Horizontal Thrust for a Three Hinged Parabolic Arch
The horizontal thrust for a three-hinged parabolic arch carrying a point load at its crown can be calculated using the principles of equilibrium and geometry.

Equilibrium of Forces
- The horizontal thrust at the abutments of the arch is equal to the horizontal component of the reaction at the crown.
- By taking moments about the hinges, the horizontal thrust can be determined.

Geometry of the Arch
- The shape of the arch is parabolic, which means the load is distributed along the curve according to the parabolic equation.
- The point load at the crown can be considered as a concentrated load acting at a specific point.

Calculation of Horizontal Thrust
- By considering the geometry of the arch and the distribution of the load, the horizontal thrust can be calculated using the equations of equilibrium.
- The horizontal component of the reaction at the crown can be determined by resolving forces horizontally and taking moments about a point.

Conclusion
- The horizontal thrust for a three-hinged parabolic arch carrying a point load at its crown can be calculated by analyzing the equilibrium of forces and the geometry of the arch.
- By following the steps outlined above, the horizontal thrust can be accurately determined for a given arch configuration and loading condition.