Final answer:
Rafter ties spacing can vary with building design, but must be adequate for roof support. For railroad rails, the necessary expansion gap to accommodate thermal expansion can be calculated using the coefficient of thermal expansion, the original rail length, and the temperature change.
Step-by-step explanation:
Rafter ties are an essential component of a roof's structural integrity and are used to prevent the walls from spreading apart due to the roof's weight or wind load. While the specific spacing of rafter ties may vary depending on building codes and the design of the structure, it's important to ensure they are spaced adequately to provide sufficient support.
Regarding the expansion gap for steel railroad rails, thermal expansion must be considered. When steel heats up, it expands, and if there's not enough space for a rail to expand, it can cause buckling. The appropriate expansion gap would relate to the coefficient of thermal expansion for steel, the change in temperature, and the original length of the rail.
Calculation of Expansion Gap:
To calculate the necessary expansion gap for steel railroad rails that experience a temperature increase of 35.0°C, we can use the following formula: ΔL = α × L0 × ΔT, where ΔL is the change in length, α is the coefficient of thermal expansion for steel (approximately 12 x 10^-6 /u00b0C), L0 is the original length of the steel rail, and ΔT is the change in temperature. A 10.0 m long steel rail will thus require an expansion gap calculated using this formula.