A Basic Method for Naming Persian Karbandis Using a Set of Numbers
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- Pour Ahmadi, M. Nexus Netw J (2014) 16: 313. doi:10.1007/s00004-014-0192-x
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Identifying and recognizing the name of a karbandi especially when visiting real examples in buildings is a difficult job to do using current traditional methods. This paper sets out to introduce a new standard method for naming karbandis according to their main geometrical characteristics. The new standard uses a combination of numbers for this purpose. In this paper, after reviewing and analyzing three main sources on naming Persian karbandis, the new approach is introduced and its application is explained through some examples.
KeywordsKarbandi Traditional architecture Iran Design analysis Pirnia Sha’rbaf Lorzadeh Ribbed vault
During site visits with students to historic Persian architectural works, it was apparent that most of these students were not willing to engage with karbandis in historical constructions. Their general impression was that karbandis were too complicated to be worth examining and that it would take a lot of time and energy from them to learn about karbandis and their principles and rules.
In a close examination one may accept that the students are to some extent right about karbandis. The available resources for learning about Persian karbandis have some characteristics that make them difficult to use for ordinary readers. The language used in these resources gives the impression of being old-fashioned, complicated and relatively detached from today’s academic language. In addition, it is observed that there are some ambiguities or discrepancies in traditional definitions and methods that add to the difficulty of the job.
Considering these difficulties, this paper asks the question: “how can a new interpretation of karbandis be presented to today’s academic audience which is more user-friendly?” This is a broad problem that consists of a lot of sub-problems and depends on a lot of factors. This paper aims to solve part of this general problem.
The problem that is examined in this paper is how one can classify and name a Persian karbandi especially when one is on a site visit. The author’s hypothesis is that adoption of a pure geometrical point of view towards karbandis can be an effective approach to solve this problem. Therefore, this paper tries to introduce a new geometrical approach towards naming karbandis that is simple to use, standard, and free from the difficulties of similar traditional methods. This way, students of architecture may be able to better communicate with the concept of karbandi and work on it.
In this paper, first a literature review is conducted to recognize important features of karbandis from the viewpoint of traditional Iranian architects and to categorize the methods used to identify karbandis. After recognizing existing difficulties, the author suggests that instead of using the traditional methods, a new pure geometrical approach be adopted to classify karbandis and a set of numbers be used to name every karbandi. Finally, this new method is introduced and explained.
What is Karbandi?
Karbandi is the structure of a kind of roofing, consisting of ribs with a certain arched form which interlock according to certain geometrical rules and form the main frame of the roof. (Bozorgmehri 1992: 1).
Generally we know that the history of karbandi in Persian architecture is long. It seems that karbandi can be classified as a component of ribbed vaults.2 It is known that from about the tenth century on, ribbed vaults were used in both the Islamic and Christian world (Fuentes and Huerta 2010).
Literature on Traditional Methods of Naming Karbandis
Although there was a widespread use and a rich variety of karbandis in Persian architecture during its long history, unfortunately, the existing literature on this subject is limited. One of the difficulties arising from this condition is that our knowledge of the methods that Persian masons and architects used to identify, name and design different karbandis is in small supply.
During recent decades some books have been written about karbandis. As far as the author has searched, today there are four main books that refer to the identification and designing of karbandis in Persian architecture narrating directly from Iranian traditional architects. These books discuss the karbandis from the viewpoints of three of traditional architects.
The first book is written by Mrs. Bozorgmehri first published in 1981. As mentioned within the preface of the book (Bozorgmehri 1992), this work was based on the teachings of Master Pirniā who was an important commentator on the traditional architecture of Iran. He was from Yazd city and it can be said that his knowledge of Persian architecture is mainly tinged with his attitude towards the architecture of Yazd and the central plateau of Iran.
