Deformation Parameters
In the process of deflection inspection, various clauses in Appendix B of GB
50017-2017 are considered. If you need to consider the provisions of member deflection
in the process of specification inspection and component selection, it can be controlled
by three parameters DFF
, DJ1
, and
DJ2
. The DFF
parameter takes the ratio of span to
maximum allowable deformation as the limit value of deformation, which is called
deflection length
. The flexure length
is the length of the member used
to calculate the local deformation between the two ends. In most cases, the length of
the member is equal to the length of the member. However, in some special cases, the
flexural length
may be different from the member length. For example, the
beam shown in the following figure has 4 nodes and 3 members (in this case, two nodes
are added in the middle of the component). In this case, for all three beam members, the
flexural length
is defined as the total length of the beam. Parameters
DJ1
and DJ2
can be used to define this situation.
At the same time, the connecting line between DJ1
and
DJ2
is also the reference line for measuring the local deflection
of the rod. Therefore, for all three members, DJ1
should be node 1 and
DJ2
should be node 4. If DJ1
and
DJ2
are not defined, the default value of flexural length
is
the length of the member (DJ1
and DJ2
take the end
node of the member respectively), and the local displacement will be calculated along
the line (i.e. axis) of the two ends of the member.
The default setting value of the program is DFF = 400; DJ1 and DJ2 are the end nodes of components respectively. For DFF, you should take the denominator value of the corresponding type of allowable deflection in Appendix B according to the provisions of the code GB 50017-2017, and consider the provisions of other clauses.