Introducing 

Prezi AI.

Your new presentation assistant.

Refine, enhance, and tailor your content, source relevant images, and edit visuals quicker than ever before.

Loading content…
Loading…
Transcript

ANALYSIS

UNDERLYING ISSUES

PROXIMATE CAUSE

i. Poor design

Calculating the gusset plate shear stress on the horizontal section consist:-

-The stresses on two critical sections in each gusset plate (horizontal section near the center and one vertical section adjacent to the vertical member of the node).

Demand to capacity (D/C) ratio shows the expected performance of the gusset plates.

.- A D/C ratio that slightly greater than 1 indicates demand exceeds design capacity and sometime acceptable based on professional judgment of an engineer.

- A D/C ratio significantly greater than 1 shows a design error.

D/C ratio of the gusset plates along the truss

- The gusset plates at the U4, U10, and L11 nodes had D/C ratios (for shear that exceeded 2)

- The gusset plates at two nodes had D/C slightly over for 1 shear.

- Gusset plates at the U4, U10, and L11 nodes were only half of thick as necessary to meet the design requirements.

D/C ratio of the gusset plates along the truss

- The gusset plates at the U4, U10, and L11 nodes had D/C ratios (for shear that exceeded 2)

- The gusset plates at two nodes had D/C slightly over for 1 shear.

- Gusset plates at the U4, U10, and L11 nodes were only half of thick as necessary to meet the design requirements.

ii. Extraordinary weight

- Renovations occurred that decreased the strength of the bridge and added extra weight.

- Dead load = increased due to repair and maintenance

- Live loads increase due to traffic demand. The four of the eight lanes were closed for resurfacing during an accident

Main cause of this problem:-

-Undersizing of gusset plates that connecting members of the bridge.

- The loss of structural support from the bending and fracturing of the gusset plates (U10 and L11)

- Increased weight caused by reconstruction

iii. Failure inspections involved

Sequence of failure inspection: 1990 until 2006

1990 - The federal government gave I-35W bridge a rating of ‘structural deficient’.

7 years later - University of Minnesota Civil engineering department - Out of plane-distortion in the main trusses due to resistance to motion at the connection cross bearings.

Action taken: the cracks in the girders were drilled to prevent further propagation. Support struts also added to cross girder.

2001-2005 – Fatigue cracks in the bridge’s trusses, and the bridge has no secondary system to bear the weight of traffic.

2005 - According to U.S Department of Transportation’s National Bridge Inventory database-The Bridge was again rated as ‘structural deficient’ and in need of replacement

.

2006- Several instances of poor weld details, section loss, pitting, flaking and corrosion were determined.

2007- I-35W Bridge collapse on August 1.

Corrosion of members and bearings of the I-35W bridge

CASE STUDY BACKGROUND

ANALYSIS OF ETHICAL ELAPSE

1. Duty Ethics.

2. Utilitarianism

Duty ethics

-Engineers have a duty to ensure the safest result possible.

-Based on code of conduct 1.0: A registered Engineer shall at all times hold paramount the safety, health and welfare of the public.

-No one organization or engineer or involved parties wants to take the blame instead of ignore about the safety of the bridge.

Utilitarianism

- A maximum benefit should be delivered to a maximum number of people.

- Decision making to reconstruct the bridge should be analyzed either the action taken effect a large amount of people or not since it is a public road.

1. Interstate 35W Mississippi River Bridge in Minneapolis (I-35W) were based on 13 reinforced concrete piers and 14 spans, number as Figure 1.4.

2. The south approach spans were supported by south abutment; by piers 1, 2, 3 and 4; and by the south end of the deck truss portion.

3. Meanwhile, the north approach spans were supported by the north abutment; by piers 9,10,11,12 and 13; and by the north end of the deck truss portion.

4. The 1,064 ft. deck truss potion of the bridge consists of a portion of span 5; all of spans 6, 7 and 8 and a portion of span 9.

5. The deck truss was supported by four piers; piers 5, 6, 7 and 8.

1. 1971, Minnesota Department of Transportation (MN/DOT) conclude the bridge will be continued to be inspected by annually.

2. 1990 years later, federal government inspect the bridge and they gave the I-35W Bridge a rating of “structurally deficient”, citing significant corrosion in its bearing.

3. 2001, Civil Engineering department of the University of Minnesota detect cracking, distortion and lack of redundancy at the bridge.

4. 2003, the National Bridge Inventory give a general report based on the inspection of the bridge and at the same year, Civil Engineering Department of University of Minnesota claim that the bridge is considered to be a non-redundant structure.

5. 2005, The bridge was again rated as “structurally deficient” and need possible replacement by the US Department of Transportation’s Nation and National Bridge Inventory in year 2005.

6. 2006 month later, the US Department of Transportation’s Nation found problems of cracking and fatigue on the bridge.

7. 2007, The bridge continuously inspects by annually but no inspection report was completed.

1. The possible cause of the collapse was the insufficient capacity of the U10 gusset plates.

2. An error by the original bridge design firm and the firm failed to counter all necessary calculations when designing the main truss gusset plates.

3. Combination of loads from original bridge weight, additional weight by renovation of bridge, traffic load, and constructions material and vehicle contribute to the catastrophic where those contributors are placed at the area concentrated above U10 nodes (U10 gusset plates).

4. The bridge design shows that the U10 and L11 gusset plates were only half thick as necessary.

5. It has been confirmed in the finite element analysis that the insufficient of U10 and

INTRODUCTION

1. On August 1, 2007, 6.05 p.m., the Interstate 35W Mississippi River Bridge in Minneapolis (I-35W) collapsed into the river and its banks.

2. The 40 years old bridge collapsed without warning on the peak hour involving hundreds of vehicle fall into the river and causing the death of 13 people and 145 injuries.

3. Originally the bridge consisting of 8 lanes with the size of 1,907ft long and 115 ft. high and it was connected the downtown neighbourhoods of Minneapolis aside the Mississippi River.

THE END

4. The north end of the bridge was located near hydroelectric plant while the south end was located near a coal to gas processing plant.

5. The bridge was under construction where two outside lanes northbound and two inside lanes southbound were closed to the traffic.

6. All equipment and aggregates were ready and the work will be begun by 7pm.

7. The construction is for concrete pour at the southbound lanes that were positioned toward the south end of the centre section of the deck truss portion of the bridge.

CONCLUSION

The main reason for the bridge to collapsed are by the structure deficient. Besides, the inedequate rigorous inspections and insufficient responsibilities among parties involved were contribute to this bridge failure.

Ethical behavior is defined as “a set of moral principles, rules, or standards governing a person or profession. Major principles of ethical conduct include that the development should do no harm, that privacy and anonymity of users must be protected.

Technology played a major role in managing the response and recovery efforts. From the real-time awareness provided by site video cameras, to the Web-based Geographic Information System (GIS) Common Operating Picture and traffic management systems, to the use of municipal Wi-Fi, technology was tried and tested in the I-35W Bridge Incident. The technology not only performed well, it transformed the way response and recovery were handled [6].

I-35W Mississippi River Bridge

Learn more about creating dynamic, engaging presentations with Prezi