1 Effect of Reinforcing Steel Bars
When concrete is reinforced by a regular grid of reinforcing bars, it is often appropriate to consider concrete with the bar grid as one heterogenous composite material which is macro-homogeneous on a larger scale. Obviously, in such a composite, the bars inhibit the formation and propagation of cracks. If there were no bond slip, then the opposite faces of a crack would not be able to open apart, and so there would be no fracture until the bar breaks. This simple consideration immediately clarifies that bond slip must take place and must be taken into account. The property which matters is the stiffness of the connection provided by the steel bars between the opposite faces of the crack or crack band.