West+Berlin+Congress+Hall


 * West Berlin Congress Hall Collapse (1980)** toc

Wiki Group 1 AE, 2010 : Eddie Carlos, Luong Fletcher, Dan Valentino, Landion Donovan-Green

[[image:berlincongresshall2.jpg caption="Figure 1 Berlin Congress Hall"]] **INTRODUCTION**
May 21, 1980 The down fall of the Berlin Congress Hall was due to poor structural design that failed to address corrosion prevention. Its structure demanded close attention to joinery. Each combining element called for protection that would provide sufficient coverage against corrosive events. Such however was not the case. The vertical movements of the arches created shear forces that placed stress on the tendons causing cracks in the slabs. Such stresses were amplified by the absence of sufficient protection against moisture and other precipitation agents such as: temperature changes and stress, wind, snow, vibrations,settlements, which caused the thin shell roof to crack. Over time these elements were able to affect the tensioning steel, leading to severe corrosion that ultimately lead to its collapse. A third of the concrete shell roof along with one of two supporting arches collapsed, causes for which were corroding stresses placed on the pre-stressing tendons of the structure.

**BUILDING DESCRIPTION**
Built in 1957, the West Berlin Congress Hall locally referred to as the "pregnant oyster", featured an auditorium roof defined by its inner and outer sections, atop a large rectangular base. Its early design included a hyperbolic parabolic roof that spanned 37,000-sq-ft across. Such was the astounding spectacle of the building. The Hall, partly paid by America and donated to Berlin, became a symbol of friendship between the United States and Germany. With its unique organic geometry, it presents an interesting structural system that addresses many areas of the field. The structural design involved the use of an oval beam which was to rest on the outer walls. This would serve as the auditorium roof's sole support, a system involving a tension ring and several concrete arches. Curvature was achieved by the assembly of several hollow reinforced concrete arches, situated symmetrically about the east-west axis, on which rested 24 panels. These elements were assigned the role of carrying the tensile loads resulting from the roof structure. Such loads were then converted into axial loads and distributed to two compact arch abutments. To secure the outer arch 82 tension elements were assigned to either half of the roof, each with 7 to 10 pre-stressed rods of high tensile steel. The panels joinery to the ring beam allowed for possible movement against the ring beam. The shape of the structure resembles that of an eye with its 3 inch thick curved shell.

Casualties of the East Berlin Congress Hall collapse included the death of one person and the injuring of five others. When the collapse occurred, eight panels tore form the ring beam and fell onto the roof of the foyer below. The remaining panels were left hanging from the ring beam by their tension elements. Post, collapse there were no signs of evident failure within each of the panels central span. The total failure of eight of the tension elements, and two partial failures was the cause of the collapse. (Crane, 1983)
 * THE COLLAPSE**

**CAUSES**
Due to the findings of the three engineers assigned to investigate the roof panels. They found that the roof panels were orientated directly on paper on top of the tension ring. They then concluded that the elements were able to penetrate the paper causing great corrosion, which led to a large amount of tension wire breaking( Kordina, Stuttgart, Engell). The break of the supporting tensioning elements caused the southern arches to lose equilibrium, which led to the its down fall, as the design could not adequately resist the unsymmetrical nature of the natural loads. Professor Jorg Schlaich of the University of Stuttgart's Institute for Massive Construction, says he roof joint concrete was of " insufficient, uneven quality, very porous and had, by today's standards, too-high chloride content( Schlaich)."

**ANALYSIS**
After analysis, two types of fractures were found within the beams. Type 1: showed evidence of distinct shear lips and obvious necking, indicative of ductile fracture. The fractures were matt-gray and rust free Type 2: expressed corrosion to various degrees. Necking was not visible.

All the beams that had type 1 fracture were those of the reinforced arch, with one exception. Eight of the beams that failed had type 2 fractures, and seven of them were adjacent, multiplying the weakening effect of the fracture. one element contained both types of fractures, signifying that the type 2 fracture was more directly the cause collapse, and the type 1 fracture was more a result of the collapse.

The tension elements were cut .5m on the ends for further investigation, revealing micro- and macroscopic fractures. The bottoms of the ducts showed significantly more corrosion than the tops. Upon inspection, remnants of bituminous felt were found on the undersides of several ducts, which meant that the ducts were not covered by cement. This allowed moisture to seep in and to cause the steel rods inside to become corroded. Additionally, the grout inside the duct was not evenly spaced, and was sand-rich and crumbly with high porosity, which are ideal conditions for steel corrosion. The steel rods that were pushed to the bottom of the duct, allowed for even more moisture to corrode them. The concrete and mortar in the ring beam joints were porous and permeable, creating insufficient protection against steel corrosion. The corrosion weakened the joints, lowering the amount of load that the elements could hold, therefore causing bending stresses, until finally it collapsed. (F. Buchhardt, et at., 1984)

The compilation of separate investigations of different details of the structure drew conclusions from corresponding observations and investigated the ultimate bearing capacity of the roof system and forces it would generate.

