Stephanie Ulman Stephanie Ulman Hyatt Assignment 9/10/12 0610 403-02 Failure of Mechanics 1

Executive Summary

In Kansas City, Missouri in 1881 the Hyatt Regency Hotel walkways collapsed. There are several reasons why the hotel walkways collapsed. One of the main reasons why the walkways collapsed was that there were two supporting rods on the 2nd and 4th floor. So these nuts were carrying twice the stress. This stress caused a deformation in the structural nut and washer on the box beam (joint). So therefore the joint could not hold twice the amount of stress. The box beam began to separate causing the walkway to collapse. Another reason is the communication between the companies G.E.C. and Havens Steel was not very good because there was all of miscommunication between them. The FBD below shows the structures of the original drawing and the modified drawing. The drawing on the right is the original drawing and the drawing on the left is the modified drawing.

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Introduction At Hyatt Regency Hotel the walkway collapsed in the year of 1981. There are several

reasons why the hotel walkway collapsed. One reason is that the communication

between the engineering and the fabricator was not very good. The engineer Jack D.

Gillum gave a sealed of approval was attached to the revised design of the design

drawings. One of the problems with the engineering drawing was that it had two

supporting rods. Therefore the nuts had twice the amount of stress on them. Another

reason why the building collapsed was because the washers and supporting nuts got

deformed. Daniel M. Duncan and Jack D. Gillum of G.C.E. where found guilty and

changed with gross negligence incompetence, misconduct and unprofessional conduct

and cannot practice their engineering services in two states.

NOTE: Research is also found in the problems First Problem: One of the reasons for the collapse of the hotel walkway was the engineering design. The fabricator changed the design. Originally the design looked in the pictures below.

Figure 1 shows the diagram of the 2D drawing. Also, this design is the original design of the walkways where suspended from the ceiling

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Figure 2 shoes a 3D picture of the original drawing. The original drawing has only one rod. These are some of the things the original design had:

Wide flange (overhang) beams that were used on either side of the walkway upon which was hung a box beam.

A clip angle welded to the top of the beam was connected to the flange beams with bolts

One end of the walkway was welded to a fixed plate while a sliding bearing supported the other end

The walkways were suspended from the ceilings by long rods.

The rod would pass through the top walkway and on down to the bottom walkway.

Under each walkway, a load-carrying nut would be used on each of the rods to carry the load of the walkway.

The original design called for the nuts to be 30 feet up the rods, the entire length of the rods had to be threaded. (Threading 30 feet rod is difficult and costly)

The load of this design for each hanger rod was to be 90 kN. The fabricator decided to change the original design to make it easier and less costly to construct. The change in the design made the walkways in the hotel to collapse.

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Figure 3 shows the 2D drawing of the changed design. This failed because there was too much weight on the nuts.

Figure 4 shows a 3D drawing of the modified design that the fabricator designed. The picture shows that two rods that are supporting a walkway. The two rods have nuts but only one of the nuts is carrying the weight of two rods.

This drawing is a 2D drawing of the design. This failed because there was too much weight on the nuts.

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The changes on this design were:

The change in the design put a double load on the connector rod.

One end of each support rod was attached to the atrium’s roof cross beams.

The second rod was attached to the box beam 4 inches from the first rod

They cut the rods in half and ran those halves from the roof to the top walkway and placed nuts

They threaded only about 6 inches of each end of each rod, a considerably easier task.

The load of this design was increased to 180 kN on the fourth floor box beam connections

The FBD below explained (FBD is on pg 12-14) The free body diagram below consists of the original design and the modified design. In the FBD shows the forces remain equal. The weight of each nut changes in the FBD. The right upper nut changes it has more stress on it than any other nut on the diagram. (because this design is the modified design) This nut has to carry the weight of two walkways. How the hotel was designed: The 2nd and 4th floor where designed with the modified design and the 3rd floor was made by the original design. The 4th and 2nd floor was suspended together by the ceiling. See diagram below.

Figure 5 shows how the walkways were attached. The 4th and 2nd floors were suspended together.

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The 3rd floor was suspended by the ceiling shown in the picture below.

Figure 6 shows the 3rd floor and how it was suspended by the ceiling. This walkway was

built with the original design.

The 4th floor was the walkway to collapse first. Since the 2nd and 4th floor where suspend together the 4th floor caused the 2nd floor walkways to collapse too. The picture below shows the 3rd walkway did not fall.

Figure 7 shows a picture of the 3rd floor walkway. The 3rd floor walkway did not collapse

only the 2nd and 4th floor collapsed.

As you can see in this

picture this is the 3rd

floor walkway. Also the

3rd floor walkway did

not collapse only the

2nd and 4th floor

collapsed.

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Figure 8 shows the 4th floor walkway and beam lying in the lobby of the hotel. (After the

walkway collapsed)

Second Problem The box beam consisted of two square channels. A square channel is shown below. These square channels were welded together.

Figure 9 shows a square channel. One of the problems with welding them together it causes a heat affected zone. The heat affected zone makes the steel more brittle. This was looked like when it was welded together.

