PHÂN TÍCH kết cấu LIÊN hợp THÉP bê TÔNG TRONG điều KIỆN CHÁY có xét đến QUÁ TRÌNH TĂNG NHIỆT và GIẢM NHIỆT tom tat tieng anh

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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF CONSTRUCTION HANOI ARCHITECTURAL UNIVERSITY TRUONG QUANG VINH ANALYZE STEEL-CONCRETE COMPOSITE STRUCTURES UNDER FIRE CONDITIONS INCLUDING HEATING AND COOLING PHASE OF THE FIRE PROFESSION: CIVIL AND INDUSTRIAL CONSTRUCTION ENGINEERING Code: 62.58.02.08 SUMMARY OF THE DOCTORAL THESIS Supervisor: Prof.Dr Nguyen Tien Chuong HANOI - 2018 The thesis is completed at: HANOI ARCHITECTURAL UNIVERSITY This thesis can be found at: National library and Hanoi Architectural University INTRODUCTION Context of the research Composite steel-concrete structures are increasingly used in construction works due to good loading capacities Composite structure has one advantage over steel structure is higher fire resistance However, the calculation of the steel-concrete composite structure under fire conditions is very complicated, so there are not many documents mentioned New regulations and standards of Vietnam give experimental method to determine the fire resistance of structures without mentioning structural analysis under fire conditions Most studies on building structures under fire conditions only study the behavior of the structure during the heat-up phase of the fire without considering the decay phase of the fire In fact, many buildings collapsed when the fire was in the cooling phase, so the problem of structural analysis in fire conditions considering the cooling phase is necessary Research purposes Study on the behaviour of steel - concrete composite structures under fire conditions, taking into account the heating phase and also the cooling phase of the fire Studied objects and scope Studied objects: steel-concrete composite elements and structures Scope of the research: behavior of steel-concrete composite structural elements and planar frames, under fire conditions including cooling phase Reasearch methodology The thesis uses theoretical research methodology: (1) Select the concrete material model suitable for both loading and unloading stages of structures under fire conditions (2) Add new material model into computer code SAFIR; (3) Analyze the behaviour of composite steel-concrete structural elements and plane frames, under fire conditions including cooling phase; (4) Study numerically the behavior of structures under fire conditions The contributions of the thesis - Propose thermal and mechanical model of concrete materials for analyzing steel-concrete composite structures under fire conditions, taking into account both heating phase and cooling phase of the fire Select concrete material model which separates transient creep strain and stress-related strain; this model is more accurate in structural analysis with unloading stage of structures under fire conditions Programme concrete model named CONC-ETC, add to structural analysis software SAFIR; - Analyze the behaviour of planar steel-concrete composite frames under fire conditions Do parametric studies on the fire resistance of steel-concrete composite beams and columns; the studies parameters are: load ratio, restrained conditions, heating faces of the elements ; - Develope the idea of using DHP indicator to evaluate structures under fire conditions (DHP is a structural assessment indicator in natural fires with both heating and cooling phase) Write the algorithms for calculating DHP indicator Study the parameters affecting the DHP of steel - concrete columns Find the relation between DHP and some parameters that mainly affect DHP such as load ratio, type of column, material strength, eccentricity of axial load Suggest DelayT indicator to evaluate the potential for structural failure during cooling phase of the fire Study the parameters affecting the DelayT of steel - concrete columns Find the relations between DelayT and main parameters The structure of the thesis Apart from the introduction and conclusion, the dissertation consists of chapters with 22 tables, 114 drawings The dissertation is presented on 146 pages and two appendixes show the programming parts The reference document introduces 125 documents in Vietnamese and English Chapter Overview of analyzing building structures under fire conditions Chapter Methodology and codings for analyzing the behavior of steel-concrete structures under fire conditions Chapter Study on the behaviour of steel-concrete composite frames during the heating phase of the fire Chapter Study on the behaviour of steel-concrete composite frames during the cooling phase of the fire CHAPTER OVERVIEW OF ANALYZING BUILDING STRUCTURES UNDER FIRE CONDITIONS 1.1 Introduction of analyzing