00711738

Component

http://onlinepubs.trb.org...onf/1995/cp7/cp7v2-033.pdf

A framework for considering redundancy in the design and load capacity evaluation of highway bridge superstructures is proposed. Redundancy is defined in terms of the capacity of the bridge system to resist failure at high loads and to resist system serviceability distress compared with its capacity to resist first member failure. The consequences of damage of one member to the overall system capacity is also checked. The proposed framework consists of tables of load modifiers that can be used to assess the redundancy level of typical bridge configurations. The load modifiers are used during the design process to require that members of less redundant configurations be more conservatively designed than is allowed by current standards. On the other hand, highly redundant designs are rewarded by permitting less conservative member designs. For bridges with nontypical configurations that are not covered by the tables, a direct analysis approach is recommended. General guidelines explaining how to perform such an analysis are provided. These include the loads that should be applied, the limit states that should be checked for both intact and damaged conditions, and the target load factors that the bridge should sustain before these limit states are violated. System factors that provide a measure of the system's redundancy can be calculated from the results of the incremental analysis. The load modifiers obtained from the tables and the system factors obtained from the incremental analysis can be used for the design of new bridges or they can be used to calculate rating factors for the evaluation of existing bridges. Thus, bridges with lower levels of redundancy must have their member capacities increased or they will have lower ratings. An example illustrating the proposed procedures is provided.

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00711666

English

p. 338-348

1995

Transportation Research Board Conference Proceedings

Fourth International Bridge Engineering Conference

0309061091

Figures (3) ; References (5) ; Tables (4)

Bridge superstructures; Conferences; Guidelines; Highway bridges; Loads; Redundancy; Structural analysis; Tables (Data)

Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls

TRIS, TRB

Sep 6 1995 12:00AM