**PREVENTATIVE MEASURES**
Investigative reports detailing the causes for the hall's initial failure, influenced a decision to rebuild the hall. From such reports preventative measures were established which would govern the new design. The understanding behind live loads and its unpredictability should be taken into account. Effect of corrosion on a steel component is a reduction of its effective cross section. Such proves a serious problem when a component is of a small cross section loaded with high stresses. By paying close attention to a structures joint system and its fittings of pre-stressing tendons as well as the tendons themselves, one is able to provide effective protection against corrosion. One must also take into consideration the presence of moisture and how it affects materials inwardly and outwardly. A high amount of hydrogen atoms in contact with steel members disrupts the molecular structure of the steel, causing internal stresses. Sufficient coverage is necessary to avoid such problems caused by moisture.

The early design could not adequately resist unsymmetrical loads, such as wind and snow as prescribed by German standards. As a result, the roof was redesigned and divided into two zones; an inner and outer zone. This was not the result of the roof being the major culprit to the Hall's down fall,but rather the result from unsymmetrical loads. The roof was simply dragged along with the failing tension rings. If the roof panels did not have to endure the varying stresses, it would never have cracked, which would never have led to the corrosion.



Source detailing the collapse of the Berlin Congress Hall, providing a technical in depth synopsis to the structural failures and systematic lackings that resulted in the fall of a portion of the paneled roof. Source is divided into an Introduction, familiarizing the reader with the incident, a description of the building, presenting the faulted structural design, and several analyzing sections which break down the reasons for the buildings failure.
 * Bibliography**
 * Alan P. Crane (1983) //Corrosion of Reinforcement in concrete Construction,// Ellis Horwood Limited, England (79-89)**

Provides an analytic look to the structural materials of the Congress hall focusing on the corrosive damage suffered that lead to the structural collapse. Source summarizes the after math of the failure, revealing several major areas of corrosion that ultimately lead to the fall of the paneled roof about its ring beam.
 * Feld, J and Carper, Kenneth (1997),//Construction Failure//, 2nd Ed., John Wiley & Sons, New York, NY (320-321)**

The article stated that the Congress Hall collapse preceded by a 20 second rumbling feeling like an “earthquake.” The partially falling roof destroyed multiple of items some include: five cars, a one-story-high lobby and sets of stairs. The article then began describing the many components that made up the structure. The curved concrete ribbon was said to have snapped off and one of the support points. Stubbins says otherwise stating “the collapse of one side of the concrete shell roof could likely have thrown the rest of the roof structure off balance.”
 * "Berlin Congress hall roof falls," //Engineering News Record//. vol. 204 no. 22; (14-15)**

Professional engineers claim that the Congress Hall collapse was because the pre-stressing tendons were holding up to much. The vertical movement of the arches due to concrete creep, temperature stress, and many different precipitations caused very high structural stress. The stress over the life span of 23 years cracked the tension ring liked with the roof panels.Then continued describing the eye shaped structure.
 * "Fluctuating stress, corrosion deteriorated Berlin hall's roof," Engineering News Record. vol. 205 no. 4 (13)**

According to the final report, the partially collapsed roof of West Berlin's Congress Hall was both due to construction and corrosion flaws.( Inadequate protection against moisture). The up and down motion of the arches caused immense tension on the steel tendons. The article then ends with a quote saying "the preponderant cause of the damage ," was the poor workmanship.
 * "Design felled Berlin roof," //Engineering News Record//. Vol. 205, no. 18 (21-22)**

Corrosion is a common failure associated with metal constructions most prominently associated with iron and steel construction. The chemical process of corrision in metals occurs in the presence of moisture. Oxide formed by oxidation of the metal does not stick to the metals surface firmly which eventually leads to structural weakness because of disintegration.
 * "Corrosion." [| http://library.kcc.hawaii.edu/external/chemistry/everyday_corrosion.html] Leeward Community College**

Corrosion is defined by the chemical reactions that take place due to oxidation in engineered materials leading to the rusting and potential cracking of the material. The rust leads to eventual instability of material, which in most cases leads to construction failures. This process is set in motion usually by the materials exposure to moisture.
 * "Corrosion." Wikipedia:The Free Encyclopedia. [| http://en.wikipedia.org/wiki/Corrosion] Wikimedia Foundation, n.d.**  **Leeward Community College**

//**F. Buchhardt, G. Magirea, W. Matthees and A. plank (1984)**// **Structural Investigation of the Berlin Congress Hall Collapse,// Concrete International vol. 6 no. 3 (63-68)** The sudden collapse of the southern arch of the Berlin Congress Hall roof prompted an investigation of the building's structural behavior. The report presented here is part of an expert's report on the failure investigation which covered structural defects, defects of the roof covering, defects of the prestressing cables and sheaths, and defects of the anchorage connections.

Figure 1 Berlin Congress Hall. Found on Google, altered using Adobe Illustrator. Original file: haus-der-kulturen-der-welt_01[1].jpg

Figure 2 Collapsed Part of Congress Hall. Found on Google, altered using Adobe Illustrator. Original file: schimetzek007_einsturz3[1].jpg

Figure 3 Close up view of Collapsed Beams. Found on Google, altered using Adobe Illustrator. Original file: schimetzek007_einsturz4[1].jpg

Figure 4 Berlin Congress Hall Rebuilt. Found of Google, altered using Adobe Illustrator. Original file: Berlin_12_CongressHall_g[1].jpg