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[spsvasan at eth.net]

Hello everybody,

(A) Comparison of Clauses 4.3.5.1 and 7.3.3.1 in Draft IS:800

The clauses 4.3.5.1 and 7.3.3.1 are very similar. But clause 7.3.3.1 is
more elaborate and covers two more cases, viz, roof truss bearing and
column web connection. Is there any reason for omitting these two cases in
clause 4.3.5.1?

(B) Notional Horizontal Loads in Draft IS:800

The notional horizontal loads (Clauses 4.3.6, 4.1.2), and 5.5.1.2) are
mentioned only regarding sway stability of the frames. Am I correct in
assuming that notional horizontal loads need not be considered in strength
check? If they are to be considered only for sway stability check, the load
factor should be 1.0?

(C) Minor typo errors in Draft IS:800

(1) Table 7.2: Welded box sections: second expression below "Thick welds
and" should be "h/tw" instead of "d/tw"

(2) Clause 7.5.2.2: The term "7.5.2.1" should probably read as "7.5.1"


(D) Comparison of Clauses 4.3.5.2(b) and 7.3.3.2

Clauses 4.3.5.2 (b) and 7.3.3.2 are similar, but, in addition, clause
7.3.3.2 permits simpler (?) equal division of joint moment to upper and
lower columns. I think the provision regarding equal distribution of joint
moment to upper and lower columns is not necessary. In any case,
(MI/length) has to be calculated to check whether this equal distribution
is permissible. Once we have I/l values it is easy to apportion the joint
moment in proportion to their stiffnesses, which is more accurate..

(E) Clause 7.4.2.3 in Draft IS:800

The clause 7.4.2.3 gives the minimum size of base plate below stanchions.
这s clause is present in the 1984 code also. I do not understand the
necessity of this provision. Is anything wrong in adopting smaller base
plates, if the load transfer between stanchion and pedestal is otherwise
proper?

(F) Table 7.6 in Draft IS:800

Table 7.6 pertains to the design of single angle struts.

(1) The constants k1, k2, and k3 depend upon the "gusset/connecting member
fixity". The table gives values of the constants for fixed and hinged
conditions. The note below the table indicates that intermediate values are
to be adopted based on the "Stiffness of in-plane rotational restraint
provided to the gusset/connecting member" Is there any reference showing
how to calculate the stiffness of gusset/connecting member? Let us consider
a truss. In calculating the in-plane rotational stiffness of the gusset
plate, where do we apply the load or loads? How do we account for the
flexibility of the top or bottom chord to which the single angle strut is
connected? What value of [(gusset stiffness) / ( strut stiffness)] will
entitle us to assume fixed end condition?

(2) There seems to be a typo in this table. The second value below k3
appears to be incorrect.

(G) Clause 7.6.1.5 and 7.7.1.4 in Draft IS:800

The two clauses 7.6.1.5 and 7.7.1.4 deal with the increase in effective
slenderness ratio for laced and battened columns due to shear deformation
effects.

I wish to know whether the shear deformation effect affects only global
slenderness ratio of the column or does it also affect the local
slenderness ratio of the column?

Regards
S.P.Srinivasan

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