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

aside for aesthetic reasons and because the introduction
of a new structure woven through the traditional framework
of the building would limit access to the central
core and throughout the structure.
Option 3
This option investigated joining sound existing timber
with new timber at its rotten base, and encase the timber
columns with hollow steel section from just above the
resulting timber joint down to a slab or grillage foundation.
The structure above the ground floor arcade would
then be reinforced with timber beams and steel collars
at the intersections of the central core columns. Small
solid steel tension rods would then act as cross bracing at
the ground floor to connect the steel reinforcing on central
core columns. This option would result in the potential
to keep the historic timbers in the structure, and
the visibility of these timbers would not be inhibited.
There would, however, be steel tension rods installed to
provide a secondary load path for lateral loads that pull
against the building, allowing these loads to be pulled
back down into the foundation.Visibility through the
timber arcade would be slightly disrupted by the cross
bracing, and access to the central core of the structure
would be impeded. This option would not be viable at
the Manimandapa North, because the central core of
the structure is used for religious puja. Additionally, the
historic timber elements would still be used for gravity
loads, so it would be a composite system whose connections
and geometry of cross bracing would be more
difficult to determine and implement. The complexity,
difficulty of implementation, and visibility of this system
rendered it nonviable for the current situation.
Option 4
A later option involved joining sound existing timber
with new timber at column bases, encased with a fitted
steel shoe that slides onto the base of the timber column.
This shoe would be either embedded into a slab or bolted/welded
to a grillage foundation, and would allow for
embedded dowels to secure the timber column. Ensuring
that the shoe fully covers the timber joint, the wood
would be routed at the edges to leave the timber column
and the steel faces flush. The columns would then also
be connected to a grid of horizontal timber beams just
above the open arcade to stiffen them by shortening the
span. The intersections of these beams would be reinforced
with steel angles, and dowels would pin the columns
at this point. This way, the main architectural feel
and appearance remain intact, wood joinery and base
connection are strengthened against lateral loads, and
we are able to keep the historic timbers in the structure.
This allows for a flexible system, utilizing mainly timber
framing in the upper structure, with reinforced connections
and a stable foundation to limit vibrations. This
option would be a compromise structurally, but would
still be a significant improvement in safety and stability
over the original construction.
The design compromise that was chosen evolved from
Option 4 as described above. With a base foundation
utilizing a reinforced concrete slab with cruciform shear
key as its base, this would aid in the establishment of a
damp proof course. The columns and base stones would
have direct positive structural connections down to this
concealed concrete slab. This would provide resistance
against the pullout seen at these connections during the
Above Left
Development of a stainless steel
shoe detail for the base connection
of the central core timber columns
to a concrete foundation. This
involves a steel base plate recessed
into the concrete with predrilled
holes. Stainless steel rods would
then be embedded into structural
epoxy in drilled holes in both the
timber column and the concrete
foundation. A simplified construction
method was developed to prefabricate
the shoe and to use it as a
template to ensure proper location
and alignment of the anchor holes.
Above Right
Section detail (plan view) showing
the connection of new horizontal
timber beams atop the columns
with reinforced joints and a dowel
(embedded in structural epoxy)
connecting the central core column
to the beams to stiffen the system.
Both sketches by Evan Speer, July 2016
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