Given reason for the following is not more than $$20$$ words

(a) A maximum permissible distance between lacing and battens in steel columns is
$$\,\,\,\,\,\,\,$$ usually specified.
(b) It is sometimes preferable to have unequal flange angle with the longer legs
$$\,\,\,\,\,\,\,$$ horizontal in plate girder.
(c) If two channel sections need to be used as a steel column, they may be connected
$$\,\,\,\,\,\,\,$$ 'face-to-face' rather than 'back-to-back'
(d) It is sometimes preferred to have a small gap between the web and the flange
$$\,\,\,\,\,\,\,$$ plate in a plate girder.
(e) A maximum permissible 'outstand may be specific for flange in built-up sections.

A compound steel column consisting of $$2$$ $$ISHB$$ $$400$$ placed at $$320$$ $$mm$$ centers, carries a total axial load of $$2500$$ $$kN.$$ Minimum slenderness ratio of the compound column is $$30.$$ Width of the flange of one $$ISHB$$ section is $$250$$ $$mm$$ and its minimum radius of gyration is $$51.6$$ $$mm$$. Design a suitable single flat lacing. $$20$$ $$mm$$ diameter single rivet is used to connect the lacings to the column. Rivet capacity need not be calculated. The following table may be used.