office of structures manual for hydrologic and hydraulic
Contents
1. 11215577 1067538562 10003454 ab5u ngz s 5 7014z GUTES 5799459 4715176 S465251 1319725 641655 554779 524198 TO J Wa BRM Wow ke ah Ps mein eo m Te WO Ps Flow Area av s 588 588 528 588 588 525 578 5568 555 549 538 525 518 510 500 490 481 471l 462 445 436 428 420 412 405 398 391 au eu 43 ol 10 33 5l 69 10 33 7 28 93 Remark deri ft APRIL 2011 Page 16 Please note that the highest flow velocity of 6 9 fps occurs at time 7 6 hours underlined row above when the downstream tide elevation 16 at an elevation of 0 84 feet The channel bed elevation 15 at 6 8 feet so the downstream flow depth 15 computed as 7 6 feet Surface and subsurface boring samples indicate that the channel bed 1s comprised of a medium sand with a D50 of 0 0016 feet Clear Water Scour Equation vo from TIDEOUT output 4 Vs Yo V5 Y Yo from char t Contraction Scour Flow Depth q Vo Contraction scour Depth Ys7 Y Yo The values of vo 6 9 fps and yo 7 6 feet are known values obtained from the TIDEROUT output tables and the value of 215 the total scour depth we wish to calculate This missing variable 15 Vc the critical velocity of the sand which can be obtained from the chart below excerpted from the ABSCOUR 9 Users Manual For a flow depth of 7 6 fe2. Graphic Ti initrd Hal ben arta Fable as elimiborn ane Gebers ascending onder Data Surlaca Area cam A Insert rw j 5510010 nrw 2 10500000 Delete row 4 d 18000000 19 19000000 i 1 i 1 E J io 1 I i3 1712 1 114 um j IL LLLI The user creates a storage area rating table for the tidal basin upstream of the bridge using the Tidal Basin card Beginning with the elevation of the channel bottom at the bridge usually a negative value below zero the information 1s provided as a set of elevation area pairs The areas corresponding to the elevations can be obtained by measuring the areas between successive contour lines See F 1 help The upper limit of the rating table should be selected as an elevation above the design storm tide elevation The area contained within a given contour line can be measured with a planimeter or can be computed using appropriate software 1 e GIS Systems CADD Programs topographic digital elevation models etc APRIL 2011 Page 8 BRIDGE WATERWAY OPENING DATA 2566 TIDEROUT2 C X2008 old stuff on tidal hydraulicsXZ008 fred tidal presentation EXAMPLE 1 4 11 08 119 PELLE File
3. The user will need to convert tidal data from the NGVD datum to NAVD datum when using the program See Chapter 10 Appendix A Various other factors such as the wind may influence the flow through the bridge Please refer to Chapter 10 Appendix A for a discussion of these factors INPUT DATA FOR TIDEROUT 2 Typical input values are described below The user may wish to select other values depending on the issues to be addressed APRIL 2011 Page 4 TIDEROUT 2 C V2008 old stuff on tidal hydraulics 008 fred tidal presentation EXAMPLE 1 4 11 OB tid Fille Run Draw Tools Help Project Data Stream Flow data Tidal Basin Data Bridge Opening Data Roadway Data Output Graphic Project WALLACE Creek no wind setup 321 span overtopping 100 wr 4 01 2008 Unit English units soo scs Analysis starting time hry 0 Analysis ending time 12 Time step ihr E starting bridge headwater elevation im 5 24 Leave blank far default condition Press F for detail Tidal amplitude 313 Mean tidal elevation 211 Tidal period ihr 24 DISCLAIMER Tidal Peak Time 0 TIDEROUT 2 opens to the Project Data Card This card has the following characteristics I TOOL BAR File File management including accessing and saving TIDEROUT 2 files Run Run the program Draw Draws a schematic of the output results Tools Utility tools for quick calculations Help
