- December 12, 2018Winner: Matthew McLean, University of New BrunswickShow QuestionQuestion:One mode of failure in stay cables is fatigue fracture caused by many cycles of axial stress. Four manufactures, anonymously named A, B, C, D, each submit 200 random samples of strand for fatigue testing. Each sample is subjected a stress range of 213MPa with a maximum stress of 837MPa and the number of cycles to fracture is recorded as the fatigue life, N. The large volume of data allows the creation of probability density curves for the fatigure life; these are plotted in fig 1. Which manufacture's strand would give the shortest mean fatigue life for a complete stay cable?Correct Answer:dDIncorrect Answers:aAbBcC
- November 30, 2018Winner: Jacek Doniec, WSPShow QuestionQuestion:One mode of failure in stay cables is fatigue fracture caused by many cycles of axial stress. Many samples of strand, 3.5m in length, are tested for fatigue with a constant amplitude stress range and the number of cycles to fracture, the fatigue life N, is found to have a mean of 2.5 million (fig 1). The same strand is used in stay cable specimens, each with 31 strands 3.5m in length, which are tested to the same amplitude stress range until 5% of the strands fracture. In both tests identical anchorages are used (fig 2). Which statement best describes the mean fatigue life of the stay cable specimens:Correct Answer:aless than 2.5 million cyclesIncorrect Answers:bequal to 2.5 million cyclescgreater than 2.5 million cyclesdunknown; it depends on the details of the system
- November 16, 2018Winner: Doug Griffin, Green Stream ConsultingShow QuestionQuestion:For the concrete cantilever beam shown below, what is the expected force in the bottom mat of longitudinal reinforcement given that the beam is not prestressed?Correct Answer:aAIncorrect Answers:bBcCdD
- November 2, 2018Winner: Derek Cell Smith, University of VictoriaShow QuestionQuestion:For a pull-out test on a length of standard rebar that exceeds the rebar's yield strength, which of the following pull-out load versus embedment length relations is most probable?Correct Answer:aAIncorrect Answers:bBcCdD
- October 19, 2018Winner: Matt McLean, TrimbleShow QuestionQuestion:The small prestressed concrete girder bridge shown in the figure is undergoing rehabilitation work and one of the remedial measures is the placement of a new unreinforced concrete overlay over the existing superstructure. What cracking pattern, shown in plan view below, is most likely to be observed during the lifetime of the new overlay?Correct Answer:aAIncorrect Answers:bBcCdD
- October 5, 2018Winner: Matthew Mendes, WSPShow QuestionQuestion:The average shear stress distribution over the height of a rectangular concrete edge girder loaded under positive bending to its ultimate limit state is most closely represented by which of the following diagrams?Correct Answer:cCIncorrect Answers:aAbBdD
- September 21, 2018Winner: Chaudary Murtaza, GeoMetrixShow QuestionQuestion:The bending moments in multi-span cable-stayed bridge towers are significantly influenced by the configuration of the girder and pylons at the piers. Which of the below configurations will likely result in the lowest bending moments in the towers of the Veer Kunwar Singh Bridge, shown in the figure?Correct Answer:aAIncorrect Answers:bBcCdD
- September 7, 2018Winner: Christian Orozco, Mohawk CollegeShow QuestionQuestion:Cable arrangements with 'windows' near the towers are sometimes used for cable-stayed bridges, as shown in the figure. Which of the below girder/tower configurations would be most suitable for a cable arrangement with a window near the tower?Correct Answer:aAIncorrect Answers:bBcCdD
- August 24, 2018Winner: Brandon Sparling, StudentShow QuestionQuestion:Extending ballast or large edge girders over the anchor pier and into the side span of a cable-stay bridge provides the following benefits, EXCEPT which one?Correct Answer:dSimplifies the back-stay deck anchorages.Incorrect Answers:aReduces large bending moments at the face of the anchor pier.bReduces large longitudinal angle breaks in the bridge profile over the anchor pier.cReduces the uplift forces on the anchor pier.
- August 10, 2018Winner: Sam Phan, ParsonsShow QuestionQuestion:When stiffening cables are employed for long-span cable-stayed bridges, what is their primary purpose?Correct Answer:bImprove the stiffness of the cables.Incorrect Answers:aImprove the strength of the cables.cImprove the aesthetics of the cables.dDecrease the wind-induced vibrations of the cables.
