Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure. Advanced bridge hydraulics with hec ras awi122110 an overview of unsteady flow simulations using hec ras awi031511 bridge scour computations with hec ras awi1104102 hec ras bridge hydraulics awi101410 understanding hec ras errors, warnings, and notes awi100510 understanding the use of ineffective flow areas in hec ras awi021411. Hecras is an integrated system of software, designed for interactive use in a multitasking, multiuser network environment. These methods are not meant to be used to do any kind of detailed bridge design or bridge scour analysis contraction, abutment, or pier scour. Army corps of engineers hydraulic engineering center river analysis system hecras software program. Hec6 scour and deposition in rivers and reservoirs, users manual, davis. Scour is a function of pier geometry and the vortices that form around piers, moreso than the shape of the pile cap or pier foundation. Request for bridge scour analysis for complex pier. There is no need to rerun the hecras simulation in order to access already computed results.
Technical supplement 14b scour calculations ts14bii 210vineh, august 2007 tables table ts14b1 examples of bridge failures associated with ts14b2 scour table ts14b2 streambed erosion and deposition processes ts14b3 table ts14b3 types of scour analyses ts14b5 table ts14b4 constants for computation of minimum armor. Riskbased approach for bridge scour prediction final report prepared for. Hecras river analysis system is bridge scour prediction software developed by the army corps of. Hecras does not compute longterm aggradation or degradation. Hydraulic design of highway culverts, third edition. Hydrologic engineering center river analysis system hec. Jul 31, 2017 learn how to model bridges using hec ras. Obtain bridge opening data including abutment and pier data.
Bridge hydraulic analysis with hecrasi vernon bonner and gary brunner hydrologic engineering center, us army corps of engineers introduction the hydrologic engineering center hec is developing next generation software for onedimensional river hydraulics. Tip never use the default output of a hydraulic program unless. It however was found either significantly overpredict or underpredict scour compared with actual field observation. This document is available to the public through the national. Bridge scour definition, causes, calculation of scour depth. Hecras evaluates the worstcase scour considering erodible material. Our findings are based on the updated hecras model as discussed below. There are two companion documents, hec20 entitled stream stability at highway structures, and hec23 entitled bridge scour and stream instability countermeasures. Example 11, bridge scour, presents the determination of a bridge scour. Bridge design scour analysis channel stabilization pump stations small. It predicts scour at bridge crossing reasonably well for simple regular channel. The scour computations in the hecras software allow the user to compute contraction scour and local scour at piers and abutments. Hecras river analysis system users manual version 4. Army corps of engineers hydrologic engineering center s hecras software program is a widely used tool for various openchannel hydraulics analysis and design tasks.
National cooperative highway research program transportation research board national research council washington, d. Nchrp project 2005 monitoring scour critical bridges project 24072 countermeasures to protect bridge piers from scour project 24152 abutment scour in cohesive materials project 2420 prediction of scour at bridge abutments project 2426 effects of debris on bridge pier scour project 2429 scour at bridge foundations on rock. Computing scour with hecras assuming your bridge design or analysis is already complete a. The system is comprised of a graphical user interface gui, separate hydraulic analysis components, data storage and management capabilities, graphical and tabular output, and reporting facilities. For information on the bridge scour equations, please see chapter 10 of the. Bridge hydraulic analysis with hecras hydrologic engineering. A common analysis task when preparing new bridge designs is to estimate the potential for scour at the bridge crossing. During the computations the user must request detailed flow distribution output at the cross section just upstream of the bridge and at the approach section. This is particularly important when computing potential bridge pier scour. Advanced hecras features 11 computing scour at bridges the computation of scour at bridges within hecras is based upon the methods outlined in hydraulic engineering circular no. Bridge scour calculations in hecras using methodology. The software will automatically load results from previous model runs, including imported hecras models.
Hydraulic analysis bridge scour analysis will be based upon four selected events. Water may flow through multiple paths and directions at the bridge opening. These results help determine how long a bridge needs to be, how high the bridge deck should be designed to provide adequate flood protection, and how deep to design bridge foundations to withstand scour erosion around piers. Before performing a scour analysis with the hec ras software, the engineer. Advanced bridge hydraulics with hecras awi122110 an overview of unsteady flow simulations using hecras awi031511 bridge scour computations with hecras awi1104102 hecras bridge hydraulics awi101410 understanding hecras errors, warnings, and notes awi100510 understanding the use of ineffective flow areas in hecras awi021411.
