTER 13 AEM SIMULATION AND METHOD OF VERIFICATION 13 4.1 Applied Element Method (AEM) 13 4.2 AEM and FEM in comparison 13 4.3 Software used for the Analysis following AEM 14 4.4 AEM material models in the study 14 4.4.1 Concrete model 14 4.4.2 Reinforcing bars model 15 4.4.3 Bearing material model 16 4.4.4 Elastic material model 16 4.5 Justification of using AEM as a numerical analysis method for the research 17 4.6 Basic assumptions in AEM simulation 18 CHAPTER 19 AEM ANALYSIS OF GRID-STEEL PLATE RETROFITTING METHOD FOR MASONRY PIERS OF RAILWAY BRIDGES 19 5.1 Experimental program 19 5.1.1 General 19 iii | P a g e 5.1.2 Specimen’s details 19 5.1.3 Materials 22 5.1.4 Testing procedures 22 5.1.5 Testing results 23 5.2 Verification of AEM simulation Case 26 5.2.1 Interface material between concrete blocks and PVC sheet 28 5.2.2 Interface material between concrete columns and steel plates 29 5.2.3 Verification of simulation 29 5.3 Verification of AEM simulation Case 30 5.3.1 Interface material between concrete blocks and PVC sheet 32 5.3.2 Verification of simulation 33 5.4 Verification of AEM simulation Case 33 5.4.1 Interface material between concrete blocks and PVC sheet 35 5.4.2 Verification of simulation 35 5.5 Conclusions and future study 36 5.5.1 Conclusions 36 5.5.2 Future study 36 CHAPTER 37 AEM ANALYSIS OF VERTICAL-PRESTRESSED STEEL RETROFITTING METHOD 37 6.1 Experimental program 37 6.1.1 General 37 6.1.2 Specimen details 37 6.1.3 Materials 39 6.1.4 Testing procedures 39 6.1.5 Testing results 40 6.2 Verification of AEM simulation Case 46 6.2.1 Material properties used in AEM models 46 6.2.2 The use of square section instead of round section when simulating a steel bar 48 6.2.3 Modeling prestressed steel bars in AEM model 49 6.2.4 Monotonic analysis 51 5.5 Conclusions and future study 52 5.5.1 Conclusions 52 5.5.2 Future study 52 CHAPTER 53 CONCLUSIONS 53 7.1 General 53 7.2 Conclusions and recommendations regarding Grid-steel plate retrofitting method 53 7.2 Conclusions and recommendations regarding verification model of AEM simulation using in the research 53 7.4 Future works 54 iv | P a g e TABLES Table Details of steel plates, steel anchors, sheath tubes and steel bars 20 Table Details of columns and PVC sheet 20 Table Characteristics of concrete 22 Table Characteristics of steel 22 Table 5 Material properties of concrete and steel in ELS models 27 Table Properties of bearing material in ELS models .27 Table Properties of interface material in ELS models .27 Table Properties of elastic material in ELS models 27 Table Interface material assignment 28 Table 10 Material properties of concrete and steel in ELS models 31 Table 11 Properties of bearing material in ELS models .31 Table 12 Properties of interface material in ELS models 31 Table 13 Properties of elastic material in ELS models 31 Table 14 Interface material assignment 32 Table 15 Material properties of concrete and steel in ELS models 34 Table 16 Properties of bearing material in ELS models .34 Table 17 Properties of interface material in ELS models 34 Table 18 Properties of elastic material in ELS models 34 Table 19 Interface material assignment 35 Table Prestressed force used in the test …………………………………………………….38 Table Characteristics of concrete 39 Table Characteristics of steel 39 Table Material properties of concrete and steel in ELS models 47 Table Properties of interface material in ELS models .47 Table 6 Properties of elastic material in ELS models 47 Table Interface material assignment 48 v|Page FIGURES Fig.1 Unreinforced masonry railway bridges in Kantou area Fig.1 Damage of Unreinforced masonry railway structures under earthquakes Fig.1 Brief outline of the study Fig.1 Verification process of AEM simulation Fig.2 The Great Kantou Earthquake’s damage to Minatogawa bridge…………………………………………………………… ………………………………5 Fig.2 Loading test on brick masonry wall Fig.2 The degree of seismic resistance Fig.2 4Partial steel plate retrofitting method Fig.2 5Horizontal loading test Fig.2 6Typical Elevation Views of Rest Piers with Proposed Mini-piles as Strengthening Reinforcement Fig.2 State of stresses in a masonry prism subjected to vertical compression .9 Fig.3 Rocking behavior after retrofitting………………………………………………………10 Fig.3 The use of brackets to prevent falling and overturning .11 Fig.3 The grid-steel plate retrofitting method 11 Fig.3 The Vertical-prestressed retrofitting method 12 Fig.4 Connectivity matrix spring ………………………………………………………………13 Fig.4 Analysis domain of AEM compared to FEM 14 Fig.4 Partial element connectivity 14 Fig.4 Concrete material model 15 Fig.4 Reinforcing bars model .16 Fig.4 Bearing material model .16 Fig.4 Elastic material model .17 Fig.4 8-node hexahedron elements .17 Fig.5 The three reinforced concrete specimens ………………………………………………20 Fig.5 The main components of the specimen .21 Fig.5 Construction joint between lower block and footing 21 Fig.5 Spongy pads were inserted to prevent local failure 21 Fig.5 Compressive strength test and splitting test 22 Fig.5 Experimental results Case 23 Fig.5 Diagonal cracks in Case 24 Fig.5 Experimental results Case 25 Fig.5 Experimental results Case 26 Fig.5 10 The interface material in model case 29 Fig.5 11 The elastic interface model .29 Fig.5 12 Monotonic analysis Fig.5 13 Cyclic analysis 30 Fig.5 14 Cracks and failure patterns 30 Fig.5 15 The interface material in model Case 32 Fig.5 16Monotonic analysis Fig.5 17 Cyclic analysis 33 Fig.5 18 Cracks and failure patterns 33 Fig.5 19 Monotonic analysis Fig.5 20 Cyclic analysis 35 Fig.5 21 The crack patterns 36 Fig.6 The main components of the specimen……………………………………….……… 37 Fig.6 Experimental results Case 42 Fig.6 Experimental results Case 44 vi | P a g e Fig.6 Experimental results Case 46 Fig.6 Summation of experimental results 46 Fig.6 Components in ELS model .48 Fig.6 The corresponding square section of steel bar in AEM model 49 Fig.6 Spring controller setting in ELS 49 Fig.6 10 Internal force in the PC steel bar .50 Fig.6 11 Construct scenario option in ELS 50 Fig.6 12 Loading scenario in ELS 51 Fig.6 13 Applying prestressed force using construct scenario in ELS 51 Fig.6 14 Monotonic analysis of Case 52 Fig.6 15 Failure mode of the ELS model Case 52 vii | P a g e ... RETROFITTING METHOD 10 3.1 Working condition of the existing unreinforced masonry railway bridges 10 3.2 Basic concept of the retrofitting methods 10 3.3 Main seismic retrofitting... this study, an attempt is made to apply the Applied Element Method (AEM) which is highly developed for simulating the experimental results in the case of Grid-steel plate retrofitting method Two... of the testing specimens The grid-steel plate retrofitting method showed good contribution to mitigate the sliding behavior of the retrofitted column at the joint and caused rocking behavior