Brays Bayou Modifications & Greenbriar Bridge Redesign Julianne Crawford, Marie Gleichauf, Avi Gori, Sam Greivell, Jinal Mehta, Kasia Nikiel, Civil & Environmental Engineering, Rice University Motivation: Brays Bayou Development Proposed Bayou Modifications & Greenbriar Bridge Comparison of Bayou Modeling Results Cantilever Method 1 Method 2 1920s Channelization of original Brays Bayou Weir Elev. 42’ Clay • Modeled detention two Retaining Wall Spillway Weir Liner ways for validation 5’ 1950s Brays Bayou is lined with concrete Rip Rap Lateral Structure Backfill • Method 1: detention 61° simulated in HEC-HMS 2001 Tropical Storm Allison (500-yr) – $5 billion in damages to Houston 4’ x 4’ Outlet Detention Pond – Cross Section Weir – Side View Retaining Walls Flow Diversion • Method 2: detention Storage Area 2004 USACE and HCFCD begin Project Brays modifications simulated in HEC-RAS 100-Year Water Surface Profile Comparison 2015 Memorial Day storm (100-yr) – 1185 Houston homes flooded • Unsteady HEC-RAS 80 model and MATLAB 70 60 2016 Our proposed modifications added to Project Brays script developed to size 50 40 WSE (ft) WSE control structures 30 20 2021 Scheduled completion of Project Brays 10 0 20000 40000 60000 80000 100000 120000 140000 160000 Distance Upstream (ft) Task: Bayou Modifications & Bridge Redesign HMS Model RAS Model Memorial Day 2015 Case Study • Reduce the 100-year floodplain in the watershed by targeting two areas: Damage Cost (Brays) Damage Cost (RW) Percent Cost Reduction Meyerland and the Texas Medical Center Home 1 $149,000 $1,700 98.8% Home 2 $192,000 $3,700 98% • Redesign current Greenbriar bridge to TxDOT LRFD specifications, while Home 3 $128,000 $3,500 97.2% minimizing hydraulic impact on the channel Home 4 $33,000 $0.00 100% Home 5 $201,000 $0.00 100% Total Average Reduction 98.8% Quantified damage reductions for Meyerland homes by running the May 2015 Greenbriar Bridge storm with only Project Brays improvements and then with the retaining walls I-610 Tex as M edi cal Cent er Cost/Carbon Analysis 5 ft Retaining Walls Cost and Embodied Carbon Analysis of Modifications Item Total Cost ( $) Embodied CO (Kg/Kg CO ) Meyerland 2 2 Deck Slab 252,900 25,900 3 ft Retaining Walls Deck Rebar 93,600 9,200 29-Acre Detention Basin & Weir Bayou Modification & Bridge Impacts on 100-yr Floodplain Girders (Tx28 & Tx46) 44,900 21,100 Girder Reinforcement 130,700 13,800 T1W Guardrails 91,400 8,200 Bayou Modification Methodology Current Conditions Pedestrian Railings 28,300 - Reflects currently completed upstream and Inverted T Bents 93,600 9,000 middle-reach modifications Bent Reinforcement 2,000 25,200 HEC-HMS HEC-RAS ArcGIS Columns 12,800 1,400 Input: Rainfall Input: Flows Input: WSE Column Reinforcement 2,200 700 Output: Flows Output: WSE Output: Floodplain Arches 841,200 44,800 Construction 1,194,700 - Bridge Total 2,800,000 160,000 Project Brays Conditions Meyerland Retaining Walls 8,890,000 279,100 Theoretical floodplain after the completion of Greenbriar Retaining Walls 4,650,000 130,000 Project Brays (2021). Areas east of I-610 still Retaining Walls Total 13,540,000 409,100 flood severely Detention Pond Construction 5,120,000 - Total 20,433,500 568,400 HEC-HMS simulates overland flow HEC-RAS models water surface We took measures to reduce total cost and embodied carbon by switching resulting from various rainfall events elevations (WSE) at discrete cross from general steel to recycled steel, and by making the steel arches hollow at the sub-basin level sections using flows generated in HMS Project Brays + Our Modified Conditions Flooding in the problematic sections and in the Conclusions & Future Work Bridge Design Methodology upper Meyerland area is reduced. 453 • Deck: Designed by hand in accordance with AASHTO LRFD additional homes removed from the • Retaining walls and the detention basin provide up to 2 ft water surface floodplain reduction beyond Project Brays • Girders: Designed the reinforcement and prestressed strands (PGSuper) • The new Greenbriar Bridge increases conveyance through the channel • T-Bents & Columns: Used Viathor’s VBridge to construct a 3D FEM model Inundation (ft) & imported model into VBent to design pier reinforcement while enhancing aesthetic design and maintaining cost effectiveness • Foundations: Drilled shaft capacity based on skin friction and end bearing • Significant research still needs to be done to understand frequency storm magnitudes and the way we quantify and categorize flood risk A new 2-pier design for the Greenbriar bridge increases conveyance through the channel Acknowledgments Special thanks to: Dr. Philip Bedient, Dr. Phil De Blanc, Mr. Charles Penland, Dr. Nestor Rubiano, Dr. Andres Salazar, Thusitha Silva, Mr. Gary Zika 3D Finite Element Models Generated by Viathor’s VBridge and VBent.