Rohit Raj Mehndiratta and Vandini Mehta
A Recorded Lecture from FRAME Conclave 2019: Modern Heritage
In this lecture, Rohit and Vandini talk about Mahendra Raj’s journey as a Structural Designer. They also provide an in-depth insight into the structural expressiveness, innovations and elements that allowed for new spatial possibilities in his illustrious body of work.
To talk about the works of Mahendra Raj, we have titled the work, “Structural narrative of Indian Modernity as an oeuvre of Mahendra Raj” as you will see, inflects and contributes, and helped create many artefacts that pioneer the narrative of Indian Architectural Modernism post-independence.
In this presentation, we will discuss only a few of Raj’s most important projects from over 250 projects that he has realised in the last six decades. Each project that we have chosen shows a visionary and pioneering engineering solution, exemplifying the bold and adventurous innovations his practice engaged in. As we discuss these works, the underlying story that emerges is of transnational exposures and exchanges of brilliant architectural and engineering minds, Le Corbusier and Louis Khan experimenting in India, Indian architects and engineers travelling West and coming back to engage with each other and local systems, we feel, created a fertile environment and incubator of sorts for new ideas that defined Indian Modernism.
Raj’s interest in structure started in 1951 when he was appointed as the Assistant Design Engineer for the construction of Chandigarh’s High Court. The geometric parasol roof consisting of shells presented the engineers with bold structural and functional hurdles. Working with other engineers, he, with his senior Gulzar Singh proposed modifications, that of a balanced cantilever, that supported on two columns, the fins that we now see which made the construction possible. This is what Corbusier wanted, and this is what finally came about from there.
In 1953, he was given the responsibilities of completing the High Court and designing the Secretariat as an Executive Engineer. Seemingly a simple frame structure, the Secretariat was an exercise in an extremely detailed articulation of the building facade. Raj took the bold step of presenting alternatives to Le Corbusier to circumvent some of the problems that the facade of the original design presented. Here you can see the original design and what was actually built. And this was Corbusier’s design where there was nothing coming down straight and then Mr Raj actually had to go up to him and tell him that this will not work and sort of proposed a scheme which Corbusier finally accepted, and that is what you see today.
In the absence of Structural Design Education in India, he decided to go to America for further studies, and subsequently moved to New York City to work for Ammann and Whitney. Because of his Chandigarh experience, Mr Raj worked in the Special Structures Division and International Space of eager young minds that was instrumental in shaping an attitude towards Structural Design as an art form.
[05:18] Aba Tor, a colleague and close friend from Ammann and Whitney states ,”Boyd Anderson, Andy to us, was the partner in charge of the Special Structures Division. He was an inspired and inspiring engineer. He made us look at Structure as a breathing, living, dynamic moving, and sometimes even mischievous creature. We all got rid of the notion of ‘Statics’ and ‘Make It Stand Up’. Our real job was to tame the structure, allow it to move within limits without affecting its serviceability in the process”. It was this nurturing and challenging environment that Raj blossomed, where all his peers, as well as his superiors in the firm, appreciated his engineering sense and people’s skill. Raj worked on the Mohawk Hangar, a 150 feet balanced cantilever in folded plates as a Design Engineer. His next project was a 400 feet diameter concrete folded plate, which was 10 centimetres thick resting on a circumferential concrete ring for the Assembly Hall of the University of Illinois. His intuitive structural sensibilities contributed to significant design decisions, with respect to the manner ‘the folds’ were configured. During this period, he also honed his ability to work with unconventional forms in the sculptural framing of the U.S. Embassy Building in Dublin. Eventually, in early 1960, he started his practice in Mumbai.
The 1960s were exciting times for a newly Independent nation. This decade was energised by the emergence of a new generation of professionals in every field, eager to make their mark. This was an important juncture for Raj as he developed a practice that broke new grounds in the field of Architecture and Engineering. The manner Raj constantly stuck his neck out as Correa often mentioned, empowered leading architects of the country to create ‘structurally expressive forms’ through all his decades of practice despite technological and material limitations. Many of his works belong to a time where inventive use of concrete as a building material was popular the world over. In countries such as India, however, lower levels of mechanisation and cheaper construction and labour allowed unique experimentations that Raj exploited to create artefacts that are uniquely indigenous, but remarkably global in nature too.
