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# Concrete column and steel beams

• To: seaint(--nospam--at)seaint.org
• Subject: Concrete column and steel beams
• From: "Ashraf Manjappara" <ashraf.manjappara(--nospam--at)gmail.com>
• Date: Sat, 20 May 2006 16:11:47 +0530

Dear All,
I am designing a building of 106x60 m in plan size and maximum 17m
height with roofs at different levels. The columns are of concrete and
most of the beams are of steel . Roof is of steel deck type. I have about
7 braced frame in the x-direction (106m is in x-direction). The span of
frames vary from 10 to 22m. In the y-direction there are 7 columns @ a
spacing of 10m. Only 3 bays are braced. The height of braced bay is 8m
and span is 10m. Based on the client drawings we developed the STAAD
model. We modeled K-braces in the STAAD model. All connections are taken
as moment connections. The braces are taken as Truss member.
I've the following issues and doubts.
1. The brace member length is almost 10m. Is it realistic to go for such
lengths?. What is the maximum length we can go for K-brace members
?.What is the best section such as angle etc for braces?. I have very
high axial forces on the braces about 112KN in compression. The steel
beams used are of W460x60(SI units). Whether the stiffness of beam has
great influence on axial force on braces?. Is K-braces are efficient
comparing other bracing systems?.
2. What is the best way to connect braces to concrete columns?.
3. I considered wind loads on windward walls, leeward walls and on roofs
as per ASCE?. Is it right?.
4. What is the best way of connecting steel beams to concrete columns?.
Also in multistoried steel structures which is the best connection for
beam to beam such as moment or non-moment?.
5. The client specification says temperature effect should be considered
for +/- 25 degree Celsius. But in braces with such a temperature change
very high axial forces are developing. What is the best way to reduce
the temperature effects ?.
Sorry for the fact that this message is very lengthy.
Any feedback is highly appreciated?.