Beca Structural Engineering
Church College of New Zealand
David O McKay Building
One of two massive trusses between the Gym and Auditorium. You can see the
pillar on the right in the construction photo you have on your web site.
Cross bracing element showing turn buckle for stiffening. Note also the ceiling
hangers and attached blocks. These days they use strapping rather than wire.
The also use gang nails rather than blocks as seen here.
Spacing blocks welded between cross member right angles. Another indication
that the architects and engineers were aware of the need to brace against lateral
loads from seismic events. The blocks multiply the resistance against bending.
These are the cross bracing connections at the bottom of the trusses. The location of
the cross braces also indicate the architect and engineers appreciation for earthquake
strengthening. These braces are more substantial than what is used for today's cross
bracing to meet seismic building codes. Note the spacing of the ceiling joists and even
the boards along the access ways are placed to exact measurement. This is the sign
of "A True Tradesmen" as they say in the Construction business.
This images shows how trusses rest on top of reinforced concrete beams and directly
above reinforced concrete pillars. This indicates the fact that the architect designed the
building to withstand seismic events not just wind loads as implied by the Beca report.
The photo was taken in the ceiling cavity of the David O McKay Building. The bottom of
the trusses are attached to brackets with a loop connection to the inside of the pillars.
This is the bottom bracket. The bracket is welded to the truss. You
can see from this image that the concrete is correctly compacted.
These are the roof rafters. They have are massive measuring 4"x16" they
support the 2"x6" sarking and the ceiling rafters between trusses by way of
number 8 twisted wire. (Now that part is very much a Kiwi tradition that is widely
used in place of strapping, it allows the builders to adjust the ceiling height with
simple turns of the twist thereby giving you a perfect ceiling. These may have
been added later.