B05 Practical Exercise Bridge Demo

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Concorde Career Colleges, Memphis *

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12BALC

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Mechanical Engineering

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Feb 20, 2024

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Course 052-12B30-C45 (DL) - Phase 1 - COMBAT ENGINEER ALC - FY24 Test PE - B05: Employ Bridge Demolitions Practical Exercise Started 12/3/23 3:40 PM Submitted 12/3/23 3:53 PM Status Completed Attempt Score 170 out of 200 points Time Elapsed 13 minutes Instruction s Overall Scenario: Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. To employ these demolitions, you must first categorize the bridge and then determine the amount of explosives necessary to carry out this mission. As a leader in an engineer unit, it is your responsibility to supervise this demolition mission. Employ Bridge Demolitions Overview: The purpose of bridge demolition is to create gaps in bridges by attacking key bridge components. This makes gaps large enough to make repairs uneconomical and forces the enemy to construct other bridges on other sites. It is important to maintain economy of assets when employing bridge demolitions. Failure to appropriately employ bridge demolitions can cause unnecessary collateral damage and injure or kill Soldiers. Employ Bridge Demolitions Activities:  Determine the method of a bridge attack by identifying the type of bridge to be destroyed.  Employ bridge demolitions to create gaps in bridge components.  Employ knowledge of bridge demolitions by disabling fix/float bridges.  Calculate the amount of explosives required for concrete-stripping charges using the six-step problem-solving format. References:  TM 3-34.82, Explosives and Demolitions, 07 March 2016  GTA 05-10-033, Demolitions Card, 03 Jan 1994 Results Displayed Submitted Answers, Feedback, Incorrectly Answered Questions  Question 1 10 out of 10 points Activity 1 (Questions 1-5): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your first step is to identify the type of bridge to be destroyed. Determine the method of a bridge attack by identifying the type of bridge to be destroyed. Task : Which type of bridge is shown here? Selected Answer: c. Continuous Response Feedback: Correct. Nice work, SSG. This image represents a continuous bridge.  Question 2

0 out of 10 points Activity 1 (Questions 1-5): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your first step is to identify the type of bridge to be destroyed. Determine the method of a bridge attack by identifying the type of bridge to be destroyed. Task : For each statement below, determine whether it describes a continuous or simply supported bridge. o Question Selected Match Construction depth frequently increases at the piers a. Continuous Structure is composed of a span or multiple spans that are supported at each end b. Simply Supported Two lines of bearing are needed at the piers a. Continuous Flange size frequently increases over the piers b. Simply Supported Response Feedback: Incorrect. The correct answers are now displayed. It is recommended that you review the information about bridge categories to reinforce your knowledge in this area.  Question 3 10 out of 10 points Activity 1 (Questions 1-5): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your first step is to identify the type of bridge to be destroyed. Determine the method of a bridge attack by identifying the type of bridge to be destroyed. Task : Which type of bridge is shown here? Selected Answer: d. Bowstring bridge Response Feedback: Correct. Nice work, SSG. This image represents a bowstring bridge.  Question 4 10 out of 10 points Activity 1 (Questions 1-5): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your first step is to identify the type of bridge to be destroyed. Determine the method of a bridge attack by identifying the type of bridge to be destroyed. Task : Which type of continuous bridge has a midspan shear joint? Selected Answer: a. Cantilever bridge

Response Feedback: Correct. Nice work, SSG. A cantilever bridge has a midspan shear joint.  Question 5 10 out of 10 points Activity 1 (Questions 1-5): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your first step is to identify the type of bridge to be destroyed. Determine the method of a bridge attack by identifying the type of bridge to be destroyed. Task : It is easy to mistake a reinforced-concrete bridge for a masonry arch bridge because many reinforced-concrete bridges have masonry faces. Which of these two types is this bridge likely to be? Selected Answer: a. Masonry arch Response Feedback: Correct. Nice work, SSG. This appears to be a masonry arch bridge because the underside of the bridge has a masonry face. The underside of a reinforced concrete bridge with a masonry face is rarely faced.  Question 6 0 out of 10 points Activity 2 (Questions 6-10): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your next step is to create a gap in the bridge to be destroyed. Employ bridge demolitions to create gaps in bridge components. Task : For each statement below, determine the type of attack it describes. o Question Selected Match In this type of attack, a hinge forms at the bottom C. Bottom Attack In this type of attack, the angle should be 70 degrees to the horizontal to prevent jamming A. Angled Attack In this type of attack, a hinge forms at the top B. Top Attack Response Feedback: Incorrect. The correct answers are now displayed. It is recommended that you review the information about bridge attack types to reinforce your knowledge in this area.  Question 7 10 out of 10 points Activity 2 (Questions 6-10): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your next step is to create a gap in the bridge to be destroyed. Employ bridge demolitions to create gaps in bridge components.

