CONCEPTUAL DESIGN AND CONTROL OF BRIDGE STRUCTURES IN SEISMIC AREAS. Dr Radomir FOLIC , Professor Institute for Civil Engineering Faculty of Technical Sciences University of Novi Sad E-mail: [email protected] INTRODUCTION.
Dr Radomir FOLIC, Professor
Institute for Civil Engineering
Faculty of Technical Sciences University of Novi Sad
E-mail: [email protected]
Taiwan, September 21,1999 SEISMIC AREASTraditional design procedureEarthquake—Structure—Response
Buckling long. bars SEISMIC AREAS
caused by bed
Three steps in design of bridge structures (BS) are:
Three approaches in design of BS are:
Performance requirements depend on the importance and configuration-regularity of bridges (B′s). We can divided (B′s) on:
normal (B′s) & special bridges: arch bridges, cable-stayed B′s, B′s with extreme geometry, and B′s with distinctly different yielding strengths of piers.
Special B′s designed to behave elastically under the design earthquake or use seismic isolation to achieved elastic response.
According EC 8: (BDPh)
in regions of low and moderate seismicity frequently chosen limited ductile behaviour It is needed access for inspection and repair of the pot. plastic hinges and the bearings.
In regions of moderate and high seismicity the ductile behaviour is required.BEHAVIOUR OF BRIDGES IN EARTHQUAKE AND BASIC DEISGN PHILOSOPHIES
The performance-based crit. to provide ductile failure usually require two level design:
Balance mass PHILOSOPHIES
It is recommended that:
require owner's PHILOSOPHIES
approval - ATC
require owner`s PHILOSOPHIES
approval - ATC
Location of primary plastic hinge, a) conventional design, b) menshin-seismic isolation design, c) bridge on a wall type pier (Japan Code 1996)
MODELING AND ANALISYS b) menshin-seismic isolation design, c) bridge on a wall type pier (Japan Code 1996)
Bridge control system – devices, advantages and disadvantages
CONTROL OF STRUCTURES disadvantages
Three-span C. Frame B. disadvantagesS. of MDOF ex. b) Long. Degree of freedom, c) Tran. DOF,d) rotational DOF, e) mode shape I, f) mode shape 2, g) mode shape 3. WITHOUT PROTECTION
Three span bridge with active control system (a); b) B model for analysis; c) SDOF system
controlled by actuator
Controllable sliding bearing for analysis; c) SDOF system
Multi column structures offer the option of fixed or pinned base solutions. Displacements at the deck level are reduced, especially in the transverse direction.
Monolithic connections between deck and abutment are more base solutions. Displacements at the deck level are reduced, especially in the transverse direction.
commonly used for small bridges, solution b) is more reliable
Than of a). Bearing supports have many configurations c) and d).
For both configurations the bearings may be substituted by isolators.
Mechanisms base solutions. Displacements at the deck level are reduced, especially in the transverse direction.
of resisting forces at the abutment
For piers the base solutions. Displacements at the deck level are reduced, especially in the transverse direction.circular section is desirable (L & T demands are similar) provides uniform confinement and restrains the L bars from buckling. In the rectangular sec. the protection of long. bars against buckling must be provided with add. S & tie.