Pile Integrity and Load Testing: Methodology and Classification

Cosic M., Bozic-Tomic K., Susic N.: Pile Integrity and Load Testing: Methodology and Classification (presentation)

The presentation shows the methodology and classification of pile integrity and load testing, in compliance with current foreign standards, as well as our own defined segments of standard improvement and our own definitions of certain key elements. The classification has been conducted according to the test types which clearly define the pile testing process, analysis methods, and test results processing. Beside the basic division of pile testing to integrity tests and load tests, there is also an additionally defined group of shaft control tests in the case of bored piles, since for the proper shaft formation, when it comes to bored piles, certain qualitative-quantitative criteria must be fulfilled beforehand. Presented in this way, the methodology and classification of pile integrity and load tests serves, primarily, an educational purpose for civil and geotechnics engineers who deal with this issue, to additionally introduce innovations in this field of testing and and clarify all the elements of the testing since contradictory opinions and disagreements regarding the testing details are quite common in practice.

Probabilistic Analysis of Bearing Capacity of Piles

Cosic M., Susic N., Folic R.: Probabilistic Analysis of Bearing Capacity of Piles (poster)

The poster shows a probabilistic concept for determining the pile bearing capacity, taking into account the variability of CPT test parameters (stochastic simulations) and methodology of calculation according to the requirements of Eurocode 7. Solutions obtained using this approach were compared with those obtained from the static load test (SLT).

Bridges: Nonlinear Analyses, Probability Theory and Optimization Theory

Cosic M., Folic R., Folic B.: Bridges: Nonlinear Analyses, Probability Theory and Optimization Theory (poster)

The poster shows a multidisciplinary approach to the assessment of seismic performances based on the Performance-Based Earthquake Engineering (PBEE), taking into account the multi-criteria optimization theory in analyzing the priority methods for bridge rehabilitation/strengthening. One bridge model was subjected to nonlinear static pushover analyses (NSPA), target displacement analyses using the spectrum capacity method (CSM), vulnerability analyses, and reliability analyses, while for a damaged bridge, in addition to be considered using the above methods, was also analyzed using the VIKOR method of multi-criteria optimization.

Pile Tests

Cosic M., Folic R., Susic N.: Pile Tests (presentation)

Based on the analysis of a large number of scientific papers, the authors of this presentation show their own classification pile tests. The general classification is conducted using high strain and low strain tests, i.e. tests whose basic purpose is to determine the capacity of piles and tests the purpose of which is to analyze the integrity of piles. The pile capacity and integrity tests are critically analyzed by defining their advantages and disadvantages using in-situ investigations, cost effectiveness, requirements regarding the special education of engineers, the quality of data obtained, complexity of data processing and the quality of the processed end results. The proposed classification of pile capacity and pile integrity tests enables to identify very effectively which is the optimal test type for further geotechnical analysis of structures and which type of test should be used in the phase of geotechnical testing for designing and scientific research.

Soil-Pile-Pier Interaction

Cosic M., Folic B., Folic R., Susic N.: Soil-Pile-Pier Interaction (presentation)

The purpose of this presentation is to show the methodology for performance-based seismic evaluation of soil-pile-bridge pier interaction using the incremental nonlinear dynamic analysis (INDA). The INDA analysis was post processed separately for the pier and for the pile, so that the constructed PGA=f(DR) curves are in the capacitive domain. For these curves the authors identified the IO, CP and GI performance levels, while the regression analyses were conducted based on the specific DR and PGA parameters. Fragility curves were constructed based on the solutions of regression analysis and the probability theory of log-normal distribution. Based on the results of fragility analysis, reliability curves were also constructed.

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.

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