Chapter 12 computing scour at bridges c h a p t e r 12 computing scour at bridges the computation of scour at bridges within hec ras is based upon the methods outlined in hydraulic engineering circular no. The system is comprised of a graphical user interface gui, separate hydraulic analysis components, data. Hecras applications guide hydrologic engineering center army. In addition, the results of the scour analysis are to be used to determine the bridge inspection coding for item 1 scour. Help information provides descriptions of each of the more than 200 items that make up a data set for a bridge scour site. Click the box labeled downstream for a subcritical analysis.
Estimation of potential bridge scour at bridges on state routes in. Once this option is selected the program will automatically go to the output. In the united states, bridge scour is one of the three main causes of bridge failure the others being collision and overloading. The bsdms has been developed to support preparation, compilation, and analysis of bridge scour measurement data. In addition, hecras can be used to perform dambreak inundation studies, delineate floodplains, and model. Completion of a training session in stream stability and bridge scour is recommended. The current version of the hecras software does not allow 122. The hecras river analysis system is intended to be the successor to the current. Army corps of engineers river analysis system hecras is software that allows you to perform one dimensional steady and unsteady flow river hydraulics calculations. Hec ras river analysis system users manual version 4. This is a beginnerlevel webinar designed to familiarize hecras users with the scour analysis. Hecras software allows the user to select from multiple scour estimation equations in level2 scour analyses at bridges. The obtained cross sections were defined in the hecras software, and the hydraulic characteristics of the flood bed and the water surface profiles of the q 25, q 50, q 100, and q 500 flood recurring and onedimensional floodplain analysis of the tigris river were determined. Dec 30, 2015 it can account for subcritical, supercritical, and mixed flow regimes.
Start hecras and open the appropriate project and plan files for your bridge 1. Using hecras to evaluate scour at bridges county of orange presented to the flood division august, 2001 by. Tereska conducted penndots first 2d hydraulic model analysis using sms software. The bridge scour evaluation follows closely the hec18 4th edition methodology. Lagasse pi ayres associates fort collins, colorado dr. To download hecras, go to the us army corps of engineers web site. Aug 23, 2017 performing bridge hydraulic analysis to assist with bridge design. Hecras river analysis system is an integrated system of software, designed for interactive use in a multitasking environment. Scour critical bridge poa and recommendations for f17ae. All major hec2 program features and options have been incorporated in hecras, including bridge and culvert analysis, and floodway computations. Technical memorandumscour analysis for the hansen creek pedestrian bridge project the development of flood insurance rate maps firms.
Americans hydraulic modeling capabilities range from simple onedimensional modeling to complex twodimensional models. A suggested stepbystep procedure for computing scour with hecras assuming your bridge design or analysis is already complete a. One dimensional modeling is often sufficient for a bridge hydraulics evaluation and is performed with united states army corps of engineers usace hydraulic engineering centers river analysis system hecras software. Hecras is user friendly, computationally efficient, and runs within, and fully supports, the microsoft windows environment. Evaluating scour at bridges federal highway administration. It presents the state of knowledge and practice for the design, evaluation and inspection of bridges for scour. Current methods of analyzing scour depths are based mainly on laboratory experiment rather than on practical field data. Bridge scour is the removal of sediment such as sand and gravel from around bridge abutments or piers. And, there are other drawbacks to using a hec ras 1d model for bridge analysis. Hydrologic engineering center river analysis system 2. Hecras includes the ability to calculate scour depths. Users may interactively store, retrieve, update, and display bridge scour and associated data. Hec20 provides guidelines for identifying stream instability problems at stream crossings that may cause scour damage to bridges or culverts figure 2. Participants will develop their own hecras models and perform floodplain encroachment analysis, bridge and bridge scour computations, culvert analysis, and other hecras modeling work.
It is the most commonly used tool for river hydraulics in the united states. Scour analysis for the hansen creek pedestrian bridge project. She has developed and taught courses on hecras, scour analysis, hydrology and watershed modeling, and culvert design and. Scour analysis was conducted using the procedure outlined in fhwa hec18 for scour at. Bridge hydraulic analysis with hec rasi vernon bonner and gary brunner hydrologic engineering center, us army corps of engineers introduction the hydrologic engineering center hec is developing next generation software for onedimensional river hydraulics. The cherry creek channel is modeled using the watershed modeling software wms. Lsiorb east end bridge over ohio river scour analysis report kytc item no. States typically have regulations regarding how to evaluate scour and ensuring that scour protection is in place to the determined depth.
