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.

When designing steel structures, one must ensure that local buckling in webs does not take place. This check may not be very critical when using rolled steel sections because

An $$ISMB$$ $$500$$ is used as a beam in a multi-storey construction. From the view point of structural design, it can be considered to be 'laterally restrained' when,

The shear modulus (G), modulus of elasticity (E) and the Poisson's ratio ($$\mu$$) of a material are related as