Which type of truss has a curved upper member and a straight lower member?

The type of truss that features a curved upper member and a straight lower member is known as a Bowstring truss. This design allows the structure to effectively distribute loads across a wide area while providing a spacious interior without columns obstructing the space underneath. The curved upper chord of the Bowstring truss acts to handle and transfer the forces of compression, while the straight lower chord resists tension.

This configuration is particularly advantageous in applications where clear spans are needed, such as in large warehouses or gymnasiums, making the Bowstring truss a popular choice in construction for its strength and aesthetic appeal.