Then, the software will update the 2d mesh to incorporate the bridge piers into the mesh geometry. Omega performed all hydrology and hydraulics studies and engineering for the project, including bridge hydraulics, scour analysis, inline detention and retention mitigation, culvert layouts, storm sewer and bridge deck drainage design, an impact study for keystone dam, fema floodplain mitigation, and broken back culvert analysis. Links to software produced by others hecras, wms, and sms are also provided below. Before performing a scour analysis with the hecras software, the engineer. Hecras models steady flow using the energy equation and the standard step method, and unsteady flow using the saint venant equation. Hecras, river analysis system hydraulic reference manual. File open plan select the plan that contains the geometry file for your bridge.
This is a beginnerlevel webinar designed to familiarize hec ras users with the scour analysis features of the program. A hecras 1d model will assume that the water surface elevation is constant across the bridge opening, whereas a hecras 2d model will show that the water surface elevation varies across the bridge opening as the flow makes its way through the opening. File open plan select the plan that contains the geometry file. The methods i present in this post are strictly as a means to include a bridge in a 2d area to gage its effect on the overall resulting flood inundation. Scour by waves and currents no analytical methods available scour depth increases when even a small current is added to waves breaking waves increase scour over scour caused by currents alone inverted cone shape is similar for both cases rule of thumb estimate maximum scour depth using formula for currents alone prediction of scour. Upon completion of a scour analysis for a new bridge the scour summary sheet for known foundations is to be completed and placed into inspecttech. Hec18 is the technical standard for knowledge and practice in the design, evaluation, and inspection of bridges for scour. Hecras is an integrated system of software, designed for interactive use in a. Hecras is an integrated system of software, designed for interactive use in a multitasking, multiuser network. Quick tutorial of how to conduct a bridge scour computation within hecras. The hydrologic engineering centers river analysis system hecras is a software program used to model openchannel flow systems. It has been widely used by state dots and private design practitioners.
Hecras contains the hec18 sand contraction and pier scour equations, as. Hec ras is an integrated system of software, designed for interactive use in a multitasking, multiuser network environment. Hecras is an engineering industry standard for modeling steady. In addition, a 1d model assumes an average velocity at the bridge opening, while a 2d model will accurately represent the velocity field at the bridge.
Ntm engineerings introduction to hecras training will teach you how to use the u. Hecras software hecras with autocad, microstation, arcgis. Hecras has been used to design hydraulic structures, for bridge scour analysis, floodplain analysis, dam break and levee breach analysis, sediment transportation, evaluation of deposition in reservoirs, and. Bridge scour definition is that it is a process due to which the particles of the soil or rock around the periphery of the abutment or pier of the highway bridge spanning over a water body, gets eroded and removed over a certain depth called scour depth. In addition to the three hydraulic analysis components, the system contains several hydraulic design features that can be invoked once the basic water surface profiles are computed, including bridge scour computations, uniform flow computations, stable channel design, and sediment transport capacity. Hzu has completed the requested bridge scour analysis for complex pier foundation. Simply stated, hecras software is used to model water flowing through rivers and compute water surface profiles, including the analysis of where water will encroach in a flood event. However, it will compute local scour and contraction scour. Army corps of engineers hec ras, river channels, mixed flow regime analysis, subcritical and supercritical flow regimes, bridge and culvert analysis and design, multiple bridge and culvert openings, fhwa publication, bridge scour computations, fema, floodplain, floodway encroachment, split flow, dendritic networks. Hecras hydraulic reference manual hydrologic engineering. Automated bridge scour computations for fhwa and state dot roadway studies imports and exports standa rd hecras model files, ready for agency submittal imports standard hec2 model files. In the present analysis, hec ras was used to simulated unsteady flow in the kalyani. The software can be used to perform flood studies, analyze backwater effects at roadway crossings i.
Us army corps of engineers scour and scour protection. Procedures for performing this type of analyses are outlined in the hec no. Before using hecras for your project, you will need to collect the. Entering bridge scour data the bridge scour computations are performed by opening the hydraulic design functions window and selecting the scour at bridges function.
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