hey you need differential equations for solving deflection of beams problems,especially very long beam problems cannot be solved without the knowledge of differential equations.(partial differential equations in particular)
Say, I took 4 years of calculus, including differential equations, partial differential equations, theory of elasticity, theory of plates and shells, etc. In those latter 2 courses, the prof used to write partial differential equations that filled up 3 blackboards end to end. One such problem invoved calculating the stress concentration factor at a hole in the center of a plate; after 3 blackboards filled of equations, the answer for that factor was K = 3. So I memorized it. Now in 40 years worth of civil/structural engineering, I have used calculus and diffy Q maybe one or 2 times in my career. The bottom line is that while it is very important to take these calculus courses to get an understanding of what is going on, don't feel like you'll be using them day to day in the Civil Engineering field. Just get the basics down.
Perhaps the test should not be how useful this will be (On the whole, it won't be) ,but whether it is successful in developing in you a way of thinking about appropriate mathematical modelling. There's usually more than one way to solve an engineering problem. In my experience, engineers use the maths they know, and know the maths they use. Even in research situations, if you did have to develop and solve a differential equation, you might be wise to consult a mathematician, especially if it is the case (as it often is in Civil Engineering) that the consequences of failure are risk to life and property.