- July 27, 2018Winner: Gary Fenton, PCLShow QuestionQuestion:The longitudinal profile of tendons in prestressed concrete girders is often harped or occasionally draped, as shown in the figure. What is the primary purpose of having the tendon elevation raise near the supports?Correct Answer:dTo prevent excessive tensile concrete stresses near the top face at the support.Incorrect Answers:aTo prevent excessive tensile concrete stresses near the bottom face at midspan.bTo prevent excessive compressive concrete stresses near the top face at midspan.cTo prevent excessive compressive concrete stresses near the bottom face at the support.
- July 13, 2018Winner: Randles Needham, Acrow BridgeShow QuestionQuestion:Parallel strand cables are composed of numerous strands that are defended from corrosion by different protective layers as shown in the figure. For a typical parallel strand cable, how many protective layers are employed?Correct Answer:c4Incorrect Answers:a2b3d5
- June 29, 2018Winner: Vincent Wang, APOC Engineering Ltd.Show QuestionQuestion:Various improvements can be implemented to improve the stress-strain response of seven-wire strand tendons, which are used for both stay cables and internal prestressing. Based on the figure, what labelling order correctly lists the stress-strain curves for stress-relieved, low-relaxation, untreated, and mild steel tendons?Correct Answer:bii, i, iii, ivIncorrect Answers:ai, ii, iii, ivciii, iv, i, iidiv, i, ii, iii
- June 8, 2018Winner: Jacek Doniec, WSPShow QuestionQuestion:Pier blades, such as the one shown in the figure, are often employed for part of the substructure in long continuous bridge units. Spreading the pier blades further apart gives what advantage to the structure?Correct Answer:cIncreased fixity for unbalanced cantilever rotation about the bridge's transverse axis during construction.Incorrect Answers:aA decrease in the size of the supporting foundation below the pier blades.bIncreased fixity for seismic rotation demands about the bridge's longitudinal axis in its permanent condition.dDecreased fixity for shear displacements along the bridge's longitudinal axis in its permanent condition.
- May 25, 2018Winner: Frank Maximchuk, GeoNorth Engineering Ltd.Show QuestionQuestion:Self-anchored suspension bridges are suited best for which of the below applications?Correct Answer:bPoor soil conditions at both cable-anchor points.Incorrect Answers:aPoor soil conditions at one cable-anchor point and good soil conditions at the other cable-anchor point.cWhere the girder/deck must be slender for navigational channel requirements.dWhere temporary falsework is not practical due to adverse weather/water currents.
- May 11, 2018Winner: Stanley ChanShow QuestionQuestion:Which girder/deck cross-section would be expected to exhibit the most favourable aerodynamic behaviour for very-long span bridges?Correct Answer:bBIncorrect Answers:aAcCdD
- April 27, 2018Winner: Gregory Leonard, Pennsylvania Department of TransportationShow QuestionQuestion:To help reduce bending stresses in the towers of the Base Case cable-stayed bridge below, which of the following solutions is likely to be least effective:Correct Answer:bBIncorrect Answers:aAcCdD
- April 13, 2018Winner: Rajesh Kumar, BridgeconShow QuestionQuestion:Multi-span cable-stayed bridges are becoming increasingly popular. These bridges lack the back-stay support available to typical 2- and 3-span cable-stayed bridges. As a result, they can be susceptible to excessive deflections, bending moments, and stress variations. To alleviate these issues, which of the following alternatives has been implemented most frequently:Correct Answer:aAIncorrect Answers:bBcCdD
- March 16, 2018Winner: Francois Leprince, CIMA+Show QuestionQuestion:Which of the cable-stayed bridge towers below will likely experience the highest stresses due to live loads?Correct Answer:aAIncorrect Answers:bBcCdD
- March 2, 2018Winner: Aman SidhuShow QuestionQuestion:Ship collision is important for bridges situated on major waterways carrying large ships or barges. To protect the bridge piers, engineers can place the piers on shore, use artificial islands/dolphins and other guide structures, or simply make the piers strong enough to withstand a direct collision. To design these latter countermeasures, the engineers need to consider a variety of ships that may be producing the impact forces. Which of the relationships below most closely approximates the relationship between ship deadweight tonnage (traveling at a given velocity) and impact force?Correct Answer:dDIncorrect Answers:aAbBcC