The result, as Mark Jarzombek states, is Raj’s astonishing contribution to the history of architecture of India that has no real parallel anywhere in the world.
At the risk of simplification, we, Vandini and I, would like to discuss Raj’s work today in two categories: First, the structurally expressive buildings, many of which were large span and first of their kind in the world. Second, the innovations in structural elements that allowed new spatial possibilities. I will be taking on the large span structures.
Raj’s first project in India was the Hindustan Lever Pavilion, a temporary structure designed for the 1961 Industrial Fair in Delhi. It was inspired by ‘crumpled paper’. Raj suggested that every crumple have a definite geometric shape such as a triangle or quadrangle. Interestingly, other than an architectural plan and approximate sections, there were no drawings.
The structure was analysed, designed and detailed on the basis of a scale model alone. Raj’s structural drawings that specifies plates varying from 2.5 inches to 8 inches (I hope I am right here) along with the scale model became the dimensional base for construction on site. Notes on the drawings guided the contractor on the method of building in constant reference to the model. As inclinations of the plates could not be established until the formwork of the whole shell were erected, the concrete in the foundation could only be poured along with the shell.
The next two outstanding buildings are in ‘folded plate’ in Ahmedabad. The first is a cricket stadium for the Ahmedabad Municipal Corporation completed in 1965. What is noteworthy is the delicacy and elegance that the structure attains as a thin fold plate, rises from the ground and forms an integral whole with the spectator stands and the twenty-meter cantilever roof. Each part of the structure works with the other in fine balance. (These are images of all the options he studied before he came to the final form.)
This structure, folded plate as cantilever was first of its kind at that time. The twenty-meter cantilevered roof had a tapering fold, anchored to the folded-inclined leg that in turn combined to the seating frame.
[10:17] Both the inclined leg and the seating frame rest on a tendon-like combined strip footing. The elegance of the foundation form is because of the way the inclined allows the center of gravity of the super loads to pass through the combined strip footing and the large cantilever moment on the frame is dissipated by the time it reaches the foundation. The inclined legs of the mainframe and the seating frame were cast first and the cantilever roof was cast later in segments. After completing the entire sector, the variations in deflections were equalised by either jacking up or weighing down different folds, and then casting the front diaphragm, connecting all the folds. The notes carried all these detailed instructions.
The second project is the Tagore Memorial Hall. This performance hall takes Raj’s exploration of Folded Plate Structures further in the form of a continuous Wall and Roof system for the entire building. An independent understructure on twisted columns designed to follow the lines of stress forms a large cantilever within the foyer space. (The famous column was inspired by Nervi). The elegance and simultaneous structural efficiency emerges from the carefully proportioned trapezoidal folds, whose angles and plate thicknesses vary according to the stresses, moments and forces of the structure. Hence a depth of the vertical fold is equal to the horizontal folds when they meet each other at the top and reduces as it comes down.
More than twelve folded plate systems were explored to arrive at the optimum geometry. Clear construction notes specifying pouring sequence and support and ties that need to be provided for stability of the individual folds at different stages of concreting, until the rigid frame structure comes together was also provided. And this was the whole Camber diagram, the whole idea of how to construct in that time was in the paper, in the drawing itself.
(These are some of the construction shots)
Mahendra Raj moved his practice to Delhi in 1970 where he built the Hall of Nations in 1972, a remarkable single exhibition space of 84 by 84 meters covered with a beautiful space frame structure. It is demolished now. Normally these structures are made in steel, but since it was scarce and very expensive, Raj designed it in reinforced concrete instead.
This transition is characteristic of his open-minded creativity that he coupled with carefully guided construction practices, which were vital, given the complexity of the reinforcement at the joints of the space frame. These are the different details he made good for execution drawings, first in steel, then in precast and then finally in reinforced concrete. So he never shied away from exploration and even taking that right to the end before it had to be given up. This delicate first-ever cast-in-situ large span space frame is a Gossamer Truncated Pyramid. Our favourite part about this project, which we believe is a secret of its delicate appearance is what we call the Robust Rhombus. This was the winning section over a circle, a triangle, and many others explored. It measures a mere 25 centimetres on each side. The section helped ease the busy joints of the nine to eleven members, some in tension, some in compression, coming together with a minimum of thirty-six bars passing through each node. Raj also carefully conceptualised the stages of construction. (These are some of the calculations sheets).