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Figure 10 shows two squared channels that are welded together. The fabricator also made changes in the box beam design as well. These are lists of the original design and the changed design. Original box beam design:

The ends of the box beams were then drilled to receive the rods.

The box beam consisted of two 8 x 8.5 MC channels

The beams consisted of two 8-inch channel sections welded toe to toe to make up a box beam.

Each box beam of the walkway was supported by a washer and nut which was threaded onto the supporting rod

Change in the box beam design:

The bottom end went through the box beam and attached with a washer and nut

They then drilled another set of holes, which was offset 4 inches inward along the axis of the box beam, in the top walkway and hung the other halves of the rods from the top walkway.

The changed design caused the hotel walkways to collapse. These are the reasons why the walkways fell. Reasons why the hotel walkways fell:

The box beams resting on the supporting rod nuts and washers were deformed because of the stress that was exerted on them.

The box beam resting on the nuts and washers on the rods could no longer hold up the load.

The box beams (and walkways) separated from the ceiling rods.

The second and fourth floor walkways fell to the atrium first floor with the fourth floor walkway coming to rest on top of the second.

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Figure 11 shows the hanging rod, washer, threads and supporting nut. Also this picture shows the deformation of the washers.

Figure 12 shows a drawing of the cross section. This is going to fail because the structure is going to deform when it is under stress.

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Figure 13 shows an example of what the cross section of the 3rd box beam looked like. The 3rd box beam was deformed (the flanges have been bent significantly, and the weld is bowed out.

Figure 14 shows a picture of the cross section of the 4th beam. The box beam is really

deformed and there is a huge gap where the weld is supposed to be.

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Figure 15 shows another picture of the cross section of the box beam, (the modified design). This was on the 2nd and 4th floor. Therefore the box beam is another reason why it failed. The modified box beam was supporting nuts and washers were deformed because the nut was carrying twice the amount of stress it was supposed to. Therefore the box beam and rods could not handle the reaction forces on the nut (also stress). Therefore the walkways and the box beam separated and the hotel walkways fell. Third Problem In the Hyatt disaster there was communication problems between the fabricator and the engineers. The fabricators modified the design and the engineers approved the design without checking it. The fabricator had modified the design to use two hanging rods and the engineers approved the change without checking it. Also, the fabricators changed the design of the box beam too. (As stated above) The fabricator company name was Havens Steel. The engineering company was named GCE. Havens Steel modified the drawings and sent to GCE for approval. GCE

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sent the drawings back to Havens Steel. GCE said that there were miscommunications because the drawings that where prepared where preliminary sketches and interpreted by Havens Steel as finalized drawings. An engineer named Jack D. Gillum gave a sealed of approval was attached to the revised design of the design drawings. So the communication problem led to confusion about the engineering design. The communication problems between these two companies had an impact on the collapse of the walkways in the hotel. FBD

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The free body diagram shows that all the forces are equal. The forces and stresses that are on the nuts are different that the forces on the rods. In the modified drawing (the FBD above the upper nut is going to fail) because the nut is carrying twice the weight because it is carrying two different rods (walkways).

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Conclusion: In conclusion there are many causes why the Hyatt Regency Hotel walkways collapsed. One of the main causes there was twice the amount of stress on the modified designs. (These modified designs where on the 2nd and 4th floor. The box beam is another reason why it failed. The modified box beam supporting nuts and washers were deformed because the nut was carrying twice the amount of stress it was supposed to. Therefore the box beam and rods could not handle the reaction forces on the nut (also stress). Therefore the walkways and the box beam separated and the hotel walkways fell. The free body diagram shows that all the forces are equal in the rods. The nuts are not equal in the modified drawing because in the FBD above the nut has to carry twice the load. Therefore, this design failed because of all these things so engineers have to double check their work and have other people check it because thousands of lives can be in danger if they make a mistake.

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Bibliography: eFunda, Inc. 2012. http://www.efunda.com/math/areas/IndexArea.cfm Christianson, Julee. Cruz, Mike. Nolan, Katie. “Hyatt regency hotel walkways collapse” Engineering Failure. http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&sqi=2&ved=0CEYQFjAH&url=http%3A%2F%2Fstudents.seattleu.edu%2Fnolank2%2Fweb%2FHyatt%2520Regency%2520Hotel%2520Walkways%2520Collapse.ppt&ei=hUJKUJ8Z0pDRAaDAgZAD&usg=AFQjCNGKBaVimUzYjx2_Ov7k6UJXr7dsIg Hyatt regency walkway collapse http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&sqi=2&ved=0CEEQFjAG&url=http%3A%2F%2Fwww.materials.drexel.edu%2FPrograms%2Fsensors%2FLinks%2Fhyatt-regency-walkway-collapse.ppt&ei=hUJKUJ8Z0pDRAaDAgZAD&usg=AFQjCNFwbZO62vjOetAnmeTclRx25sVoMw Naum, Christopher. The Hyatt Regency Skywalk Collapse 1981. The Beginning of Urban Heavy Rescue. 17 July. 2011. http://commandsafety.com/2011/07/the-hyatt-regency-walkway-collapse-1981-the-begining-of-urban-heavy-rescue/