4. 3135 22 32 50 0 2888 13000000 0 S36 00 0 80 5 172 5 2 474 62 SO 96 1 204 13000000 0 588 0 1 00 5 133 5 175 527 98 155 65 1 497 19000000 0 588 n l z 5 087 5 l4z 622 54 265 15 1 765 13000000 0 68 00 1 40 8 032 amp 102 708 16 375 58 z 007 13000000 0 588 0 1 60 4 5969 5 053 785 19 511 95 2 2426 13000000 0 588 0 1 80 4 893 4 997 954 45 657 22 2 422 13000000_ 0 588 n 2 00 4 821 4 9832 916 93 207 70 2 599 19000000 0 588 00 2 20 4 735 4 560 972 70 357 74 13000000 0 588 0 2 40 4 642 4 780 1025 54 1109 41 2 307 19000000 0 588 n 60 4 542 4 692 1073 00 1257 99 3 041 19000000 0 555 00 2 80 4 436 4 597 1116 71 1403 00 3 165 13000000 0 S66 00 3 00 4 323 4 496 1156 01 1528 75 3 282 13000000 0 588 0 3 20 4 204 4 391 1700 28 1609 98 3 402 19000000 0 588 n 2 40 4 050 4 251 1246 07 1671 12 23 5322 13000000 0 68 00 3 60 3 350 4 168 1296 09 1708 24 3 674 13000000 0 588 0 3 80 3 815 4 050 1347 54 1787 06 3 820 13000000 0 588 0 Time Tide EL Basin EL Bridge 0 Weir Q Bride V Basin Area Flow Area RBemark thre cfs cts tits sf av f deri iti 4 00 3 675 3 925 1594 72 1582 52 3 953 lS5686z2596 z2 558 00 4 20 3 531 3 794 1434 33 1943 29 4 066 18134795_2 558 00 4 40 3 393 3 656 1465 65 1972 59 4 154 l 755
5. Help menus to answer questions about the program F 1 Short Help Help for any input window can be obtained by placing the cursor in the input field window and clicking on the F1 Key 2 TAB BARS A PROJECT DATA e Project Describe the highway and the estuary being crossed include information on particular aspects of the study 1 flood discharges referenced tidal station etc e Unit option SHA prefers English units e Analysis starting time For the Chesapeake Bay the storm tide period is assumed to be 24 hours Typically the worst case scour is expected to occur during the 12 hour ebb tide period starting when the tidal basin 16 full high tide and at the elevation of the design APRIL 2011 Page 5 storm tide time 0 hours and ending when the basin has emptied time 12 hours e Analysis ending time 12 at low tide e Time step See e Starting bridge headwater elevation High tide elevation of the design storm tide or See F1 guidance e Tide amplitude See e Tidal period Default value 15 24 hours e Tidal peak time hrs is Zero Please click on and read the Disclaimer button STREAM FLOW DATA TIDEROUT 2 C V2008 old stuff on tidal hydraulics 008 fred tidal presentation EXAMPLE 1 4 11 0OB tid File Run Draw Tools Help Project Data Stream Flow data Tidal Basin Data Bridge Opening Data Roadway Data Output Graphic iil Constant Flow Discharge cfsicms Dg t Given H
6. to import TIDEROUT2 output into ABSCOUR to compute pier scour Introduction Chapter 10 Appendix A Hydraulics of Tidal Bridges provides a comprehensive discussion of various aspects of the hydraulic design of tidal bridges The user of the TIDEROUT 2 program is encouraged to become familiar with the guidance in Chapter 10 Appendix A before conducting a tidal analysis at a bridge The user needs to recognize that unsteady tidal flow 1s complex and that TIDEROUT 2 provides for simple hydraulic and scour models to evaluate it Nevertheless the program can be used effectively in the design of structure foundations to evaluate and determine worst case scour conditions Tide Models The Office of Structures currently uses TIDEROUT 2 and HEC RAS to analyze tidal flow at a bridge Two dimensional flow models are useful for evaluating flow in large estuaries but are not considered necessary for the typical SHA tidal crossing The SHA guidance 15 geared towards tidal areas tributary to the Chesapeake Bay Special studies may be necessary for estuaries discharging directly to the ocean The following guidance is provided with regard to selection of a tidal model for Chesapeake Bay estuaries Most likely a typical bridge site will not exhibit the clear cut categories listed below and judgment will be needed to select the most appropriate model In some cases it may be helpful to use both models compare the results and then select the most appropriate res
