Comparison of Ultimate Capacities of RC Chimney Sections under Wind Loading

Diffusion of gaseous and particulate pollutants from tall stacks has formed an important element in the control of air pollution since the industrial revolution began. These tall reinforced concrete chimneys are considered to be cantilever columns subjected to axial load resulted from the self-weight of the shell, linings and other accessories and bending moments which are resulted from the lateral loads like wind forces and earthquake forces. The recently published IS: 4998 – 2015 adopted a limit state design concept which requires well defined stress-strain relationship for concrete and steel. It has been seen that there are many disparities lies between the stress-strain relationships of constituent materials adopted by IS: 4998 – 2015 and other design standards. This paper discusses various methods pertaining to the estimation of the ultimate strength of thin-walled hollow circular sections of reinforced concrete chimneys, subjected to wind loading. A comparative study of various methods based on the prevalent codes reveals considerable disparity in the predicted ultimate strength values. These differences have been critically analyzed and results are discussed in this paper in terms of ultimate strength along with the contribution of concrete and steel, ultimate curvature and depth of neutral axis. For the comparison of above-mentioned parameters, design recommendations of IS 4998 – 2015, CICIND 2011, ACI 307 – 08 are used. HIGHLIGHTS The recently published IS: 4998 – 2015 adopted a limit state design concept which requires well defined stress-strain relationship for concrete and steel which differs in terms of strain and stress limits when compared with other well established RC chimney design codes Various methods pertaining to the estimation of the ultimate strength of thin-walled hollow circular sections of reinforced concrete chimneys, subjected to wind loading are discussed using a comparative study with different parameters of RC chimney For the comparison of above-mentioned parameters, design recommendations of IS 4998 – 2015, CICIND 2011, ACI 307 – 08 are used Stress-strain relationship of concrete and steel also discussed with the bases of the same is also discussed in detail for each of the above codes GRAPHICAL ABSTRACT

Load & Resistance Factors Calibration for Front Covered Caisson Breakwater

Calibration of load-resistance factors for the limit state design of front covered caisson breakwaters were presented. Reliability analysis of the breakwaters which are constructed in Korean coast was conducted. Then, partial safety factors and load-resistance factors were sequentially calculated according to target reliability index. Load resistance factors were optimized to give one set of factor for limit state design of breakwater. The breakwaters were redesigned by using the optimal load resistance factor and verified whether reliability indices larger than the target value. Finally, load-resistance factors were compared with foreign country’s code for verification.

THE HISTORY OF THE LIMIT STATE DESIGN METHOD

This paper analyzes the 70-year history of development of the limit state design method (LSDM) focusing on the fundamentals of the design codes based on this method and considers proposals for improving the LSDM and its justification. It was also noted that the reaction of the system in any of its fixed states is not always sufficient to assess the reliability of the system, and therefore it is necessary to analyze the rate of loss of resistance of load-bearing structures. However, probabilistic considerations were not enough due to the lack of reliable statistical data in the area of extreme sections of the distribution curves and a number of other circumstances (features of control procedures, different behavior of the material in the structure and in the samples, etc.). This paper analyzes some fundamental issues that should be solved when developing the method for the nonlinear analysis.

A Structural Analysis Of A Factory Hall With A Two-Story Office Building As A Precast And Prestressed Concrete Construction

The objective of this thesis is to develop a precast and prestressed concrete design for a factory hall, which was initially planned as a steel structure. Furthermore, a structural analysis is conducted on several chosen structural elements according to the European Standards and the German Annexes respectively. The analysis is done both by manual calculation and software calculation for comparison and includes the ultimate limit state design, the serviceability limit state design and the design for the state of transportation and assembly of the precast members. Lastly, to illustrate the results of the analysis, an overview drawing with the new concrete design as well as formwork and reinforcement drawings for each of the analyzed structural members are developed.

A Structural Analysis Of A Factory Hall With A Two-Story Office Building As A Precast And Prestressed Concrete Construction

The objective of this thesis is to develop a precast and prestressed concrete design for a factory hall, which was initially planned as a steel structure. Furthermore, a structural analysis is conducted on several chosen structural elements according to the European Standards and the German Annexes respectively. The analysis is done both by manual calculation and software calculation for comparison and includes the ultimate limit state design, the serviceability limit state design and the design for the state of transportation and assembly of the precast members. Lastly, to illustrate the results of the analysis, an overview drawing with the new concrete design as well as formwork and reinforcement drawings for each of the analyzed structural members are developed.