- February 16, 2018Winner: Alex Rutwind, UVic.Show QuestionQuestion:For cable-stayed bridges, heavy concrete side spans can help counterbalance comparatively long main spans. Which of the bridges below does not employ this technique?Correct Answer:dThe St. Nazaire Bridge, FranceIncorrect Answers:aThe Atal Bridge, IndiabThe Normandy Bridge, FrancecThe Flehe Bridge, Germany
- February 2, 2018Winner: Balamurali Prabhakaran, VSL India.Show QuestionQuestion:During the construction of the Basohli Bridge the stay cables were installed strand by strand. Because this operation causes the bridge to deform, each strand is installed to a unique target force. When successfully completed all strands have equal forces. Graphs A to D show sequences of target forces for a 17-strand cable, with strand 1 installed first. Which graph shows the correct sequence of target forces?Correct Answer:dDIncorrect Answers:aAbBcC
- January 19, 2018Winner: Jun Lau, UBC.Show QuestionQuestion:When investigating flutter for long-span cable-supported steel bridges, what damping ratio for the structure is most appropriate?Correct Answer:`Incorrect Answers:a0%b0.5%c2%d5%
- January 5, 2018Winner: John Mathens, Ramboll.Show QuestionQuestion:Typically, for long-spanbridges, the mass of a tuned mass damper (TMD) should be in the vicinity of __ % of the oscillating mass.Correct Answer:b5%Incorrect Answers:a1%c20%d30%
- December 15, 2017Winner: Monica Rotterdam, U of A Student.Show QuestionQuestion:Considering both the maximum fatigue stress and minimum effective stiffness of the back-stay cables of a 3-span cable-stayed bridge, which of the following bridge types will likely have the lowest ratio of side span length to main span length?Correct Answer:cSteel railway bridgeIncorrect Answers:aSteel road bridgebConcrete road bridgedConcrete railway bridge
- December 1, 2017Winner: Liza Richardson, Student.Show QuestionQuestion:What damping ratio is most appropriate when considering an 80-year old steel suspension bridge undergoing a 1-in-475 year seismic event?Correct Answer:a0.5%Incorrect Answers:b2%c5%d7%
- November 17, 2017Winner: Tanush Sharma, Freyssinet.Show QuestionQuestion:Suspension bridges are commonly fitted with a central clamp between the deck and the main cable to reduce longitudinal translation of the cable under asymmetrical traffic loads. Which of the following connections is most efficient in achieving this objective?Correct Answer:ddIncorrect Answers:aabbcc
- October 19, 2017Winner: Monique Levesque, McGill StudentShow QuestionQuestion:What is the primary reason most suspension bridges have an offset (Δ in the figure) between the cable and the deck at midspan?Correct Answer:aAesthetic considerationsIncorrect Answers:bGreater structural efficiency under dead loadcGreater structural efficiency under live loaddImproved aerodynamic performance
- October 6, 2017Winner: Stephen Novac, BCIT StudentShow QuestionQuestion:The Pont des Pierres or "Bridge of Stones," which stood in the French Alps from 1910 to 1944, had a masonry arch spanning 80m. It was constructed on wooden falsework rising out of the river bed. When both halves of the arch were complete, the key stone or "voussoir" was placed at the crown to complete the arch.
Imagine that in spring, immediately after placing the voussoir, the workers leave the site due to a payment dispute. In high summer, they return to the site to find a horizontal crack in the voussoir along a hidden flaw in the stone. The master mason wants to break out the voussoir and replace it but is concerned about collapse should there be a sudden jolt as the locked in forces are relieved. Which measure would not be helpful in reducing this risk?Correct Answer:alighting fires along the top of the archIncorrect Answers:bsoaking the wooden falseworkcwaiting until winterddriving wedges into each joint in the wooden falsework
- September 22, 2017Winner: Rachael Winchester, UVIC.Show QuestionQuestion:A three-span module of the Sultanganj Bridge is constructed by balanced cantilevering with a portion of the end spans constructed on falsework during the dry season.
After closure and removal of the falsework, the stay cables are re-stressed to improve the distribution of stresses in the superstructure.
