Development of Ground Motion Record Surface and Response Spectra Surface

Cosic M., Brcic S., Susic N., Folic R., Bozic-Tomic K.: Development of Ground Motion Record Surface and Response Spectra Surface (presentation)

The presentation shows a mathematical formulation of an originally developed ground motion record surface (GMRS) and response spectra surface (RSS) for the presentation of 2D seismic ground motion records (GMR) and the corresponding response spectra (RS), respectively. These surfaces are constructed by transformation from 2D polar coordinate system to a 3D cylindrical coordinate system and then to the 3D orthogonal coordinate system. The principle of application of three orthogonal coordinates for each discrete value is used in order to achieve easy manipulation and interpolation of spatial surface. Scaling of accelerograms was carried out using two procedures: the Least Square Method (LSM) and Spectral Matching (SM).

Performance-Based Nonlinear Seismic Analysis

Performance-based nonlinear seismic analysis

Cosic M.: Performance-Based Nonlinear Seismic Analysis (presentation)

The presentation shows a part of the developed theoretical formulations and results of numerical analyses conducted in doctoral dissertation, which is defended at the Faculty of Civil Engineering University of Belgrade in 2015. In summary volume presents the research in the field of:

– ground motion records and response spectras,

– research in the field of non-linear responses of frame system that participate in the structural system of frame buildings,

– research in the field of non-linear response of the 3D model of frame buildings,

– research in the field of relations of the 3D model of frame buildings response/seismic demand.

Nonlin Quake software

Cosic M., Brcic S., Folic R., Susic N.: Nonlin Quake Software (presentation)

The presentation shows the original developed software NonlinQuake for performance-based seismic analysis of 3D structural models. Software Nonlin Quake consists of several independent compatible softwares that implements: create a database of two componential ground motion records (GMR), generation and processing of multicomponential GMR, creating incomplete and complete nonstationary artificial accelerograms, deterministic and probabilistic seismic hazard analysis, generation and processing of multicomponential response spectras, analysis of design parameters, processing of pushover curves and surfaces, calculation based on hybrid incremental nonlinear static-dynamic analysis, target displacement analysis, analysis and scaling of response spectras and analysis of target displacement envelope. For four considered methods for analysis of system performances: nonlinear static pushover analysis (NSPA), incremental nonlinear dynamic analysis (INDA), incremental dynamic analysis (IDA) and hybrid incremental nonlinear static-dynamic analysis (HINSDA), flow charts are shown.

Damping Models

Folic R., Cosic M., Folic B.: Damping Models (presentation)

This presentation shows the aspects of damping modelling in structural analysis through the systematization of damping types and flowcharts, depending on the type of analysis applied: linear and non-linear, static and dynamic. Damping has been systematized based on the way it was introduced into calculations, i.e. over material damping, link element damping and damping directly introduced into the analyses which are conducted in capacitive, time and frequency domains. In the process of creating numerical structural models, the type of damping and the way of its introduction into structural analysis can be very efficiently selected by applying the flow charts developed. By applying the developed flowcharts, alternative approaches to the introduction of damping into structural analysis can also be defined.

Soil-Pile-Pier Performance

Cosic M., Folic B., Folic R.: Soil-Pile-Pier Performance (presentation)

In the presentation is shown a discrete numerical solid pile model with a discontinuity and defects. Model included performance-based seismic evaluation of the soil-pile-bridge pier interaction. The pile discontinuity and defects are modelled by reducing the specific finite elements and elastic modulus of concrete. The wave-propagation response of the pile was analyzed based on a step-by-step numerical integration using the Hilber-Hughes-Taylor (HHT) method in time domain (THA). The response analysis is performed with an integration of individual reflectograms into a reflectogram surface, which is generated in a 3D cylindrical coordinate system. Non-linear response of the system is considered using the incremental-iterative Newton-Raphson`s method, while the stability analysis is performed according to the modified geometrical nonlinearity analysis of stability. Determination of critical load and effective length of the pile are performed based on numerical solution and using regression analysis of the power function. The procedure of the soil-pile-bridge pier performance evaluation is based on the incremental nonlinear dynamic analysis (INDA). The system’s input signal is treated through the generated artificial accelerograms, which were subsequently processed by soil layers and for the bedrock. Fragility curves were constructed based on solutions of the regression analysis and the probability theory of log-normal distribution, while the generation of reliability curves is based on a solution of vulnerability.