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Task : Simply supported bridges should be attacked at or near the _____. Selected Answer: midspa n Response Feedback: Correct. Nice work, SSG. Simply supported bridges should be attacked at or near the midspan because bending moments are maximum at midspan, and the likelihood of jamming during collapse is reduced if the bridge is attacked at midspan.  Question 8 10 out of 10 points Activity 2 (Questions 6-10): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your next step is to create a gap in the bridge to be destroyed. Employ bridge demolitions to create gaps in bridge components. Task : You have been tasked with determining the attack method for demolishing a simply supported, steel beam deck bridge with bottom supports and the following measurements: L = 30 meters H = 2.5 meters E = 0.5 meters Your first step is to determine the height-to-length ratio. What is the height-to-length ratio for this bridge? H/L = _____ Selected Answer: 0.08 3 Response Feedback: Correct. Nice work, SSG. The H/L ratio for this bridge is 0.083 H / L = ratio (2.5 / 30) = 0.083  Question 9 0 out of 10 points Activity 2 (Questions 6-10): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your next step is to create a gap in the bridge to be destroyed. Employ bridge demolitions to create gaps in bridge components. Task : Given the H/L ratio of 0.083 for this bridge, what is the length of the required end clearance based the table below? H / L 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 E R / L 0.0002 0.0008 0.0020 0.0030 0.0050 0.0070 0.0100 0.0130 0.0160 0.0200 H / L 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 E R / L 0.0240 0.0290 0.0340 0.0390 0.0440 0.0500 0.0570 0.0630 0.0700 0.0770 E R /L = _____ Selected Answer: 0.016 0

Response Feedback: Incorrect. The E R /L value for this bridge is .0160 or 0.0160.  Question 10 10 out of 10 points Activity 3 (Questions 11-15): Your unit has received a mission directive to demolish fixed and floating bridges to deny the enemy forward movement. Employ knowledge of bridge demolitions by disabling fix/float bridges. Task: To destroy a standing Bailey bridge, place a _____ pound charge between the channels of the upper and the lower chords on the designated bay. Selected Answer: 1 Response Feedback: Correct. Nice work, SSG. To destroy a standing Bailey bridge, place a 1-pound charge between the channels of the upper and the lower chords on the designated bay.  Question 11 10 out of 10 points Activity 3 (Questions 11-15): Your unit has received a mission directive to demolish fixed and floating bridges to deny the enemy forward movement. Employ knowledge of bridge demolitions by disabling fix/float bridges. Task : When destructing stacked Bailey bridge, what is the first thing you should do? Selected Answer: a. destroy female lugs on the lower chord Response Feedback: Correct. Nice work, SSG. When destructing stacked Bailey bridge equipment, first destroy, remove, or distort the female lugs on the lower chord of all panels. Then destroy the remaining equipment as time and resources permit.  Question 12 10 out of 10 points Activity 3 (Questions 11-15): Your unit has received a mission directive to demolish fixed and floating bridges to deny the enemy forward movement. Employ knowledge of bridge demolitions by disabling fix/float bridges. Task : For a hasty attack of a pneumatic float bridge, the anchor cables and bridle lines are cut with [a] and the steel cables are cut with [b] . Specified Answer for: a axes Specified Answer for: b explosiv es Response Feedback: Correct. Nice work, SSG. For a hasty attack of these bridges, the anchor cables and bridle lines are cut with axes and the steel cables are cut with explosives.  Question 13 10 out of 10 points Activity 3 (Questions 11-15): Your unit has received a mission directive to demolish fixed and floating bridges to deny the enemy forward movement. Employ knowledge of bridge demolitions by disabling fix/float bridges.