7. 5526 3 588 0n 4 60 3 232 3 512 1459 67 1973 55 4 222 le8952047 588 0n 4 50 3 077 3 365 1508 54 1978 10 4 277 16331143 4 558 00 5 00 2 320 3 221 1528 80 1633 63 4 351 l5726382 5 585 6 5 20 2 761 3 085 1556 27 1381 97 4 484 15155474 9 578 43 5 40 2 600 2 952 1593 09 1158 37 4 668 l4en0 0292 9 568 81 5 60 2 437 2 825 1538 35 3186 68 4 884 ld4n amp e5 d3 3 559 10 5 850 e zd 2 708 1695 81 572 10 5 145 13573553 9 549 33 6 00 2 1180 2 600 1755 81 257 25 5 455 l3119 712 z 539 51 6 20 1 546 2 494 1836 93 94 94 5 780 l 673790 4 529 69 6 40 1 783 2 394 1597 47 11 897 6 083 12214771 7 513 287 6 60 1 620 2 263 1941 85 00 6 345 ll729334 89 10 6 850 l 453 2 147 1969 09 00 6 559 llzl15577 7 500 39 7 00 1 300 2 018 1980 62 Oo 00 6 726 l e7386z2 0 490 77 7 20 1 143 1 881 1977 36 00 6 848 l nn s4s4 481 28 7 40 0 9385 1 736 1959 11 00 6 9139 az75724 471 93 7 60 0 837 582 18 5 33 00 6 3934 500203 5 462 76 7 80 l 0 00 6 887 FIRE TET Vic EET 2 00 0 545 l 239 1805 58 00 6 766 eG77B52297 z2 445 02 Ss 20 0 405 1 045 1715 94 00 6 552 5799459 0 436 51 8 40 0 270 0 829 1595 84 00 6 210 47151276 3 476 27 2 60 0 140 0 581 1430 26 00 5 8671 3468251 1 420 31 8 80 0 016 0 272 1173 16 00 4 738 19197286 412 58 9 00 1 03 O 115 682 75 00 2 80 541655 6 405 37 9 20 O 216 O 200 83 44 00 0 349 534779 3 398 42 2 40 O 322 0 331 116 03 00 0 494 524195 4 391 84 APRIL 2011 Pag
8. OFFICE OF STRUCTURES MANUAL FOR HYDROLOGIC AND HYDRAULIC DESIGN CHAPTER 11 APPENDIX B TIDEROUT 2 USERS MANUAL 4 ete z l B 81529210106 D 1 J i 4 E PES r 6 A 1 2 a T 2 sf I d jei Pv 20 I MT c 72 ipn e ren Ay v 2 4 ml iu Vater im TX lt P Pd Ly a Pm we s P Version 2 Build 1 22 June 29 2006 APRIL 2011 APRIL 2011 Page 1 Preface TIDEROUT 2 Build 1 22 dated June 29 2006 is the current version of this program and all previous versions should be discarded The user 15 advised to check the web site below for revisions to the program http www gishydro umd edu The material presented this TIDEROUT 2 Users Manual has been carefully researched and evaluated It is periodically updated and improved to incorporate the results of new research and technology However no warranty expressed or implied 1s made on the contents of this program or the user s manual The distribution of this information does not constitute responsibility by the Maryland State Highway Administration or any contributors for omissions errors or possible misinterpretations that may result from the use or interpretation of the materials contained herein TIDEROUT 215 a flood routing program Its primary purpose is to serve to estimate scour at bridges in ti
9. Run Draw Tools Help Project Data Stream Flow data Tidal Basin Data Bridge Opening Data Roadway Data Output Graphic Discharge Coefficient Cd E Default value Bridge opening area rating table Input as the elevation area pairs in ascending order The first data shall be the invert Insert row Delete row BridgeiF oad Tool Discharge Coefficient Refer to F 1 Help For small bridges the default value has been selected as 0 6 For larger bridges particularly those with streamlined abutments a more reasonable value would be 0 8 Bridge Waterway Area Opening Rating Table The waterway area rating table is provided by the user as a set of elevation vs waterway area pairs See F 1 Help The waterway area for various water surface elevations can be measured from the bridge plans APRIL 2011 Page 9 ROADWAY DATA TIDEROLIT2 C X2008 old stuff on tidal hydraulics 2008 fred tidal presentation EXAMPLE 1 4 11 OB tid File Run Draw Tools Help Weir Flow Coefficient Cw 2 5 Use default value Roadway Profile Ascending Station Order Station ftm Elevation ftir 1 100 Insert Row 4 46 Insert Row 4 09 Delete Row Dele Ru 3 2 3 81 BridgefRoad Tool 4 2 25 3 23 2 0 2 62 2 35 2 95 3 2 4 3 Weir Flow Coefficient See Help Roadway Profile Ascending Station Order See F 1 Help Boundary Conditions This roadway data card represents a very important boundary c