structures under fire conditions Figure 1.1 Time - temprature curve 1.2 Evaluating fire development in buildings Each fire usually has three stages of temperature: the start of the fire, the period of heat up, and the period of cooling Most studies only concern the heating stage and consider it the most dangerous stage Calculating the temperature from the source of combustion to the structural surface belongs to the "fire analysis" step not within the scope of this research, and each real fire has a its own time temperature curve For structural analysis, it is common to use the standard fire-curves curve (see Figure 1.2) This curve is called the standard fire ISO 834 The ISO 834 fire is defined according to the following equation: T=345log10 (8t+1)+T0 (1.1) where t is the time (minutes), T0 is the ambient temperature (20°C) and T is the temperature at time t Figure 1.2 Several fire curves according to ISO 834 1.3 Temperature distribution inside the structural members In the steel-concrete composite structure, the heat transfer is calculated by the Fourier equation with the assumption that there is no gap between the steel and concrete This research uses the software SAFIR of the University of Liege-Belgium to calculate the temperature inside the structural members 1.4 Properties of materials at high temperatures 1.4.1 Steel Stress-strain relationship of steel at high temperature: As the temperature rises, the elastic modulus, elastic limit and yield strength of steel are reduced (Figure 1.8) The reduced values are given in Eurocode EN 1992-1-2 1.4.2 Concrete Concrete also reduces the strength as the temperature rises The stress-strain relationship curves of the concrete at different temperatures as shown in Figure 1.13 Similar to steel material, reduced values of strength and modulus of concrete at high temperatures are given in Eurocode EN 1992-1-2 Figure Graphical presentation of the stress-strain relationships of structural steel at elevated temperatures Figure 13 Graphical presentation of the stress-strain relationships of concrete at elevated temperatures 1.5 Over view of researches on buillding structures under fire conditions 1.6 Over view of design standards for buillding structures ensure fire safety 1.7 Introduction to steel - concrete composite structure 1.8 Conclusions of chapter - The mechanical and physical properties of the concrete and steel are variable with high temperatures, so the analysis of building structures under fire conditions needs update the properties of the material at each high temperature point; - In Vietnam, researches on structural behaviour of buildings in fire conditions are very limited; - In the world, there have been many studies on steel-concrete composite structures in fire conditions, but mainly in heating phase of the fire Recently, there have been some published results of experimental researches on steel-concrete composite frames considering the cooling phase but rare publications on numerical simulation results; - Construction codes relating to building structural design for fire safety require to determine the fire resistance of structural components Most codes accept the method for determining the fire resistance is testing or calculating, but very few foreign standards (such as Eurocodes and ASCE standards) have already the instructions to calculate the fire resistance Vietnam has not yet standard for calculating building structures in fire conditions Even the steel-concrete composite structure in fire conditions is not yet mentioned in Vietnam standards; With the above comments, the research concerns the method of simulating steel-concrete composite frame structures under fire conditions considering both heating and cooling phases of the fire Then apply the numerical simulation method to perform calculations, giving the rules of the structural behavior CHAPTER METHODOLOGY AND CODING FOR ANALYZING STEEL-CONCRETE COMPOSITE STRUCTURES UNDER FIRE CONDITIONS 2.1 Numerical method of analyzing steel-concrete composite structures under fire conditions, using SAFIR software To analyze a structure under fire conditions, there are three steps: Step 1: Calculate the development of the temperature from the source of combustion to the surface of the structure; Step 2: Calculate the heat transfer from the structural surface to every point inside the structure (thermal analysis) ; Step 3: Analyze the behavior of the structure under elevated temperature (structural analysis) In the field of construction engineering, this study concerned step and step This section covers the contents of Steps and above, using the SAFIR software SAFIR is a non-linear code developed at the University of Liege to analyze the behaviour of composite structures under normal and