The second and third important books are written by Master Sha’rbāf and one of his trainees first published in 1982 and 1999 (see Sha’rbaf 2006; Pour Nāderi 1999). The last important book is based on the teachings of Master Lorzādeh written by two of his trainees first published in 1995 (Ra’ees Zadeh and Mofid 2011). These masters both lived in Tehran and their knowledge of architecture was mainly influenced by the architecture of this city.
In this paper, we will review these four books and analyze their approaches to naming karbandis. These are the books that are referred to mostly in Iran’s academic environments and students use them as reference books. In addition, with regard to the problem examined in this paper, they provide the necessary insight towards Persian karbandi, therefore the author does not go after older historical literature in order to probably find some other sources or approaches. After this we refer to the contents of these books as the viewpoints and opinions of Master Pirniā, Master Sha’rbāf, and Master Lorzādeh respectively.
Naming Karbandis According to Traditional Methods
Terminology used by the three traditional architects for naming a karbandi
As it is observed in the table, each of the master architects uses a specific set of parameters to define a karbandi. Next we will review and explain the terms in brief:
Plumb/Out of Plumb
If the slight differences between Pirnia and Sharbaf’s attitudes regarding this issue are ignored, it can be said generally that if each pair of ribs (a Tavizeh, in Farsi) are erected in a way that their two starting points (springs), and crown are located in a vertical flat surface then the resulting karbandi is a plumb kind, otherwise it will be an out of plumb one (Bozorgmehri 1992: 11; Sha’rbaf 2006: 9–10).
Number of Sides
Pirnia divides plumb karbandis into two groups based on how the points on the circumferential circle are connected to each other by line segments (Bozorgmehri 1992: 12).
First, the conventional (rasmi, in Farsi) one: the longer side of the base rectangle is set as the basis and it is considered how many segments of the circumferential circle are located between the two end points of this longer side. Then each point on the circumferential circle is connected to other points that have the same distance from it. This way a conventional karbandi is formed (Bozorgmehri 1992: 12–13).
Outline of the Base
Only Pirnia uses this feature to name karbandis. He considers some karbandis as the extended form of some basic karbandis (Bozorgmehri 1992).
Sometimes in long narrow bases, the designer had the possibility to design a full karbandi in the center and two half-karbandis of the same type on its sides. Pirnia calls the resulting vault a repetition (parvar, in Farsi) of the central karbandi (Bozorgmehri 1992).
It seems that if a karbandi has an apparent cross-shaped composition, Pirnia regards it as two interlaced (dar-ham, in Farsi) extended types of a basic karbandi (Bozorgmehri 1992).
In Pirnia’s method usually no need is felt to mention this feature because when the shape of the base is exactly stated it usually, but not always, implies that the karbandi is one-footed or two-footed.
Surprisingly, there is a discrepancy between Lorzadeh’s definition and Sharbaf’s definition of this quality. In some cases what is called a one-footed karbandi in Sharbaf’s method is called two-footed by Lorzadeh (see Table 1, item no. 16).
Broken Filter Tip
In Lorzadeh’s method if a basic karbandi is extended in three or four directions as far as two or four squinches are created at its corners, the resulting karbandi is called a karbandi with squinches (Ra’ees Zādeh and Mofid 2011: 37). It is clear that a karbandi that has squinches, has soosans too (Fig. 11).
Note that, a squinch is called a ‘filgoosh’—which means elephant ear—by Lorzadeh, while it is called ‘haft’ or ‘hafti’—which means ‘seven’—in Sharbaf’s terminology (Sha’rbaf 2006: 94).
When explaining nimkār (semi-work) karbandis, Lorzādeh divides them into three groups. This division is derived from the ratio of the depth of the base to the front side (or span) of the base.
The third group of nimkārs are ones within which the depth of the base is smaller than a half length of the span. According to Lorzadeh these nimkārs can be of two kinds: first, shallow (tonok, in Farsi) nimkārs; second, two-footed nimkārs (Ra’ees Zādeh and Mofid 2011: 42).