10. dal waterways It can be used to route riverine flows from an upland watershed down to the tidal basin and then route the combined riverine tidal flow through the bridge and perhaps over the road down to the sea e Basic equation Inflow Outflow Storage e Bridge flow roadway overtopping flow tidal flow riverine flow Many newly designed OBD tidal bridges span wetlands and do not constrict tidal flow so as to cause significant contraction scour contraction scour may be more of a problem with older structures that do constrict the waterway area The advantages of the TIDEROUT program include 1 Takes into account conditions of unsteady tidal flow 2 Evaluates potential benefits of storage in the tidal basin upstream of structure 3 Provides a means of combining riverine and tidal flow hydrographs to estimate the worst case scour condition 4 The user can very quickly change input parameters to do sensitivity testing of reasonable combinations of storm tides riverine flow wind conditions etc to find the worst case Scour The limitations of the TIDEROUT 2 program include 1 Method does not address other aspects of tidal flow such as littoral drift or movement of sediment through the tidal basin 2 Method cannot be used for complex tidal currents resulting from flows between islands where wind forces predominate APRIL 2011 Page 2 3 User needs to manually compute contraction and local abutment scour 4 User needs
11. e 13 OUTPUT RESULTS SKETCHES 10 10 8 8 E E t T d aH 4 4 E E g 8 Elevation vs Bridge Opening Area 10 10 8 8 S d K 2 2 4 4 E E 1s Elevation vs Basin Surface Area APRIL 2011 Page 14 Tidal Riverine Hydrographs For this case the user selected a riverine hydrograph with a constant discharge Headwater Tailwater Relationships at Bridge Note that the velocity of flow thorough the bridge is highest When the head differential across the bridge 15 greatest APRIL 2011 Page 15 SCOUR COMPUTATIONS FOR TIDAL BRIDGES HEC RAS TIDAL COMPUTATIONS Two flow conditions should be checked for each combination of riverine and storm tide discharges to be evaluated 1 The riverine discharge with low tide elevation 2 The combination of riverine and maximum storm tide discharges at mid tide elevation Note that the maximum storm tide discharge can be estimated as Q max 3 14 VOL T Where VOL volume of water in the tidal prism between high and low tides and T tidal period selected as 24 hours for the Chesapeake Bay 3 The HEC RAS results can be used as input to ABSCOUR 9 to develop an evaluation of scour at the bridge TIDEROUT SCOUR COMPUTATIONS The clear water scour equation Refer to the ABSCOUR 9 Users Manual in Chapter 11 is used to estimate scour from the TIDEROUT 2 output tables A portion of the table depicting flow
12. een developed as a part of a project study it can be manually input here The user can also click on the generate hydrograph button to obtain a TR 20 single area model A window is presented to input the hydrograph characteristics We note that the TR 20 peak factor constant 1s 484 for all of the physiographic regions in Maryland except for the Eastern Shore which 1s 284 The time step selected in normally 0 1 to 0 2 hours to be consistent with the tidal hydrograph The user can shift the stream inflow hydrograph so that the peak riverine discharge coincides with the peak tidal flow elevation at time zero or with any other tidal flow elevation or discharge For example assume that the time of concentration of the riverine hydrograph peak occurs at time 19 hours and the user desires to shift the hydrograph so that this peak occurs at time zero for the tidal hydrograph This is accomplished in the following manner 1 compute the hydrograph and then 2 adjust the hydrograph time discharge pairs for each time unit to shift the hydrograph peak to the desired time In the example presented above the hydrograph would need to start at time 19 hours so that the peak flow would occur at time zero APRIL 2011 Page 7 TIDE BASIN DATA mum old atal om tidal Tred tidal preventatenitAAMPLe 1 4 11 tid Fie Run Drs Toots Help eject Gata Stream Flow data Tidal Basin Data Beidge Opening Data Roadway Data Output
