Annals of Warsaw University of Life Sciences - SGGW

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Annals of Warsaw University of Life Sciences – SGGW Forestry and Wood Technology No 76, 2011: 34-37 (Ann. WULS-SGGW, Forestry and Wood Technology 76, 2011) Slenderness of free sections of rafter and the shape of its cross-section as features characterizing the structures of historic roof-frames. MAREK R. GOGOLIN Institute of Technology, Kazimierz Wielki University in Bydgoszcz Abstract: Slenderness of free sections of rafter and the shape of its cross-section as features characterizing the structures of historic roof-frames. The paper presents the results of research on the selected parameters characterizing structured of roof-frames executed in the period from 13 th to 19 th century. Indicators such as the slenderness of the longest free sections of rafters and the proportions of dimensions of their cross-sections were taken into consideration and confronted with the guidelines published in old construction handbooks. It was assumed, that the analysis of those parameters will allow for defining the characteristic features of the carpenters’ workshop in the discussed period. Keywords: old roof frames, rules of calculations This is to consider geometric properties of rafters as the most weight-bearing members of every roof-frame. The proper performance of those elements is determined by such parameters as the biggest free length as well as the shape and magnitude of their crosssections. Old-times builders obviously did not know the precise rules of static calculations applied today, however they obeyed certain rules, the reminiscences of which can e found in 19 th -century construction manuals. The Menzel manual of the year 1842 1 gives simple methods of calculating the dimensions of wooden structures. It appears from the text, that for the rafter-type members the ratio between their free length to the height of cross-section – that is the slenderness of the free section – should be comprised between 18 and 20, and the ratio between the height and width of the cross-section should be from ca. 1,14 to 1,25. In another 19 th -century manual, by A. Zabierzowski 2 the rules of making such calculations have been described in more detail. Their analysis leads to a conclusion, that their starting point was the free length of a given member, and basing on that by simple calculation the height and then the width of its cross-section were reckoned. The resulting values of the discussed parameters are similar to those in Menzel’s work, equalling 16 – 20 and 1,12 – 1,17 respectively. Such differences, however small could be – which of course requires evidencing in course of separate research – a proof of slightly different approach of Polish and German builders to construction calculations. However, without going deeper into this issue, one can assume, that considering such parameters, as the ratio between the free length of a rafter section and the height of its cross-section, that is the slenderness L/h as well as the ration between the height and width of that cross-section h/b could have considerable cognitive value, giving an idea of applying defined dimensional proportions of roof-frame members by the builders. Graphic presentation of the character of variability of those parameters over the years is given in Fig. 1, in which the first diagram (a) refers to the ratio between the height and width of the cross-section of rafters, the second one (b) to the slenderness of their free sections. One can 1 Menzel C.A, Die Hölzernen Dachverbindungen in ihrem ganzen Umfange. Halle, 1842, p. 177 and further. 2 Zabierzowski A., Przewodnik praktyczny dla budujących. Warszawa, 1857, p. 269 and further. 34
notice, that over the subsequent years and centuries the b/h indicator was contained is relatively close limits 1 – 1,3 exceeding the latter value only in two cases. Fig. 1: The values of selected geometric parameters of rafters: a – h/b of cross-sections, b – slenderness of rafters The slenderness parameter changed in different way. From the late 13 th to the late 16 th century it oscillated within the 7 – 13 limit (with scarce exceptions) keeping over that period the average value of ca.10. From the mid-17 th century the range of variability of that indicator 35
Page 1 and 2: Annals Warsaw University of Life Sc
Page 3 and 4: ZIELIŃSKA-SZWAJKA JOANNA, GÓRSKI
Page 5: Board of reviewers: Bogusław Bajko
Page 8 and 9: analysis done on its base are one o
Page 10 and 11: On the base of the analysis, we sug
Page 12 and 13: Annals of Warsaw University of Life
Page 14 and 15: and analyzed on the level of tax ad
Page 16 and 17: REFERENCES: 1. Daňové trestné č
Page 18 and 19: description, selection and systemat
Page 20 and 21: Tab. 4 Regional foreign direct inve
Page 24 and 25: Опытные образцы пр
Page 26 and 27: EXPERIMENTAL PART The experimental
Page 28 and 29: 6. HENDARTO, B., SHAYAN, E., OZARSK
Page 30 and 31: Fiber direction - longitudinal Ra b
Page 32 and 33: Thickness of the paint coating film
Page 36 and 37: ises, together with its value, that
Page 40 and 41: Similar experiments were carried by
Page 42 and 43: CONCLUSION Based on the evaluation
Page 46 and 47: We can say that HC included in adhe
Page 48 and 49: 4. PARK, B.D., LEE, S.M., ROH J.K.
