Reliability-based updating of bridge abutment safety

Abstract EN

Bridge safety and reliability covers a wide range of applications of modern structural safety / reliability concept and methods to highway bridge engineering practice.

Reliability analysis basically provides accurate estimate of the current strength and the remaining life time for optimum distribution of the available limited resources.

In this paper, the system reliability of cantilever-type abutment is investigated.

Four ultimate strength limit states and two serviceability limit states are considered ; namely, overturning moment, sliding failure, bearing capacity, ultimate moment, excessive settlement and differential settlement limit states, respectively.

Using the closed form of these limit states, first, second order reliability methods FORM / SORM and monte carlo simulation method, MCSM, are used for reliability calculation.

Both reliability index and probability of failure are determined.

The large number of loads, strength and geometrical uncertainties are cut down using some sensitivity analysis.

Both component / individual and system reliability analysis are performed, using COMREL and SYSREL codes, respectively.

The relative importance of random variables as well as the limit states are evaluated.

Moreover, partial safety factors are proposed to achieve desirable safety level in the design.

The effect of the variability of the basic variables on the partial safety factors, the reliability index, and probability of failure are discussed.

The paper shows also how the safety / reliability of the abutment can be updated based on some settlement observations using system reliability analysis.

The present and anticipated reliabilities of the abutment can provide a rational decision making tool to use scarce resources more efficiently.

Some recommendations are introduced for the code of practice.