1 / 9

Bridge

Bridge. A bridge is a structure that connects two roads across a waterway. Head losses occur while water passes through the bridge between its walls. Head losses should not exceed 10 cm. ≤ 10 cm. Water depth d. Longitudinal section in a bridge. B. 0.75 m. S. d. b.

geri
Download Presentation

Bridge

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bridge • A bridge is a structure that connects two roads across a waterway. • Head losses occur while water passes through the bridge between its walls. • Head losses should not exceed 10 cm.

  2. ≤ 10 cm Water depth d Longitudinal section in a bridge.

  3. B 0.75 m S d b Cross section in a bridge

  4. Hydraulic Design • Hydraulic design is conducted to obtain the number of vents (n) and the span of the vent (s) • The selection is made such that the head losses does not exceed 10 cm. • A simple design can be achieved following the next steps:

  5. Assume n, then calculate S as follows: • Adjust S to a practical value (S ≤ 5.0 m) • Calculate the velocity through the bridge Where Q is the discharge in m3/sec, V is the velocity in m/sec and Aw is the water area.

  6. Aw = n . S . d Where d is the water depth. • Head losses is calculated as follows Where Hl is head loss (m), g is gravitational acceleration (9.81 m/sec2), C is a constant.

  7. C = 0.72 for S ≤ 2.0 m • C = 0.82 for S ≤ 4.0 m • C = 0.92 for S > 4.0 m

  8. Example: Design a bridge across a waterway having a discharge of 18 m3/sec. The bottom width is 15 m and the top width is 21 m and the water depth is 3 m. • Sol. Assume n = 5 S = (21-3)/5 = 3.6 m Aw = (15+21)/2 * 3 = 54 m2

  9. v = 18/54 = 0.33 m/sec Av= 5 * 3.6 * 3 = 54 m2 Check of Heading Up Since Aw = Av .. Hu = 0 Hu < 0.1 m … OK

More Related