CONTENT 5.1 SEISMIC BEHAVIOUR ... - CIB-W18

(7) The ductility factor of the braced frames which agree with the above
items should be 2.0 in average or 1.5 considering the variation. The
ductility factor of other types of braced frames should be 1.0.
(8) It is possible to obtain the "q" value information from if the soil profile
is determined.
23-15-5 A Ceccotti, A Vignoli
On a better evaluation of the seismic behavior factor of low-dissipative
timber structures
Summary
Some results concerning the seismic verification of w-dissipation timber
structures designed according to Eurocode assuming a behaviour factor q
= 2 are given in this paper.
The semi rigid connection design was performed considering suggestions
given by the Authors in a previous paper.
The numerical simulation was carried out using a time domain non linear
dynamic analysis .
Introduction
Three kinds of timber structures are considered in the draft version of Eurocode
8:
– non-dissipative
– low-dissipative
– medium-dissipative.
But due to the lack of knowledge the value of the behaviour fact reducing
design inertia forces ("q") was fixed uniformly equal to 1 for each kind of
structure.
Conclusions
From this research it seems possible to state that designing low dissipation
semi-rigid connection portal frame timber structures following EC 5 and
EC 8 rules but assuming q = 2 and using simple dimensioning rules for
semi-rigid joints, it is possible to obtain structures whose resistance easily
fulfils the Code strength requirements for seismic zones.
23-15-7 M R O'Halloran, E G Elias
Performance of timber frame structures during the Loma Prieta California
earthquake
Cib structural timber design code
The CIB Timber Code provides for the development of design procedures
for timber components and special structures. Section 7.4 is intended to
provide specific provisions for the development of bracing requirements.
Currently, the draft code does not contain references to either standard
methods of test, sampling, or analysis of test data reporting wall bracing or
diaphragm action.
Objective
The purpose of this paper is to present a review of the structural performance
of timber frame buildings following the 1989 Loma Prieta earthquake.
Results of this inspection reinforce the need for standardization in
design of timber frame structures to resist seismic loading.
Summary and conclusions
A team of engineers from the American Plywood Association
(APA)visited the San Francisco Bay area shortly following the Loma Prieta
earthquake of October 17, 1989. Damage from the earthquake occurred
in scattered locations within the region. Within these locations, the heaviest
damage appeared to be to buildings with unreinforced masonry walls.
All observed wood-framed buildings which were damaged were either
built before the 1973 Uniform Building Code introduced updated earthquake
regulations, or incorporated critical construction features but with
inadequate connections, or other features which were not nailed or stapled
in accordance with minimum code requirements.
It is the conclusion of the APA team of observers that framed construction
built to meet current provisions of the Uniform Building Code performed
very well. No code deficiencies for this type of construction were
observed. However, greater attention must be paid to design and installation
of connections and fastenings, and to structural continuity, especially
in small buildings which may not be engineered.
CIB-W18 Timber Structures – A review of meeting 1-43 5 SPECIAL ACTIONS page 5.11