fire conditions It is especially devoted to the analysis of structures under elevated temperature conditions, although it can also be used to analyse structures under ambient conditions This software has been verified by comparing the results of the calculation with the results of the experiment or results calculated by other popular software 2.1.1 Thermal analysis Beams and columns are divided into several elements to assume that the temperature is uniform distributed along the axis of each element The beam or column conditions exposed to different fire models are divided into different elements In order to know the temperature on each element, it is necessary to calculate the temperature distribution on the cross section of the element Figure 2.1 shows the cross sectional temperature of the hollow steel column filled with concrete and inner steel profile, showing one-fourth of the cross section due to the symmetry Diamond 2012.a.0 for SAFIR FILE: PROFILE14-R112 NODES: 395 ELEMENTS: 363 NODES PLOT SOLIDS PLOT CONTOU R PLOT TEMPERATURE PLOT Y X Z TIME: 6000 sec 1005.40 895.04 784.68 674.31 563.95 453.59 Figure Temperature in a column section 2.1.2 Structural analysis In structural analysis, the deformation and internal forces of the structure at each fire time shall be calculated corresponding to the temperature in the structure determined in step At each fire time, the mechanical properties of the material at determined temperature are updated The steel-concrete composite frame is simulated by beam elements connected to each other Each element is a bundle of parallel fibers, each fiber can be made of a material 2.2 Stress-strain variation in building structures under fire conditions Using SAFIR code, a number of steel and concrete composite beams and columns were simulated to investigate stress-strain during fire conditions The results show that the structure exists in a variety of stress and temperature situations: increasing stress along with increasing temperature, decreasing stress along with increasing temperature, decreasing stress and decreasing temperature, increasing stress and reduce the temperature The question is whether the material model used in the SAFIR software is suitable to simulate the structure in both heating and cooling phase of the fire Section 2.3 describes stress-strain models of materials under high temperature conditions that have been proposed from other studies and has been selected in this research 2.3 Select material models Mathematical models for steel material have been studied extensively and consensually, but the mathematical models for concrete are divided into two forms, each of which results in significant different results 2.3.2 Concrete model Total strain of concrete (  tot ) at high temperature and under loading includes: (2.4) ε tot =ε th +ε σ +ε tr +ε cr  th : free thermal strain;   : stress-related strain  cr : creep;  tr : transient creep strain  th depends on temperature In this research  th is based on the formula in Eurocodes 11 of the block diagram for the CONC-ETC material (Figure 2.13) The program is written in the Fortran programming language Figure 13 Block diagram of the SAFIR code 12 2.5 Model validation CONC-ETC model has been validated by comparing the results using proposed model (ETC model), results using the current model of Eurocodes (EC2 model) and the experimental results from other researches 2.5.1 Experiment at the University of Technology, Vienna, Austria Figure 14 Comparison of strain results calculated using two models and experimental results Cylindrical concrete samples of 80 mm diameter, 300 mm high, were measured under compressive stress and temperature changing 2.5.2 Experiment at South China University of Technology, China 2.5.3 Experiment at University of Michigan, the USA 2.5.4 Experiment at University of Liege, Belgium The test results were compared with the result calculated by SAFIR code using the concrete model according to Eurocodes (EC2) and the proposed model (ETC) Thereby, the proposed model results in a closer approximation to the test results 2.6 Conclusions of chapter -The variations of stress-strain in steel-concrete composite components under fire conditions are complex Many cases of temperature - stresses - strain change of the structure in the cooling phase of the fire, while most published studies concern only the structural behavior during the heating phase of the fire; -This research has added explicit model of concrete to SAFIR code and named it CONC-ETC; 13 -The proposed model of concrete (CONC-ETC model) has been validated by comparing calculated results ans test results Results using CONC-ETC model is closer to the experimental results compare to results using model in the current Eurocodes