Seismic design of liquid-containing concrete structures

The seismic design of structures is a requirement for any places [sic] where earthquake [sic] occurs, and the design is based upon the codes that vary according to the jurisdictions in which the code was developed for. This study introduces and assesses the document ACI 350.3-06 which was developed by the ACI Committee to guide the design of liquid containing structures, and compares to other codes such as ACI 350.3-01 and NZS 3106 of New Zealand Standard. The importance of liquid containing structures cannot be stressed further, as it is apparent in nuclear applications. The failure of tanks could be due to many reasons: 1) Shell buckling, caused by axial compression due to overall bending. 2) Roof damage as a result of sloshing of the upper portion of the containing liquid due to insufficient provision of freeboard. 3) Failure of inlets and outlets due to their inability to accommodate the deformations of the flexible tank. 4) Differential settlement or failure of supporting soil. The pressures resulted from earthquake [sic] can cause catastrophic disaster, and they [sic] are the impulsive and convective mode which exerts pressures on the walls of the tank. The hydrodynamic model used to estimate these pressures in the ACI 350.3-06 document has also adopted earlier works from Housner, Veletsos, and Shivakumar. Throughout the years, the code has transformed tremendously, and this study shows that the codes are very similar in many ways, yet their differences can yield significantly different results. Furthermore, the results from the various codes are illustrated using the same example, and the validity of the results are determined as well. The effects on seismic design due to the types of structure, whether the tank is rigid or flexible, and the support system are also introduced; moreover, their absences and the variations in the estimation of seismic parameters in some codes are also shown to have a large effect on the load estimation.

Seismic design of liquid-containing concrete structures

The seismic design of structures is a requirement for any places [sic] where earthquake [sic] occurs, and the design is based upon the codes that vary according to the jurisdictions in which the code was developed for. This study introduces and assesses the document ACI 350.3-06 which was developed by the ACI Committee to guide the design of liquid containing structures, and compares to other codes such as ACI 350.3-01 and NZS 3106 of New Zealand Standard. The importance of liquid containing structures cannot be stressed further, as it is apparent in nuclear applications. The failure of tanks could be due to many reasons: 1) Shell buckling, caused by axial compression due to overall bending. 2) Roof damage as a result of sloshing of the upper portion of the containing liquid due to insufficient provision of freeboard. 3) Failure of inlets and outlets due to their inability to accommodate the deformations of the flexible tank. 4) Differential settlement or failure of supporting soil. The pressures resulted from earthquake [sic] can cause catastrophic disaster, and they [sic] are the impulsive and convective mode which exerts pressures on the walls of the tank. The hydrodynamic model used to estimate these pressures in the ACI 350.3-06 document has also adopted earlier works from Housner, Veletsos, and Shivakumar. Throughout the years, the code has transformed tremendously, and this study shows that the codes are very similar in many ways, yet their differences can yield significantly different results. Furthermore, the results from the various codes are illustrated using the same example, and the validity of the results are determined as well. The effects on seismic design due to the types of structure, whether the tank is rigid or flexible, and the support system are also introduced; moreover, their absences and the variations in the estimation of seismic parameters in some codes are also shown to have a large effect on the load estimation.

Performance-based methodology for seismic assessment of code- conforming RC buildings

<p>The current Indian code for seismic design of structures is based on the force-based design (FBD) philosophy but the damage is more related to strain and displacement rather than strength. Also, structures can’t be designed for target design objectives by FBD method under a specified hazard level. Hence it became necessary to develop new codes and standards based on more robust design methodology to overcome the various shortcomings. The paper presents the results of a study conducted to evaluate the effect of provisions mandated by BIS design guidelines on the performance of a multi-storeyed building in event of a seismic activity. The performance of the building was evaluated on the parameters given in the FEMA guidelines. It was observed that the RC buildings designed as per Indian standard is found to be under-utilized and its overstrength ratio is observed to be of order two, leading to uneconomical design as compared to the building designed according to Performance based methodology for achieving a similar value of the performance level.</p>

Model of Soil-structure Interaction of Objects Resting on Finite Depth Soil Layers for Seismic Design

In case of seismic design of structures the deformability and damping of the soil should be considered, which can be performed in several ways. The infinite soil half space can be approximated with the cone model, which gives constant values for the spring stiffnesses and dashpot characteristics, and an additional mass element for rocking motion. To approximate the dynamic impedance function of a soil layer more complex models were also applied. Most of the methods do not take into account the finite dimensions of the soil, which results significantly different behavior than spring-dashpot systems. To consider the effect of a finite layer a new simple model based on a physical approach is given for the horizontal excitation of strip foundations. Numerical verification is presented, and the parameter range is determined, where the application of the new model is recommended, since applying a spring-dashpot model results in significant errors.

Comparative analysis of normative provisions for seismic design and detailing of reinforced concrete structures

The main objective of this work is to carry out a comparative analysis between the methods and provisions of the Brazilian code ABNT NBR 15421:2006 and those of the ASCE/SEI 7 and the Eurocode 8, on the seismic design of structures. The similarities and differences between these standards, as far as the application of the Equivalent Lateral Forces method (ELFM) and the Response Spectrum method (RSM) are concerned, will be addressed. The responses will be evaluated for a case study that will be modelled by the SCIA Engineer 17 software. This paper also presents some comments on the detailing of reinforced concrete structures to ensure a good performance under seismic loading, allowing for a more favourable interpretation of the seismic analysis results.