Stay cable 14S7, 160m in length, is re-stressed at both anchorages simultaneously. Which statement about the stresses caused at points a, b, c & d in the superstructure is true?Correct Answer:ba, b are in compression; c, d are in tensionIncorrect Answers:aa, b, d are in compression; c is in tensionca, b, d are in tension; c is in compressionda, b, c are in tension, d is in compression
- September 7, 2017Winner: Terry Styran, Crown CastleShow QuestionQuestion:On the Arrah-Chapra bridge, all balanced cantilevers are complete and the final segment needs to be cast-in-place over the pier. Over a 24-hour duration, the cantilevers move vertically through a range of 60mm due to thermal effects. To the fresh concrete in the final segment, this movement would be extremely damaging. To prevent the movement, the contractor"s superintendent builds a falsework support on the edge of the well foundation which can resist vertical compression. At what time of day should the contractor engage the support?Correct Answer:csunriseIncorrect Answers:asunsetbmidnightdmidday
- August 25, 2017Winner: Mithun Mohan, International Bridge TechnologiesShow QuestionQuestion:Extradosed and cable-stayed bridges with a single plane of parallel strand cables often utilize a cable saddle in their pylons. Generally, for which of the following is not an advantage of this system compared to traditional pylon anchorages for extradosed or cable-stayed bridges that utilize a single plane of parallel strand cables?Correct Answer:bSimpler cable installation processIncorrect Answers:aNarrower pylon dimensionscSmaller overall deck widthdLess overall anchorage material
- August 10, 2017Winner: Lucas Wise, IBTShow QuestionQuestion:A suspension bridge is to be designed for a blast loading of 10kPa applied to the towers and superstructure. If this load were applied as an equivalent static force, it would govern the design of the towers, therefore a dynamic analysis is carried out to determine the influence of the short load duration.
If a load is applied suddenly and sustained for a long duration, the dynamic response of the structure will exceed the response to the same load applied statically (dynamic amplification), but if the load duration is very short, the dynamic response will be less.
If the tower has a transverse natural period of vibration of Tn = 0.60 seconds, and the loading is applied as a rectangular pulse load, what pulse load duration would produce a dynamic response equal to the response of this same load applied statically? Assume structural damping is negligible and can be ignored.?Correct Answer:atd = 0.10 secondsIncorrect Answers:btd = 0.15 secondsctd = 0.30 secondsdtd = 0.60 secondsetd = 1.20 seconds
- July 28, 2017Winner: Wolfgang Konn from Arcadis ConsultantsShow QuestionQuestion:Which of these stiffening girders are most suitable for a cable-stayed bridge with a single cable plane?Correct Answer:cCIncorrect Answers:aAbBdD
- July 14, 2017Winner: Steve Fung, Schnabel EngineeringShow QuestionQuestion:Which of these pylon configurations is most favorable in terms of aerodynamic stability?Correct Answer:aAIncorrect Answers:bBcCdD
- June 30, 2017Winner: Anna Lemaire, COWI NAShow QuestionQuestion:The low inherent damping of stay cables may require countermeasures to reduce the potential for unstable oscillations. One of these countermeasures is the use of helical fillets that are incorporated on the outside of the stay cable HDPE protective pipes. The primary purpose of the helical fillets is to prevent what type of dynamic excitation?Correct Answer:bWind-rain galloping oscillationIncorrect Answers:aIce galloping oscillationcWind buffetingdWind vortex shedding
- June 16, 2017Winner: Jacob Kern from FlatironShow QuestionsQuestion:For suspension bridges, what is typically the most economic type of pylon cross-section?Correct Answer:aHollow concrete section, e.g. on the Lillebaelt BridgeIncorrect Answers:bSteel multi-cellular section, e.g. on the Golden Gate BridgecSteel box section, e.g. on the Lelu Island BridgedSteel mono-cellular section, e.g. on the First Bosporus BridgeQuestion:Generally speaking, when does this system produce an overall less economical bridge design?Correct Answer:cIn locations with very poor soil conditionsIncorrect Answers:aIn areas with high air trafficbIn regions with high seismic hazarddIn regions with high design wind speeds
- June 1, 2017Winner: Brian Taylor, BC Ministry of Transportation and InfrastructureShow QuestionsQuestion:Generally, what cable arrangement theoretically requires the least amount of cable steel for cable-stayed bridges with spans between 200m and 300m?Correct Answer:bFan, e.g. the Pasco-Kennewick BridgeIncorrect Answers:aSuspension, e.g. the Lelu Island BridgecHarp, e.g. the Arrah-Chhapra BridgedFan-Harp, e.g. the Nipigon River BridgeQuestion:What is the main reason this system is not commonly used?Correct Answer:aRequires expensive anchoragesIncorrect Answers:bLong construction durationcLess aesthetically pleasingdRequires specialized construction equipment
- May 19, 2017Winner: Jose C Calisto da Silva, STV Inc.Show QuestionsQuestion:Over the past 10 years, what is the most common type of stay cable system?Correct Answer:dParallel strand cable, e.g. used on the Atal Setu BridgeIncorrect Answers:aFiber strand cable, e.g. used on the Storchenbrücke BridgebLocked-coil cable, e.g. used on the Deh Cho BridgecParallel wire cable, e.g. used on the Helgeland BridgeQuestion:What is the main advantage of this system?Correct Answer:cHighest tensile strengthIncorrect Answers:aMost durablebHighest stiffnessdLeast creep