Structural assessment and reliability analysis for existing engineering structures, theoretical background

Abstract

The concept presented for the safety assessment of concrete structures integrates nonlinear finite element analysis with stochastic and reliability technology into an advanced engineering tool. The basic aim of the stochastic nonlinear analysis is to calculate the safety index of an existing engineering structure, which characterizes its reliability (and failure probability). The nonlinear solution enables a realistic estimation of the structural response statistics to be obtained (failure load, deflections, cracks, stresses, etc.). The possibility of randomization for such computationally intensive problems is shown. Latin hypercube sampling is used in order to keep the number of required simulations at an acceptable level. Statistical correlation, which is important for a realistic solution, is imposed by using a stochastic optimization technique called simulated annealing. The sensitivity of results to random input parameters can be evaluated using nonparametric rank-order correlation coefficients. The safety index of the analysed structure is calculated from the stochastically obtained structural resistance and expected load distribution using appropriate reliability techniques. The presented approach for the safety assessment of engineering structures supersedes the usual methods based on simplified formulas. It can lead to considerably improved results since the structure is analysed more precisely. Therefore, it supports a higher level of decision-making process in bridge administration and maintenance of transport macrostructure.

Probability and Sensitivity Nonlinear Analysis of the Hermetic Cover of Main Shut-off Valve under Extreme Pressure and Temperature

“…The nonlinear probabilistic analysis of MSV steel covering failure is in accordance with the IAEA requirements [7] and NRC [21,22], experiences from the similar analysis NPP in abroad [20], new knowledges from the probabilistic analysis of structures [2,5,8,9]. Sensitivity analysis of steel plane frames with initial imperfections [9] and our experiences from the previous analysis [12][13][14][15][16][17][18].…”

Probabilistic Nonlinear Analysis of the NPP Hermetic Cover Failure due to Extreme Pressure and Temperature

“…The nonlinear probabilistic analysis of the reactor cover failure is in accordance with the requirements IAEA [7] and NRC [18 and 19], experiences from the similar analysis NPP in abroad [12 and 22], new knowledges from the probabilistic analysis of structures [2-6, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] and our experiences from the previous analysis [12][13][14][15].…”

Zuverlässigkeitsbetrachtung exzentrisch belasteter Stahlbetonstützen

“…Das probabilistische Softwarepaket SARA [8] lieferte die für den Vergleich mit dem Eurocode notwendigen statistischen Widerstandsgrößen. Anhand eines Beispiels lässt sich die Vergleichsführung bzw.…”

“…Wesentlich bei diesen Untersuchungen war, dass das verwendete probabilistische nichtlineare FEM Softwarepaket [8] Die vorab durchgeführten, rein deterministischen Berechnungen dienten der Eingrenzung der notwendigen Anzahl der Lastschritte (inkrementelle Steigerung der Last entsprechend der nichtlineare FEM) zum Erreichen der Traglast. Die passende Wahl der Lastschrittweite und des Lösungsverfahrens (Standard Newton, Arc Length, etc., [11]) war für die folgenden probabilistischen Betrachtungen von großer Bedeutung, da die Simulationen bis in den "Post Peak" Bereich durchgeführt wurden und ein stabiles Verhalten der Traglast erreicht werden musste.…”