CALIBRATION OF LOAD COMBINATIONS FOR EQUAL SAFETY OF CONCRETE MEMBERS

The basic European standard for design of buildings and other engineering works, EN 1990 “Basis of structural design”, provides alternative design procedures and parameters, for which national choice is allowed (Nationally Determined Parameters). One of the most important decisions relates to the fundamental combinations of actions for persistent and transient design situations. It appears that the reliability of reinforced concrete members, designed according to the alternative combination rules provided in EN 1990 by expression (6.10) and twin expressions (6.10a) and (6.10b), may considerably vary. In the presented study probabilistic methods of structural reliability are used to identify characteristic features of both combination rules and to propose a new efficient rule. Expression (6.10) leads to more reliable but less economical structures while twin expressions (6.10a) and (6.10b) provide a lower but more uniform and still satisfactory reliability level (reliability index greater than 3.8 for a 50-year time period). A new combination rule proposed in this study is based on the single expression (6.10) and modified partial factor for variable actions. The proposed combination rule seems to provide even better results than the rule based on twin expressions and has an important advantage of using just one expression. It is further shown that reliability of investigated members depends on reinforcement ratio. Additional calibration studies of reinforced concrete members concerning partial factors of material properties are therefore proposed.

• INTRODUCTION

• FUNDAMENTAL LOAD COMBINATIONS

• RESISTANCE OF REINFORCED CONCRETE MEMBERS

• PROBABILISTIC MODELS OF BASIC VARIABLES?

• RELIABILITY ANALYSIS

• CONCLUDING REMARKS

• REFERENCES