13. et and a particle size of 0 0016 the critical velocity of the sand is estimated as 3 6 fps Solve the equation for y2 total contraction flow depth including flow depth e q Vo yo Vc y2 then APRIL 2011 Page 17 e y2 q Vc yo 6 9 3 7 7 6 14 2 ft Contraction scour depth ys y2 yo 14 2 7 6 6 6 say 7 feet Total Abutment Scour Depth y2a e y2a 1 4 y2 1 4 14 2 19 9 ft 6 Abutment scour ysa ysa y2a yo 19 9 7 6 12 feet The estimates of 7 feet of contraction scour and 12 feet of abutment scour should be evaluated in the context of the Office of Structures policies in Chapter 11 to determine the appropriate design for the bridge abutments If the bridge foundations include a pier in the waterway the above information can be input in the pier module in ABSCOUR 9 to compute the pier scour Modified Neill s Curve for Non cohesive Soils in the Piedmont Region See Chapter 11 for Cohesive Soils 1 00 am he oOo a a a E or iiii a E Ht ERN TET SIAN 1 LILL aaa ee M X ii 2 B e imb o 4 I LAELT nee ULL A41 JO D E a T a 0 0001 0 001 Critical Velocity fps o APRIL 2011 Page 18
14. me hr j 0 Analysis ending time hr j Time step ihr z Starting bridge headwater elevation ift 5 24 Tidal amplitude ift 3 13 Mean tidal elevation z ll Tidal period ihr 24 Tidal Peak Time 0 Stream flow of constant discharge Constant flow discharge 0 Upstream Tidal Basin Area rating Table Dat af Elevation ift Area Sf l 6 8 Z 551000 3 2 d 4 18000000 l 13000000 APRIL 2011 Page 11 Bridge Opening Data Discharge Coefficient Bridqe Opening Area rating Table Data Elevation ft 1 6 8 e 3 d 3 5 Boadway Data Weir Flow Coefficient For Uvertopping Flow Boadway Profile Dat aft Station ft 1 100 e 720 3 1640 d e340 5 3060 7 3783 a 4760 a Sooo 10 600g 11 6500 12 500 13 azuu l4 9400 15 9700 Area T 225 528 5858 Elevation 2 62 ZaD 2 95 4 3 sf APRIL 2011 Page 12 OUTPUT PRINTOUT PART 2 TIDEROUT COMPUTATIONS Note Remark show critical depth for critical flow with indicates fail to converge after 100 cycles Time Tide EL Basin EL Bridge Q Weir Bridge V Basin Area Flow Area RemarEkE hrs ft ft aw CS cts its sf av Sf der ft 0 00 5 240 5 240 0 00 0 00 000 139000000 0 588 0 z 5 235 5 238 94 99 0 65 0 241 13000000 0 588 n 0 40 5 223 5 231 195 32 7 88 0 554 19000000 0 555 00 0 60 5 2401 5 2248
15. ondition for evaluating tidal flow through the bridge For many Eastern Shore bridges roadway elevations will be below storm tide elevations and a large quantity of the tidal prism will flow over the road instead of through the bridge Similarly if the watershed boundaries for the tidal basin are lower than the peak storm tide elevations it may not be possible to estimate the peak tidal flows through the bridge For this condition the recommended approach 15 to input an extended roadway length at the watershed overtopping elevation This will serve to define the flows through the bridge as those flows below the elevation of the watershed divide APRIL 2011 Page 10 PROGRAM OUTPUT The output consists of two parts 1 a summary of the information input to the program by the user and 2 a time sequence of the changing hydraulic characteristic of the flow during passage of the selected tide and riverine hydrographs OUTPUT PRINTOUT PART 1 SUMMARY OF USER INPUT ee ee ee Maryland State Highway Administration m TideRoutz Program m Tidal Flow Through Contracted Bridge Opening m Yersion 2 Build 1 22 June 23 2006 Project WALLACE Creek no wind zetup 3zft span overtopping l U yr 4 l 4005 Time stamp 5 l z ll 1 02 59 PH Input Data Unit English Units Analysis starting ti