Page 50 and 51: plywood pressing). Spectra of liqui
Page 52 and 53: confirmed by the fact that the peak
Page 56 and 57: RESULTS AND DISCUSSION The obtained
Page 58 and 59: Streszczenie: Emisja VOC z filmów
Page 60 and 61: particleboards of 18 mm thickness l
Page 62 and 63: laminated particleboards released f
Page 66 and 67: of a rubber granulate mat, adhered
Page 68 and 69: Type of tests point I III III I III
Page 72 and 73: Parameter, unit Application method
Page 74 and 75: 3.2 Graph 3. Shear strength of glue
Page 76 and 77: property that is not directly inclu
Page 80 and 81: Die Idee, alte Papiere umzuarbeiten
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Table 1. Results of hardness tests
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cause faster and less even wear of
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Annals of Warsaw University of Life
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CH 2 OH CH CH 2 CH 2 OH CH CH 2 CH
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supply increment of the ,,j” prod
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Basierend auf der Umfrage ergaben s
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Bild 7. Standzeitdiagram - Vorschub
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ANWENDUNGEN Die Ergebnisse dieser S
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Verhältnis der maximale Durchmesse
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Basierend auf der Umfrage, für die
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drills are described in the work of
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Calculation of the thrust force and
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CONCLUSION The idea of considering
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Fig. 4. Relationship between cuttin
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life observed for MDF is longer tha
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Table 1. Types and characteristics
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ACKNOWLEDGEMENT Investigations were
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That is why a proper treatment seem
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CONCLUSIONS 1. Treatment of oil pal
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максимальной степе
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REFERENCES: 1. Шубин Г.С. Ф
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MATERIAL AND METHODS Used method We
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TVOC emitted by various kind of woo
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tensile force the dynamics of these
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Streszczenie: Gęstość drewna wia
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it was attempted in this study to a
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Cameron and Dunham [1999], when com
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unstable joints made of metal were
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Photo 8. View of an incorrect joint
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called CORDA, while the lowest cont
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willow clone, whereas the clone des
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Fig.2. Modulus of rupture of partic
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a) P, % 100 90 80 70 60 50 40 30 20
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the connection, and too little surf
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■ Multidimentional air stream wit
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Fig. 2. Proportion of elements in l
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2. The highest efficiencies were fo
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Characteristic values of annual inc
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CONCLUSIONS The following conclusio
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that of particleboards with the cor
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Streszczenie: Właściwości eksper
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across the fibres on two counterpar
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CONCLUSION Obtained results allow t
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chamber PW 10 from firm HAMECH in H
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Fig.4. RMS of F w during milling of
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Fig.4. Influence of modification on
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Fig. 2. Changes in breaking length
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Fig.5. Changes in tear strength of
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e) f) Fig. 1 Thickness changes of v
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REFERENCES 1. KAFKA, E. a kol., 198
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produce underground rhizomes and it
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It results from a comparison of the
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Alternatywne źródła energii. Dob
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качества при длите
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3 Ширина годичного
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Table 2. Basic parameters of applic
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Table 5. Test results (average valu
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a) 6 weeks 12 weeks b) 3 months 7 m
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- PN ISO 7724−2:2003 Farby i laki
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