CHAPTER STUDY ON THE BEHAVIOUR OF STEELCONCRETE COMPOSITE FRAMES DURING THE HEATING PHASE OF THE FIRE 3.1 Introduction 3.2 The behaviour of composite steel-concrete beams under fire conditions 3.2.1 Influence of the thermal strain Calculating steel beam I 330 supported 100mm thick concrete slab under fire without loading The results show that with beams having restrict axial displacement, thermal deformation causes internal forces in the beam even though there is no load The internal forces in the beam are always changing during the fire and can change into opposite side 3.2.2 Influence of the boundary conditions Modification of the boundary condition of the beam: fix - fix, fixsliding, pin - roller Results calculated by SAFIR software shows that with the beams which can have free thermal displacement, the fire resistance are the same For beams that have restrict axial displacement, the boundary conditions significantly affect the fire resistance 3.2.3 Influence of load ratio The results show that the bigger load factor , the lower fire resistance 3.3 Behaviour of composite steel-concrete columns under fire conditions 3.3.1 Stress - strain in columns without loading under fire The analysis results show that due to the different thermal expansion, the stresses and strains in the columns are complex, which is not follow to the rules of stress-strain distribution at normal temperature 3.3.2 Influence of the way column surfaces exposed to the fire 14 The results show that the thermal strains affect much the behaviour of the column so the way the column faces contact with fire significantly affect the behavior of the column 3.3.3 Influence of load ratio 3.3.4 Influence of column slenderness The results show that the fire resistance of the column decreases markedly when the slenderness increases With different column sections but the same slenderness, the fire resistances of the columns are also significantly different 3.4 Behaviour of steel -concrete composite planar frames under fire conditions The thesis presents the simulation results of the planar frame in Cardington tests (Test No 2) This is one of six prototype experiments on the 8-storey composite frame model at Cardington by the Building Research Establishmen - Britain (BRE) Calculated results are compared with the results of the experiment to verify the model Then, using the proven model, internal forces and deformations in the frame were investigated with different beam stiffness and three different fire positions 3.4.1 Behaviour of beam-column connections This section lists some published studies on the behavior of beamcolumn connections in fire conditions The thesis was based on Gernay T.' s research to analyze the behaviour of planar frames 15 3.4.2 Influence of beam-column connection rigidity The rigid connection model result in significantly smaller displacement than test results For further research, it is necessary to study the behavior of the semi-rigid connections 3.4.3 Influence of the fire location The frame was analyzed with three cases of fire location: fire in whole 4th floor, fire in whole 2nd floor, and fire in the 1st span of the 4th floor (Fig 4.38) The results show that the ultimate temperature in beam at fire is the same in three cases of fire location The changes in bending moments with beam temperature are little different in three cases due to the little differences in Fig 3.48 Frame and location of survey elements rigidities of beam to column connections 3.4.4 Investigating the change of internal forces in the beams and columns during the heating phase of the fire This section presents the results of internal forces change in beam and columns during the heating phase while the load is unchanged The results show that direct fire components have significant changes in internal force and deformation during fire, the further away components from the fire, the less influence In the columns there is a large change of moment due to the thermal expansion of the beam connects to the head of the column The axial force in the column also changes during fire but not significantly In beams, it appears great compression force due to thermal expansion Thus, it is 16 unreasonable to take the internal forces unchanged during the fire process 3.5 Conclusions of chapter - Structures in fire conditions behave very complicated by thermal deformation, which contributes significantly to the general structural deformation; - The fire resistance of the structure depends on the load ratio When the load is increased, the fire resistance is markedly reduced; - In beams with the same load ratio, their fire resistance are influenced by the boundary conditions; - When the structure is subjected to fire, the internal forces of the components