16. through the bridge vs time is excerpted below Time Tide EL Basin EL Bridge 0 Weir Q thre ft av cfs av cfs 4 00 3 675 3 5925 15594 72 1582 52 4 20 d 52l 3 794 1434 33 1943 29 4 40 3 393 3 656 1465 69 1972 59 4 60 3 232 3 512 1459 67 1973 55 4 50 3 077 3 365 1508 54 1928 10 5 00 2 320 1525 60 1633 63 5 20 2 761 3 085 1556 27 1381 97 5 40 2 600 2 952 1593 09 1158 37 5 60 2 437 2 6825 1538 35 3186 68 5 50 e zd 2 708 L635 81 572 10 6 00 2 110 2 600 1755 81 z567 25 amp z 1 946 2 494 1836 93 a4 84 6 40 1 733 2 394 1597 47 11 47 6 60 1 620 2 263 1941 85 00 6 80 1 459 2 147 1969 09 00 7 00 1 300 2 018 1980 62 00 7 20 1 143 1 881 1977 36 00 7 40 0 9385 1 7365 1959 11 00 7 60 0 837 582 1925 335 00 7 8 0 689 1 0 2 00 0 545 l 239 1805 58 00 8 20 0 405 1 045 1715 94 00 8 40 0 270 0 829 1595 84 00 2 60 0 140 0 581 1430 26 00 8 80 0 016 0 272 1173 16 9 00 1 03 0 115 682 75 00 9 20 0 16 0 00 83 44 00 9 40 0 322 0 331 116 03 00 wn CD oC rh M n Xin hk am oa 5 4 2 Bride V C 066 154 nee Z777 351 484 568 884 l45 953 455 780 083 345 558 T26 848 319 Basin Ar tet 15656296 18134795 l7555526 16952047 16331143 157263982 15155474 14600292 14065443 135735553 13119717 12673790 l221477 1 11729334
17. ults ELA RN Tidal crossing in close proximity to the bay Tide elevations control downstream tailwater elevations Tidal crossing at a considerable distance from the outlet to the bay Downstream tailwater controlled by normal depth Manning considerations emm tm t predominates 05 discharge predominates APRIL 2011 Page 3 BOUNDARY CONDITIONS FOR TIDEROUT 2 Tidal flow 1s complex especially if a combination of riverine and tidal discharges is to be used in the analysis Assumptions need to be made about the time of the occurrence of the peak tidal flow and the peak riverine flow If the upland drainage area 15 large and the time of concentration of the riverine flow 15 long it may not be reasonable to assume that the tidal flow and riverine flow peaks will coincide The TIDEROUT 2 model can be adjusted to account for the occurrence of peak tidal and riverine flows at different times In low lying tidal basins particularly on the Eastern shore the tidal basin boundary elevations may be at four feet or less while the storm tide elevations may be at six feet or more Careful analysis 1s needed to decide the proportion of the flows going through the bridge over the road and across the drainage divide to other watersheds FEMA maps which are commonly used to define peak storm tide elevations are based on the NGVD datum of 1929 while SHA current project mapping is based on NAVD datum of 1988
18. ydrograph Stream Flow Hydrograph Time hr Discharge cfsicms Insert row Delete row Generate Hydrograph dab APRIL 2011 Page 6 STREAM FLOW OPTION The User has two options with regard to stream flow data The objective is to get a conservative yet reasonable model combining tidal flow and riverine stream flow that includes the peak tidal flow and the peak riverine flow Given Hydrograph A conservative approach would be to arrange the time of a riverine hydrograph to peak at the same time as the tidal hydrograph peaks usually time zero Judgment is needed to decide whether it is reasonable to assume that the time of concentration of the riverine hydrograph will coincide with the peak tidal hydrograph Constant Discharge A second option is to convert the riverine hydrograph to a hydrograph with a constant discharge The height discharge of this rectangular hydrograph is determined by dividing the total area runoff volume under the hydrograph by the length of the hydrograph base This approach has the advantage of combining tidal and riverine flows when the relative timing of peak flows 15 problematical CONSTANT FLOW DISCHARGE If the constant discharge option is selected input the value of the computed constant flow discharge otherwise leave this field blank STREAM FLOW HYDROGRAPH If the stream flow hydrograph option is selected there are two ways of inputting the data If a hydrograph has already b
Download Pdf Manuals
Related Search