Overcoming the drawbacks of the FORM using a full characterization method

• The proposed approach overcomes the main FORM drawbacks.
• The proposed method is more accurate than the FORM.
• The proposed approach is easier to implement than the FORM.
• The computational cost of reliability analysis is reduced.

Although the First Order Reliability Method (FORM) has been widely applied to approximate the probability of failure of engineering systems,it has been observed that FORM presents some serious drawbacks in several situations, such as low accuracy and convergence issues. One class of reliability methods that are able to avoid these difficulties are the full characterization methods. However, these methods are frequently claimed to be complex and to lead to high (sometimes prohibitive) computational cost. In this context, the authors recently presented a full characterization method that is simple to implement and is able to obtain accurate results. Thus, the main goal of this paper is to show that the proposed approach is able to overcome some main drawbacks of the FORM in a practical manner. Two analytical functions as well as three engineering problems were tested, including a truss structure and a water distribution network. In all these cases the full characterization method was significantly more accurate than FORM. Furthermore, the computational cost is comparable to (frequently lower than) that of the FORM.