exposed to fire increases significantly compared to internal forces at normal temperature It is unreasonable to take the internal force unchanged during the fire; - The internal force in the planar frames during fire is significantly influenced by temperature and boundary conditions At high temperature, the beam column connections changes the rigidity, so it needs further research on the behavior of beam-column connections to clarify the behavior of the frame CHAPTER STUDY ON THE BEHAVIOUR OF STEELCONCRETE COMPOSITE FRAMES DURING THE COOLING PHASE OF THE FIRE 4.1 Behaviour of steel -concrete composite planar frames under cooling phase of the fire In the last few years, the behavior of the structure at the cooling phase of the fire and after fire stage is of concern Calculated results show that the internal forces in structures at the cooling stage of the fire can be greater than the internal forces at the end of the heating period Thus, it is possible that the structure has not failed during the heating phase but fail during the cooling phase In addition to the ability to increase internal force in the structure during the cooling phase, the structure can further reduce the bearing capacity when the outside temperature has decreased 17 Figure 4.3 Time-temperature curves used in analyzing the frame 4.2 The concept of Duration of the Heating Phase (DHP) Indicator The term 'duration of the heating phase' is described by Gernay T and Franssen J.M in 2015 By definition, the DHP represents the minimum exposure time to standard ISO fire (followed by cooling phase in accordance with the Eurocode parametric fire model) that will eventually result in the failure of the structural component The load capacity of the structure decreases as the temperature rises The red line in Figure 4.7 shows the load bearing capacity of a column as the temperature increases with the standard fire The green line shows the load bearing capacity of the column as the temperature rises for a period of 30 minutes and then decreases The blue line shows the load bearing capacity of the column as the temperature rises for a period of 59 minutes and then decreases 18 Figure 4.7 Relationship between load capacity of the column and time of fire Assume the column is subjected to a design load of 60% of its ultimate load at room temperature If the temperature rises as the standard fire, then after 93 minutes the load capacity of the column reduced to 60% compared to the original Therefore, the fire resistance of the column R = 93 minutes If the temperature increases in only 30 minutes then decreases, the load capacity of the column decreases but is larger than the design load so the column is not damaged Similarly, calculations with natural fires having heating time of 30 minutes, 40 minutes , the load capacity of the column is still greater than the design load (60% of its ultimate load at room temperature )so the columns does not fail Continue increasing the time of the heating phase to 59 minutes, the column fails at 113th minute of the fire, while the column is in the cooling phase The minimum value of the heating time that still causes structural failure in the cooling stage is 59 minutes We said DHP = 59 minutes The thesis proposed the calculation of DHP for the steel-concrete composite column and using the SAFIR software to examine 19 parameters affecting the DHP of the steel-concrete composite column 4.4 Develop a algorithm for calculating DHP of steel-concrete composite columns 4.4.2 The AutoIT application for programming automatically calculation of DHP Input Structural Member Geometric and Mechanical Properties Input Applied Load Calculate R (Call SAFIR program) 1200 initialization i = 0, Heat t i= R read t_step Heat T i=i+1 Heat T Heat T 360 i-1 i i (Using Parametric Eucorode Model) Thermal Analysis (Call SAFIR program) (for the whole fire duration) Structural Analysis (Call SAFIR program) (for the whole fire duration) Yes Failure ? No DHP = Heat t i-1 Figure 4.11 Block diagram of the program automatically calculates DHP 20 4.5 Parametric studies on DHP of steel-concrete composite columns Seventeen cross-sections have been studied This part shows six typical cross-sections (Error! Reference source not found 4.12) The other cross-sections are similar to the cross-section types of the profiles in Error! Reference source not found but different dimensions and different steel profiles The steel profiles are accordant with European standards R, DHP and Tfail (the time of failure) Tare calculated for columns with various load ratio, column length, concrete grade, the eccentricity of load and fire curve Tfail is the duration (in minute) from the beginning of the fire to the moment structures fail a) Profile b) Profile c) Profile