KVPT’s Patan Darbar Earthquake Response Campaign - Work to Date - September 2016

6. Wall Plate Detailing
Description
Brick masonry walls are typically topped with wall plates
on both the inner and outer faces of the brick masonry
walls. The wall plates form a ring around the wall
with half-lap joints connecting the intersecting wooden
members. Theys are also used to connect other wooden
elements within the structure.
Issues
The wall plates in their original layout are very susceptible
to dislodgement during an earthquake, as they are
independent of one another and not properly tied back
to the brick masonry wall itself. This means that during
an earthquake, the two wall plates, resting on different
areas of the brick masonry wall, may shake independently
and contribute to the pulling apart of various timber
connections within the structure. Thewall plates could
be a vital element within the structure to tie the brick
wall and timber structure together, but were traditionally
not detailed to do this.
Options for Seismic Strengthening
To improve the seismic behavior, connection should be
established through the brick wall to prevent dislodgement
of the wall plates. If inner and outer wall plates are
properly joined through the wall, they will act together
as a stiffer frame element at the top of brick walls and
will help the building to shake together as one unit at
this location. This improved continuity can be established
by extending the inner wall plates to the outer
wall plate to create added stiffness in the corners, adding
intermediary wooden ties through the walls to connect
the wall plates along the wall, and bolting steel plate connections
in the corners to increase the tensile strength of
the joints and allow ring action. These interventions will
both strengthen the timber frame and reduce bulging
and blowouts within the masonry walls.
C
B
D
D
A
E
F
F
Top
Typical wall plate construction in
Newari brick masonry walls. The
inner and outer wall plates are very
often not connected through the
brick masonry.
Middle
Updated detail which extends inner
wall plates to join to the outer
wall plate, creating a stiffened ring
beam. The outer wall plate is also
reinforced with bolted steel angles
at the corners to further strengthen
the frame.
A. Outer wall plate
B. Inner wall plate
C. Wall
D. Dovetail connection or half lap
joint between wall plates
E. Metal corner plate to tie wall
plates together
F. Corner half lap joint
Bottom
Uma Maheswor Temple, Kwalkhu.
Implementation of strengthening
(1992).
(Letters indicate same elements as in
image above.)
F
B
A
C
61