The Need for a New Standard Method for Naming Karbandis
By reviewing the literature, we can see that although these sources provide us with invaluable information about karbandis, there are some difficulties concerning the methods used by these master architects to name karbandis.
They usually lack a systematic approach to explain the terms, subjects, and methods. All three books have a case-based structure in which different karbandis are introduced one by one and do not try to organize the cases in a clear order. And because of their quality of being of few words, the reader of these books must usually deduce from the plans what is really meant by some titles. Furthermore, there are occasions where a lack of scientific rigor is observed. For example, in both Pirnia and Sharbaf’s methods there is a discrepancy in titling some cases as plumb or out of plumb and they do not define this quality in a consistent way.
There is a great emphasis on memorizing technical terms. This approach makes the understanding of karbandis unattractive for today’s audience, among them architecture students, and hinders their close relation with karbandis. However, the terms used to name karbandis belong to a past culture. Although it uses some nice terms that echo a traditional mind set and a close relation to nature, there is a need to update them.
The traditional approaches taken to name karbandis are deeply construction-oriented and technological limitations of the time have influenced the whole notion of karbandi. Today’s architecture students and designers need not think of karbandis within all those constraints. They can define karbandis using a freer approach.
Therefore, the need for a standard method to name karbandis is noticeable. The author suggests that a pure geometrical approach be taken to define and classify karbandis in a more user-friendly and up-to-date manner.
The New Geometrical Method to Classify Karbandis
In this section the new geometrical method to name karbandis is introduced. First, a geometrical explanation of karbandis is presented. Then the new method is explained step by step.
Karbandi from a Geometrical Point of View
In every basic star a number of concentric circles can be defined (Fig. 17). Hereafter they will be called “circumferential circles”. We will use these circles later to name karbandis.
First, karbandis in which the four corners of the base rectangle sit on four vertices of a circumferential circle. The resulted karbandis, using the terminology of Sharbaf, are called one-footed karbandis (Figs. 18, 19).
Second, in contrast to the previous group, in this group of karbandis the corners of the base rectangle are not located on vertices of any circumferential circle; instead there are two vertices on the sides of each corner (Figs. 21, 22). These karbandis are called two-footed in Sharbaf’s method.
The New Geometrical Method
In this section a new method for classification of karbandis will be introduced step by step. In this method a set of numbers which are arranged in a specific order is used to identify and name each karbandi. Therefore, in contrast to the traditional methods, there is no need to use a long combination of difficult technical terms for this purpose.
Step 1 is the recognition of the specific basic star used in the karbandi. To do that one can simply count the number of sides of the shamseh or if it has the shape of a star-polygon, one can count the number of its wings. Note that the full shamseh is the basis for counting; for example, in nimkārs the whole shamseh should be considered, not the existing half of it. So, the first number to name a karbandi is determined.
Step 2 is in relation to whether the karbandi is a plumb kind or not. Pirnia and Sharbaf mentioned this characteristic but Lorzadeh did not. Here we define this characteristic in a simple geometrical way. Geometrical description of this characteristic refers to the horizontal angle between every two ribs that join and form a pair of ribs. This angle determines the second number in naming a karbandi.
When looking at a real karbandi, if the observer does not have the ability to measure the exact angle, he can just discern whether the angle is 180° or smaller. If it is smaller than 180° then one can use the symbol “<180” instead of the exact angle in naming the karbandi. This approach will be equivalent to Pirnia and Sharbaf’s approach towards out of plumb karbandis.
The problem with his method is that the recognition of this number is very difficult when one looks at a real karbandi and tries to find the number. In addition, it does not define different karbandis that originate from a single basic star in a continuous geometrical relation to each other. It defines them as separate items in a segmented approach based on memorizing the samples.8
At Step 3, the third number determining the name of the karbandi is calculated. Here the identification of a karbandi is almost complete and its main features are determined, but if one wants to specify the exact shape of the base, he should continue to the next step and complete the process.
