culvert-shelters-bad-ideas

WHY NOT PIPE CULVERT?

Popular opinion doesn’t make it right.

There is a popular school of thinking surrounding the question of round shelters vs square shelters.  There is no shortage of people and even “professionals” that will claim that a round shelter offers more strength than a square shelters. This couldn’t be further from the truth.  It’s easy to trace the origins of this pop-culture thinking back to the Roman arch style of  engineering.  At the time – this style of architecture was cutting edge and far stronger than anything else.  However; just as time has progressed bringing new ideas and technology; so in like fashion has our understanding of engineering grown.  Round is NOT stronger than everything else. The engineering science is there and supports this fact.  The best and most obvious evidence is in the buildings we pass on a daily basis.  How many round buildings have you seen? My guess is not many.  Sky scrapers are engineered much in the same way as the engineering behind the Rising S square bunker.  Just like the frame inside of high-rise buildings; the “exoskeleton” frame in Rising S bunker engineering re-distributes pressure and weight across the entire structure which essentially means no one point will ever bear the entire brunt of shifting earth.  Every cross section strengthens the next.

Additionally, the pipe culvert shelters have no load-bearing internal walls like the Rising S square design.  Every wall inside of the Rising S design is made of 10ga plate steel and is welded to the structure creating additional load bearing strength.  In contrast; all of the floor, “walls”, and furniture inside pipe shelters is made of wood, plywood or laminate materials.  These cheap solutions add no more strength and actually pose more of a threat to your safety in the event of an earthquake.

Water & Corrosion

Corrugated pipe shelters are risky and using round pipe or culvert as a bunker has many downfalls. One of the biggest is water corrosion.  The easiest way to make the case is to point out that these culverts were never intended to be lived in.  Pipe culvert is specifically engineered to shed water while acting as a canal for water to flow.  Every culvert is crimped together leaving tiny cracks where water can penetrate.  These culverts were never designed to be water tight and they will leak given enough time. (illustrated in the photos below)  Leaking leads to corrosion.  As the photos indicate – galvanization is not the end of concerns surrounding corrosion.  Aside of galvanization being more vulnerable to the elements than other corrosion protectorates; any areas of the culvert shelter that are welded subsequently lose the galvanization during the welding process.

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VIDEO OF A CORRUGATED PIPE CULVERT BEING MADE.

Notice that the culvert is crimped together.  CULVERT SHELTERS ARE NOT WATER-TIGHT!  Culvert is built to FLOW water through it NOT to shed or repel water. 

 

Strength & Durability

RESPONSES OF BURIED CORRUGATED METAL PIPES TO EARTHQUAKES By C. A. Davis and J. P. Bardet, Members, ASCE
This study describes the results of field investigations and analyses carried out on 61 corrugated metal pipes (CMP) that were shaken by the 1994 Northridge earthquake. These CMPs, which include 29 small-diameter (below 107 cm) CMPs and 32 large-diameter (above 107 cm) CMPs, are located within a 10 km2 area encompassing the Van Norman Complex in the Northern San Fernando Valley, in Los Angeles, California. During the Northridge earthquake, ground movements were extensively recorded within the study area. Twenty-eight of the small-diameter CMPs performed well while the 32 large-diameter CMPs underwent performances ranging from no damage to complete collapse. The main cause of damage to the large-diameter CMPs was found to be the large ground strains.  Pipe deformation can remain hidden for many months or even years after an earthquake, but can result in the progressive failure of pipes due to erosion, with disastrous and costly effects to supported lifelines. CMPs are commonly assumed to be resistant to strong earthquake effects (e.g., Youd and Beckman 1996) unless subjected to fault displacement and ground movement (e.g., Foundations 1973).

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All of the pipes were made of galvanized steel.  Corrosion damage was observable only in Pipe 26; therefore, corrosion was not a factor controlling the performance of the large-diameter pipes under study.
The strain-based analysis indicates that the large transient velocities recorded in the VNC damaged Pipes that permanent ground strains were not necessary for damage to occur. Combining these results, it is concluded that the main cause of damage to large-diameter CMP is large ground strain resulting from transient and/or permanent ground deformation.

 

Design and Layout Limitations

Space utilization is greatly diminished due to the fact that the floor has to be raised off of the bottom to accommodate enough flooring to walk on. The only place you actually get the full height of the culvert bunker is in the dead center of the walkway. The walls are rounded so you are losing almost half of the space you would have using a squared design. Another downfall is that everything built to go inside the bunker must be rounded since noting can fit flush against the rounded walls.  Because the galvanization is removed during welding, no supplemental strength can be gained through adding internal walls.

Pipe culvert shelters also feel like you’re inside of a submarine.  Low ceilings and steep arching walls make the shelter feel confined. (The last thing you need if you’re inside of the unit for a month or more)  Every layout of a culvert shelter is tight and constrictive when compared to the roomy feel of a square shelter.  Because of the limitations of working with culvert; additional branching rooms, storage areas…etc are not easily achievable.  Square shelters feel like home and the floor plans can accommodate any design you may want to incorporate. (multiple rooms,  multiple stories etc..)

 

CORRUGATED PIPE SHELTERS ARE RISKY: SUMMARY

  • Round pipe/culvert bunkers are coated with a poisonous chemical during galvanization
  • Round pipe/culvert bunkers cannot protect against even the smallest caliber of guns
  • Round pipe/culvert bunkers use wood interiors which are prone to fire, mold, pests and disease
  • Round pipe/culvert bunkers are welded and welding accelerates rust on galvanized metals
  • Round pipe/culvert bunkers are horrible for space utilization
  • Round pipe/culvert bunkers cost as much or more than stronger square steel bunkers
  • Round pipe/culvert bunkers are not earthquake safe
  • Round pipe/culvert bunkers can’t be customized to feel like a home with turning floor plans

 

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