Dear Bidnu,

Yes, Physics is an integral part of Civil engineering, Using the concept of moment and force balance, bending moment and shear stress is determined. According to value of bending moment and shear stress further designing of member is done like how much cross section, steel, clear cover etc is required. So basically the force or moment balance is the basic physics that civil engineering apply for determining the stresses/moment at each member.

You can also refer to the syllabus of NIT's.

Hope this helps.

All the Best!!