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Proceedings of the 9th International Conference on New Trends in Statics and Dynamics of Buildings

October 20-21, 2011 Bratislava, Slovakia Faculty of Civil Engineering STU Bratislava

Slovak Society of Mechanics SAS

ACHILLES’ HEEL OF THE ABM 12O DOUBLE CORRUGATED PROFILES

R. Walentyński1, R. Cybulski2 and K. Kozieł3

Abstract This paper describes briefly the ABM (Automatic Building Machine) technology which can be used as a solution for buildings and roofing structures. It is a factory on wheels that makes cold-formed arch steel buildings in a very short time period as self-supporting panels. The main problem of such structures lies in the lack of proper theoretical model of the panel due to its complex geometry. In order to understand the panel behavior, which in the future will give a starting point for theoretical model construction, four laboratory tests under different load conditions were performed. The main goal of this paper is to show the common failure form of each sample which is called by the authors “Achilles’ hell”.

1 INTRODUCTION Due to today’s difficult economy, cheap and short time consuming solutions for buildings industry are very desirable. One of the solution which fulfills above requirements is the ABM (Automatic Building Machine) technology. It is a mobile factory used to fabricate and construct K-span arch steel buildings based on self-supporting panels (MIC 120 profiles). This technology comes from the USA and belongs to M.I.C. Industries Inc.[4]. The ABM technology consists of a movable, steel building manufacturing plant, known as the MIC 120 System. This machine is placed on a trailer, forming factory on wheels which can be easily transported to any construction sites (see Fig. 1). Once, the machine is delivered to site, the construction process can be started be a small group of trained crew.

Fig. 1. ABM MIC 120- movable manufacturing plant

1 Associate Prof. R. Walentyńśki, The Silesian University of Technology, Faculty of Civil Engineering, Akademicka 5, 44-100 Gliwice, Poland, 0048 (32)2372118, [email protected]. 2 MSc Eng. R. Cybulski, The Silesian University of Technology, Faculty of Civil Engineering, Akademicka 5, 44-100 Gliwice, Poland, [email protected]. 3 MSc K. Kozieł, The Silesian University of Technology, Faculty of Civil Engineering, Akademicka 5, 44-100 Gliwice, Poland, [email protected].

9th International Conference on New Trends in Statics and Dynamics of Buildings October 2011, Bratislava

Firstly, coils of steel are formed to the straight panels shown in Fig. 2. This panel is cut to achieve needed span of the future arch building.

Fig. 2. ABM MIC 120 straight section

Secondly, these panels are bent to form the arch and their shape changes to the one presented in Fig. 3.

Fig. 3. ABM MIC 120 channel section

The scheme of panels prefabrication process is shown in Fig. 4.

Fig. 4. Panels prefabrication process

Few single panels are tight together by the seam machine to form groups of panels which are fixed to lifting sling and transported to the execution place by a crane (see Fig. 5).


Fig. 5. Panels assembly After that these panels’ groups are machine seamed together, they form an economical and waterproof steel structure. Fig. 6 presents the last step of arch construction process.

Fig. 6. Steel buildings in ABM technology

This technology became popular in civilian life all over the world. The examples of ready K-span arch steel buildings are presented in Fig.7.

Fig. 7. Steel buildings in ABM technology: upper row- Pietrowice (Poland), Pawłów (Poland), bottom row- South Korea


More detailed construction process is described in references [1], [3], [5]. There is no proper theoretical panel‘s model and surfaces corrugations created during panels bent into an arch are also not well understood. The above problems leaded in past years to few collapses of such structures. One of these collapses took place in Gdańsk in Poland (see Fig. 8). The collapse process was following: ready building has some initial damages of panels flanges at the roof ridge and after intense snowing the load on roof increased (building was not heated in that time) and caused the arch building failure. This is a reason for providing the experimental investigations of ABM MIC 120 panels and forms of failure during the tests are presented herein.

Fig. 8. ABM arch steel building in Gdańsk before and after collapse


2 EXPERIMENTAL INVESTIGATION In this section samples’ experimental tests are shortly discussed based on experience achieved form references [7] and [8]. Four different tests were carried out: axial compression (three samples with length L=60cm), eccentrically loaded compression (three samples with length L=60cm), bending test- upper part of cross-section in compression (arch samples with length L=400cm and rise of arch r=15,8cm), bending test- bottom part of cross-section in compression (arch samples with length L=400cm and rise of arch r=15,8cm). Steel of grade S280GD was used to fabricate panels’ samples.

2.1 Compression tests Compression tests were conducted in hydraulic press. To each sample, thick metal plates were fixed due to loading transfer. On one end this plate was 12mm thick and the other 2x12mm. Cup-and-ball joint was installed between pair of plates (2x12mm) and hydraulic press. Cross-bars were also screwed down to samples in order to improve their local instabilities properties. Loading was performed in steps 0kN-5kN-0kN-10kN-0kN-15kN till samples failure. In order to measure the samples shortening, displacement sensor was fixed between non-movable and movable parts of hydraulic press. The experimental investigations results were collected by the computer, which was connected to the test stand.

2.1.1 Axial compression

The test stand (Test 1) with connected computer and destroyed samples are presented in Fig. 9 and 10. The average ultimate load equal to 37.6 kN was achieved. Load from hydraulic press was applied at the gravity centre of cross-section.

Fig. 9. Axial compression test stand with connected computer


Fig. 10. Samples after axial compression

Diagrams presented in Fig.11 shows the relation between forces and axial displacements for each sample. From the curvatures’ shapes it can be observed that all three samples behave in the same way, furthermore it can be concluded that axial compression test was performed for each sample with similar accuracy. Failure of samples occurred due to material’s plastic deformations.