d) Profile 14 C 219.1 x HEB 120 S 200 x HEB 120 S 300 x 6.3 HEB 220 S 350 x HEB 260 e) Profile 13 f) Profile 15 C 406.4 x C 273x12 C 355.5 x C 273x12 Figure 4.12 Cross-sections of studied columns 4.5.1 Influence of load ratio Columns are calculated with load ratios of 0.3 to 0.6 The results show that the load ratio significantly influences R, DHP and Tfail The larger the load ratio, the smaller R and DHP 4.5.2 Influence of outer steel tube's strength Maintain the load, change the outer steel tube's strength ( f y ) see R and DHP not change much R and DHP were not significantly when f y increase It can be explained that the temperature of the outer steel tube increases very rapidly, so the outer steel tube does not contribute significantly to the load-bearing capacity of the columns 4.5.3 Influence of inner steel profile's strength Columns are calculated with the values of inner steel strength of 235, 275, 355, 420 and 460 MPa DHP does not change noticeably with inner steel strength 21 4.5.4 Influence of concrete strength Columns are calculated with the values of concrete strength of 20,30,40,50 and 60 MPa DHP does not change noticeably with concrete strength 4.5.5 Influence of eccentricity of load The column is calculated with eccentricity of load from 0.125b to 1.5b (b is the sectional dimension) Keep load ratio unchanged, R and DHP not change significantly with eccentricity of load In simplified method, DHP of columns under eccentric compression can be taken as DHP of columns under concentrate load, in the safe side 4.5.6 Influence of slenderness of column Columns are calculated with column height between 2m and 7m The results showed that DHP significantly affected by the slenderness of column 4.5.7 Notion of delay failure time (DelayT) Delayed failure time (DelayT) is the duration (in minute) from the end of heating phase to the moment structures fail: DelayT = Tfail - HeatT 4.6 Parametric studies on DelayT of steel-concrete composite columns 4.6.1 Influence of heating time HeatT Table 4.7 Results of columns profile 14 Tfail and DelayT are calculated with different fire curves (different HeatT) With results of parametric studies of various columns and value of heating phase, it is recognized that DelayT trends to be greater with small HeatT 22 4.6.2 Influence of load ratio Columns are calculated with load ratios of 0.3 to 0.6 The results show that the load ratio significantly affects Tfail and DelayT In most cases, Tfail and DelayT decrease as the load ratio increases 4.6.3 Influence of concrete strength The results show that the strength of concrete does not significantly affect the R, HeatT and Tfail results if the value of the load ratio is maintained 4.6.4 The greatest value of DelayT in studied columns The value of DelayT is important with fire fighters who need to know to keep off the failure of the buildings Therefore, one objective of this study is to know how great the value of DelayT could be for studied structural elements With results of parametric studies of various structural elements, it is recognized that DelayT trends to be greater with high fire resistance and small HeatT Therefore, steel-concrete composite columns are calculated to find the great value of DelayT Column profile 17 has DelayT can be up to 252 minutes 4.7 Conclusion of chapter - Structural collapse of the buildings during the cooling phase of the fire is possible These result from different mechanisms such as the effects of thermal inertia or the additional loss of mechanical properties during cooling phase The delay failure of the structure in the fire should be further researched, contributing to the safety of fire fighting and rescue work - The design standards concern only R without mentioning DHP A structure has been designed to ensure that it meets the requirement of fire resistance (R) is not guaranteed not fail in the cooling phase of the fire So if the R indicator is specified in the design standard to ensure that the structure does not fail during the heat-up period to cover the rescue time, the DHP indicator should be specified to ensure the structure does not fail during the cooling of the fire; - Parametric studies on DHP show that: + Load ratio and column slenderness mainly affect DHP; 23 + Strength of materials and eccentricity of load does not affect significantly DHP In simplified method, DHP of columns under eccentric compression can be taken as DHP of columns under concentrate load; - In designing building structures for fire safety, it needs concern "Delay failure time" (DelayT) also The value of DelayT is important to the safety of fire fighting and rescue work; - Parametric studies on DHP show that: + Duration of heating time an load ratio significantly affect DelayT; + Strength of