Some Practical Examples
Having explained the new method, in this section some practical examples are presented to better demonstrate the performance of this method. First, a comparison has been made between the new suggested and traditional methods of naming karbandis on two examples of karbandis: one from Pirnia’s book and another from Sharbaf’s. The relative simplicity of the new method can be considered by this comparison. Next, using the photo of a real karbandi, it is demonstrated that how one can find its name.
In this paper a new geometrical method for naming karbandis was presented in response to the problem that was observed in this respect. The author believes that by using this geometrical method one can more easily identify and name karbandis when studying Persian architecture and especially when visiting its works on site. It helps to standardize the method of identifying karbandis and resolves some difficulties arising from scattered traditional methods.
For the time being, this geometrical approach can be considered as a complementary method along with traditional methods to streamline our understanding of karbandis. In fact, it only concentrates on the main characteristics of karbandis and more detailed and creative variations in karbandis are out of the scope of this primary method. However, by providing a new point of view towards karbandis, it may facilitate the departure from the old concept of karbandi and pave the way for a new status for it in contemporary architecture.
It should be mentioned that the karbandi was not always used as the main load-bearing structure of the roofing system. Sometimes they are just superficial coverings for the main load-bearing structures of the roof.
However, conclusive statement on this issue needs more investigation.
Concerning the approach taken in translating the Persian terms into English a point should be mentioned. There may be some elements in Persian karbandi that have similar counterparts in European architecture that have a specific name in English. In these cases, the relevant English word is used to name that element of karbandi. For example, “rib” is used for “tavizeh” and “squinch” for “filgoosh”. But in most cases the elements or characteristics of Persian karbandi as they were defined by Persian architects, do not have any counterpart in English architecture i.e., the European architects did not use technical words to name them. Therefore, there is not a specific word in English that can be simply used in translation. Here, as far as the author knows, three main approaches can be taken: First, transliteration i.e., to use the exact Persian term in English and not change it at all, as is the case for the very term “karbandi”. Second, to translate literally the Persian terms into English; for instance, to use the word “thin-footed” for “pa-barik”. Third approach is by considering the Persian term and trying to find a higher level of abstraction or giving a kind of interpretation for it; then translating the abstracted definition or interpretation into English. This is the approach that is taken by for example professor Necipoglu when she names the cells of Persian girih works (1995). Through a geometrical interpretation, she uses “kite-shaped rhomboid” for “toranj” and “ten pointed composite polygon” for the “sorme-dān” cell which means “kohl container” in Farsi (Ibid). In this paper the third approach could not be suitable, since the main claim of the research is that the original system of naming karbandis has difficulties and needs to be upgraded and redefined in today's language. Therefore, it seems reasonable to use the original terms or their literal translation when the paper is describing the difficulties of traditional methods.
Pirnia explains this condition in this way: that the butterfly cells (Shaparaki, in Farsi) adjacent to the Shamseh are omitted (Bozorgmehri 1992: 40). So, he disregards the fact that the ribs are not self-stable any longer and the karbandi must be called out of plumb according to his own definition. Therefore, it seems that in reality the method of drawing the ribs and the size of the Shamseh of a karbandi is more important a factor in defining which kind it is. But the traditional masters do not explain it in this way.
It should be acknowledged that these three masters’ understanding of karbandis was certainly more than just what was written in these books. Their practice and prominent works testify to their expertise. But here we are just speaking about their books and what is written there.
Attention should be given to the fact that all of the resulted karbandis were not necessarily used in traditional architecture. Here we do not have an intention to take into account practical and other considerations of traditional architects.
This discrete approach to introducing karbandis is the main difficulty of Pirnia's method. Even by saying that a karbandi is an extension of another karbandi or an interlaced extension of two other karbandis the complicatedness of the problem is not reduced.
Shish-e koochak va bozorg (in Farsi): the name for a certain type of hexagon.
These toranjs may be called by some traditional architects “shaparak” which means “butterfly”.