Fig. 11. Axial compression test- force vs. displacement diagrams

2.1.2 Eccentrically loaded compression

The test stand for eccentrically loaded compression (Test 2) investigation was exactly the same as in previous section. Deformed shapes of three samples are shown in Fig. 12. The average ultimate load obtained in this test


is equal to 27.4 kN. Load from hydraulic press was applied 0.2 cm form the curved bottom edge in order to achieve compression at the web of the cross-section.

Fig. 12. Destroyed samples of eccentrically loaded compression test

Fig.13 shows the relation between forces and axial displacements for each sample. The same conclusions as in previous section are valid for eccentrically laded compression tests. It is also stated that in present case, the test was performed for each sample with similar accuracy. Failure of samples occurred due to material plastic deformations.

Fig. 13. Eccentrically loaded compression test- force vs. displacement diagrams

2.2 Bending tests Let’s consider basic load on arch structure as symmetric snow load. The bending moment distribution in such case is presented in Fig.14.

Fig. 14. Bending moment distribution from symmetric snow load case


From Fig.14 known phenomenon is observed that along the length of arch, once the flat lips of cross-section are in compression and in the other place the cross-section’s webs are in compression. This is a reason for preparing two bending tests described later herein. Bending tests were conducted on samples using hydraulic pump for loading purposes. Each sample was built from six single panels. The static scheme was assumed as simply supported arch. Loading was performed in steps 0kN-5kN-0kN-10kN-0kN-15kN till samples failure. In order to measure deflections of the arches, rows of displacement sensors were installed and connected to computer.

2.2.1 Bending test with flat lips in compression

Firstly, bending test with flat lips in compression (Test 3) was performed. Fig. 15 presents photo and scheme of the test stand. The ultimate load equal 21,7 kN was achieved. This load responds to the bending moment which equals 2.61 kNm. The load-displacement path is presented in Fig.16.

Fig. 15. Bending test stands- Test 3

From Fig. 16 it is observed that arch was destroyed in the material’s elastic range (due to lose of flanges stability- will be explained in the next section).


Fig. 16. Load- displacement curve- Test 3

2.2.2 Bending test with webs in compression

Secondly, bending test with webs in compression (Test 4) was conducted. Fig. 17 presents photo and scheme of the test stand. The achieved ultimate load equals to 24,0 kN and responds to the value of bending moment equal to 2.9 kNm. The load-displacement curve is presented in Fig.18.

Fig. 17. Bending test stands- Test 4 Fig. 18 shows that arch element achieved failure in the material plastic range. Such experimental investigation should be repeated on many samples in order to give more convincing conclusions and observation. These tests have only informative purpose and are treated as introduction to experimental investigation.


Fig. 18. Load- displacement curve- Test 4

3 FORMS OF FAILURE AND CONCLUSIONS The forms of failure of samples from each experimental investigation (Tests 1÷4) are shown in Fig.19. It is observed from the Test 3 that failure started from deformation of flat lips and moved to flanges by loss of stability in material’s elastic range. In case of Tests 1, 2 and 4, failure forms occurred due to deformation of corrugations in material’s plastic range. This deformations always started at the places where peak of web’s corrugation and peak of flange’s corrugation were positioned in the same plane. Such places where both corrugations peaks are situated in the same plane repeat every 51 cm along panels’ length. This kind of failure form of ABM MIC 120 profiles is called by author the “Achilles’ heel” due to its weak point of prefabrication process. In this paper only experimental results are presented. The introduction to numerical analysis of such panels is discussed in reference [6]. As for the future work, the following problems must be solved in order to use this system safely in Europe. According to authors knowledge, all calculations are made according to American design codes. This gives a series limitation of use of this system in Europe due to different loads consideration. Also, there is no proper theoretical panel model and surfaces corrugations created during panels bent into arch is not well understood. European standards recommend to treat ABM panel’s cross-section as class 4. So it means that corrugated surfaces are not taken into calculation process. It is not totally correct especially that folding gives some resistance to local buckling. This statement seems to be right especially when we see failures forms from Test 1. Due to axial compression the ABM MIC 120 cross-section deformed in the material’s plastic range and there is no sign of typical plate local buckling behavior. In order to prove above conclusions, panel with shape presented in Fig. 2 will be subjected to axial load and results will be compared with those form Test 1.


Fig. 19. Forms of failure

ACKNOWLEDGEMENT We would like to show our gratitude to “Konsorcjum Hale Stalowe”[2] firm for supplying us with necessary knowledge about ABM MIC 120 technology and panels’ samples for experimental investigation.


REFERENCES

[1] Cybulski, A.- Kozieł, K.: Introduction to stiffness investigation of ABM K-span arch structures. InterTech 2011 Conference, Poznań.

[2] Konsorcjum Hale Stalowe. http://www.ptech.pl

[3] Kowal, A.: Dachy dużej rozpiętości z blachy fałdowej w technologii ABM. Materiały Budowlane, Vol.6, No. 454, 2010, p.7-8 (in Polish).

[4] M.I.C. Industries Inc. http://www.micindustries.com

[5] Walentyński, R.: Design problems of cold formed light weight ark structures. Local seminar of IACC Polish Chapter, 2004.

[6] Walentyński, R.- Cybulski, R.-Kozieł, K.: Numerical models of ABM K-span steel arch panels. After positive review, will be published in Architecture Civil Engineering Environment, January 2012.

[7] Wu, L.- Gao, X.- Shi, Y.- Wang, Y.: Theoretical and experimental study on interactive local buckling of arch-shaped corrugated steel roof. Steel Structures 6 (2006), p. 45-54.

[8] Xu, L.- Gong, Y.- Guo, P.: Compressive tests of cold-formed steel curved panels. Journal of Constructional Steel Research 57 (2001), p. 1249-1265.

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