concrete and eccentricity of loading does not significantly affect DelayT if the value of the load ratio is maintained; + In studied columns, DelayT can raise up to 250 minutes This means that the building could collapse after 250 minutes since the temperature of the fire is controlled down CONCLUSION From the research results, in comparison with the research objectives, the thesis draws the following major conclusions: - The CONC-ETC concrete model, which separates transient creep strain and stress-related strain, is more accurate in analyzing structures in both the loading and unloading stages under fire conditions The research has added CONC-ETC model to SAFIR sofware; - Numerical analyzing the behaviour of planar steel-concrete composite frames under fire conditions show that: thermal deformation significantlty affect the behaviour of structures under fire conditions, thermal deformation contributes significantly to the general structural deformation; boundary conditions and load ratio affect significantly the structural behaviour; - Structural collapse of the buildings during the cooling phase of the fire is possible These result from different mechanisms such as the effects of thermal inertia or the additional loss of mechanical properties during cooling phase Parametric studies on DHP (minimum heating time of a fire that will result in the failure of the structural component in the cooling phase of the fire) show that: load 24 ratio and column slenderness mainly affect DHP; strength of materials and eccentricity of load does not affect significantly DHP; - In designing building structures for fire safety, it needs concern DelayT (the duration from the end of heating phase to the moment structures fail) also The value of DelayT is important to the safety of fire fighting and rescue work Parametric studies on DHP show that: Duration of heating time an load ratio significantly affect DelayT, Strength of concrete and eccentricity of loading does not significantly affect DelayT if the value of the load ratio is maintained; In studied columns DelayT can raise up to 250 minutes It means that the building could collapse after 250 minutes since the temperature of the fire is controlled down Prospectives - Extend the scope of the study: behaviour beam-columns conections, spacial structures ; - Continue doing parametric studies on DHP and DelayT indicators Propose practical method to calculate DHP and DelayT; - Study the behaviour of steel-concrete composite structures after fire (when the temperature has been down to 200C) LIST OF WORKS RELATED TO THE THESIS HAS BEEN PUBLISHED Chu Thi Binh, Truong Quang Vinh (2013), Caculation of fire resistance of reinfored concrete strutures Proceeding of Conference IBST, pp 93 -102 (in Vietnames) Chu Thi Binh, Truong Quang Vinh, Nguyen Tien Chuong (2014), Influence of boundary conditions on the behaviour of concrete beams in fire, Proceeding of Conference, Thuy Loi University, pp 133 -135 (in Vietnames) Truong Quang Vinh, Chu Thi Binh (2015), Behaviour of steelconcrete composite frames under fire conditions Nghiên cứu ứng xử khung liên hợp thép - tông điều kiện cháy, Proceeding of the National Conference Solid Mechanic 12nd, pp 1653 - 1660, Volumn (in Vietnames) Truong Quang Vinh, Nguyen Tien Chuong, Chu Thi Binh (2017), Failure of Steel-concrete composite coulmns during the Cooling Phase of a Fire, Journal of Construction, No 8, pp 64-69 (in Vietnames) Chu T.B., Truong Q.V (2018) Numerical Studies of Composite Steel-Concrete Columns Under Fire Conditions Including Cooling Phase In: Tran-Nguyen HH., Wong H., Ragueneau F., Ha-Minh C (eds) Proceedings of the 4th Congrès International de Géotechnique - Ouvrages -Structures CIGOS 2017 Lecture Notes in Civil Engineering, vol Springer, Singapore Truong Q.V., Pham T.H., Chu T.B (2018) Failure of Building Structural Members During the Cooling Phase of a Fire In: Nguyen-Xuan H., Phung-Van P., Rabczuk T (eds) Proceedings of the International Conference on Advances in Computational Mechanics 2017 ACOME 2017 Lecture Notes in Mechanical Engineering Springer, Singapore ... of steelconcrete composite frames under fire conditions Nghiên cứu ứng xử khung liên hợp thép - bê tông điều kiện cháy, Proceeding of the National Conference Solid Mechanic 12nd, pp 1653 - 1660,... Eurocode EN 1992-1-2 5 Figure Graphical presentation of the stress-strain relationships of structural steel at elevated temperatures Figure 13 Graphical presentation of the stress-strain relationships... the thesis Apart from the introduction and conclusion, the dissertation consists of chapters with 22 tables, 114 drawings The dissertation is presented on 146 pages and two appendixes show the programming
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