Task : To destroy a pontoon bridge, place a ___ charge on the ________ end of each pontoon at water level. Selected Answer: b. ½ lb; upstream Response Feedback: Correct. Nice work, SSG. To destroy a rigid pontoon bridge, a ½ pound charge is placed on the upstream end of each pontoon at water level.  Question 14 10 out of 10 points Activity 3 (Questions 11-15): Your unit has received a mission directive to demolish fixed and floating bridges to deny the enemy forward movement. Employ knowledge of bridge demolitions by disabling fix/float bridges. Task : Destroy metal treadways on floating bridges by using the: Selected Answer: b. Steel-cutting formula Response Feedback: Correct. Nice work, SSG. You will destroy metal treadways on floating bridges by using the steel-cutting formula.  Question 15 10 out of 10 points Activity 2 (Questions 6-10): Your unit has received a mission directive to demolish a bridge to deny the enemy forward movement. Your next step is to create a gap in the bridge to be destroyed. Employ bridge demolitions to create gaps in bridge components. Task : The next step is to determine the required end clearance. What is the required end clearance for a 30-m bridge with an E R /L of 0.0160? Required end clearance = _____ meters Selected Answer: 0.4 8 Response Feedback: Correct. Nice work, SSG. The required end clearance for this bridge is 0.48 meters. E R /L * L = Required end clearance 0.0160 * 30 = 0.48 meters  Question 16 10 out of 10 points Activity 4 (Questions 16-20): Your unit has received a mission directive to demolish a concrete bridge to deny the enemy forward movement. Calculate the amount of explosives required for concrete-stripping charges using the six-step problem-solving format. Task : Your unit has received a mission to demolish a concrete slab bridge with the dimensions shown here. What is the mass of the required charge of TNT? Mass of the required charge = _____ lb(s). Selected Answer: 881.3 6

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Response Feedback: Correct. Nice work, SSG. The mass of the required charge of TNT is 881.36 lbs. P = (3.3h + 0.5) 3 * (3.3) P = 3.3 (3.3 x 1.8 + 0.5) 3 * (3.3) P = 3.3 (6.44) 3 * (3.3) P = 267.08 * 3.3 P = 881.36 lbs  Question 17 10 out of 10 points Activity 4 (Questions 16-20): Your unit has received a mission directive to demolish a concrete bridge to deny the enemy forward movement. Calculate the amount of explosives required for concrete-stripping charges using the six-step problem-solving format. Task : Once the mass of the charge required is determined, the next step is to calculate the width of the required ditch. What is the width of the required ditch for this charge? Width of the ditch = _____ meters Selected Answer: 3. 9 Response Feedback: Correct. Nice work, SSG. The width of the required ditch for this charge is 3.9m. W d = 2 h + 0.3 W d = 2*1.8 + 0.3 W d = 3.6 + 0.3 W d = 3.9 m  Question 18 10 out of 10 points Activity 4 (Questions 16-20): Your unit has received a mission directive to demolish a concrete bridge to deny the enemy forward movement. Calculate the amount of explosives required for concrete-stripping charges using the six-step problem-solving format. Task : After you’ve calculated the width of the ditch, what is the next step? Selected Answer: c. Determine the length of the span Response Feedback: Correct. Nice work, SSG. Step 3 is to determine the length of span, if the information is not given in the demolition reconnaissance record.  Question 19 10 out of 10 points Activity 4 (Questions 16-20): Your unit has received a mission directive to demolish a concrete bridge to deny the enemy forward movement. Calculate the amount of explosives required for concrete-stripping charges using the six-step problem-solving format. Task : Next, compare the required width of the ditch with the required length of span to be demolished. When performing this step, if Lc is equal to or less than the Wd: Selected Answer: a. Use one row of charges as specified by P.

Response Feedback: Correct. Nice work, SSG. If Lc is equal to or less than the Wd, use one row of charges as specified by P.  Question 20 10 out of 10 points Activity 4 (Questions 16-20): Your unit has received a mission directive to demolish a concrete bridge to deny the enemy forward movement. Calculate the amount of explosives required for concrete-stripping charges using the six-step problem-solving format. Task : When placing the concrete stripping charges, ensure that the shape of the end cross section of the charge is such that the width is between ___ and ____ times the height of the charge. Selected Answer: b. 1;3 Response Feedback: Correct. Nice work, SSG. When placing the concrete stripping charges, ensure that the shape of the end cross section of the charge is such that the width is between one and three times the height of the charge.