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Expect the Unexpected

26/12/2020

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ENGINEERING LESSONS: EPISODE 21 DWARKA EXPRESSWAY GIRDER COLLAPSED

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EPISODE 21: REPORT ON DWARKA EXPRESSWAY GIRDER COLLAPSED  Dwarka Expressway way, Package 3 bridge collapse 28/03/2021 Contractor: LNT,   Engineer: AECOM, CEG Video:  https://www.youtube.com/watch?v=mKB4fr15IEI As per VK Raina Report: Inspection of the Collapsed Spans of decks of Dwarka Gurgaon Bridge one almost fully prestressed and the other ready on hooks about to be prestressed.  Its observed that the Concrete surface at the bottoms of 2 segments was  of very  poor quality and fully honey combed, which got progressively Crushed in a matter of a  minutes. The soffit commenced crushing, progressively reducing the effective compression  section  area that in turn commenced  folding (upwards) , cracking open the top of top slab in Flexural Tension and the speeding and continuous reduction of effective section progressively Crushed the soffit,  this 1st Plastic Hinge would  Rotate fast enough not allowing the 2nd distr...
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ENGINEERING LESSONS: EPISODE 22 - OPTIMIZED LIVE LOADED VIADUCT BRIDGES

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  OPTIMIZED LIVE LOADED VIADUCT BRIDGES In the Present state of the art, a Bridge Engineer usually optimize the design component in four ways. This article will discuss about the possibility to optimize the design loads with  Effective Live Load Concept. Problem Statement: Criteria 1: The vehicle volume in the road is majorly classified into two types namely passenger vehicle segment & commercial vehicle segment. Around 90% of vehicles on road are passenger vehicle segment and only 10% of the vehicle is under commercial vehicle segment. Commercial vehicles are higher weight compared to passenger vehicles. But a Bridge Engineer is pulled to compulsion in designing the bridge for the governing vehicle load that is a commercial vehicle, even though their volume is less compared to a passenger vehicle. As per Indian scenario, IRC Class AA & A are far higher than the normal vehicles. Criteria 2: In a densely populated city there will be always an alternative route to r...
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ENGINEERING LESSONS: EPISODE 21 - INNOVATIVE IDEA TO REDUCE THE METRO VIADUCT HEIGHT

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Innovative Idea to reduce the Metro Viaduct Height Usual metro rail viaduct’s deck width will be in the range of 8.8 to 10.5m, which can be easily accommodated within the 1st lane of underneath traffic. If the 1st lane on both side of the underneath traffic is restricted with height constrains for vehicular traffic (say 3.0m), then the vertical profile can be lowered. The vehicle's with height greater than the restricted height can use the other lanes. This will ultimately help in saving the pier quantity w.r.t to concrete & steel. This will also help in reduction of design forces for the substructure and foundations; since the height of pier is reduced. Constraints in implementing the Idea In cities where the alignment has to cross much road intersection, this ideology will not provide sufficient head room clearance. Because in such case the vertical profile need to be lower/rise; but the allowable gradien...
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