This is all pre-computer time, so these mammoth structures were built without any calculator, any computer analysis. Raj also carefully conceptualised the stages of construction to help reduce the cost and effort as the entire structure was not supported with scaffolding till the roof. Based on extensive analysis, a detailed construction sequence was established. Basically, a system of scaffolding was designed; after Level 5, there was no support scaffolding needed and every layer added was a new structure and that was analysed and made sure that it is stable as a whole building went up.
[15:25] Also, remarkable was his Hindon River Mills in 1973, a structure formed by a series of elegant cast-in-situ twin concrete arches that span 48 meters and are placed at 15-meter centres. A cast-in-situ hollow post-tension girders carrying humidified air is suspended from the twin arches. Alongside in-situ construction, Precast Double T section slabs elements were cast on the ground and lifted in place with a Gantry crane that moves between the arch frames. Lateral stability for the building was provided by interconnecting the twin columns supporting the twin arches with a Folded Plate Gutter member running along the length of the building. Textile mills typically require enormous quantities of humidified air in the column-free space of the minimum possible enclosed volume to economise on the cost of air handling units. Seven alternate structural schemes were made for the initial flow diagrams and layout which required a 221 meter by 18-meter bay. At this stage, Raj conceived of a totally new structure. Finally, the client asked to revise it for a 49 by 223-meter bay. At this stage, Raj conceived of a totally new structure with Twin Arch system spanning 49 meters for which he created a comparison to show that the twin system was a more efficient resolution for structural behaviour and a more economical system despite high quantities of steel and scaffolding. This was his whole analysis, that he showed the client.
(These are some of the images, I will just quickly go through them. This is the space inside. This was the post-tensioning of the girders and the arches coming. This was the construction sequence again, very carefully designed and executed on-site. The construction also actually became an art.)
And this is the Bowstring Girders and the roof site.
Finally, the 80s also showcase one of Raj’s greatest works, the Sports Stadium in Srinagar built in 1982. With the maximum cross length of 74 meters, the Indoor Stadium was originally designed by the architects as a cross plan with central pylons to help span the roof. Mahendra Raj suggested eliminating the pylons and instead proposed a structural system that radically altered the aesthetic quality of the building while still adhering to the original intent and basic cross plan. Reminiscent – at first glance – of the Hall of Nations, the stadium is based on an entirely different concept. Both have the triangular grids, but where the hall uses a double-layered Concrete Space Frame cast in-situ, the Stadium uses a single-layered Triangulated Plates, which taper outwards from the cross-shaped base to form a continuous ridge on which rest the seating system. The building is divided into four identical units. There are seven typical plates in each unit and twenty-eight plates in the entire structure that geometrically balance each other.
Post-tensioning was also an important tool to contain High Tensile forces in some of the members. Four diagonal members forming a dramatic incline, hold the post-tension cables running through the inclined roof plates. This drawing shows how the different geometric resolutions emerged for the ending of the post-tension cables.
These are the four diagonal members that came and these are the spaces on the roof one level here, one level here, where there were post tension for the horizontal forces.
This is again a construction sequence that he designed to make sure that all four could be independently constructed and then balanced when the roof was laid.
These are some of the construction shots.
This is in Srinagar in 1982. It is way beyond its time.
And with this, I would like to invite Vandini Mehta to give insights on the structural elements and the spatial possibilities he created with that. Thank you.
[20:10] Vandini: I will continue to show buildings by Mahendra Raj which were not so overtly about the structural gymnastics or expressiveness, but instead strut subtle yet bold innovations through inventive structural solutions – solutions that help realise, and even enhance the imaginations of several architects. In these buildings, the design of structural systems and elements as also of the processes and techniques of construction that Rohit highlighted in several buildings, gave new dimensions and spans of spatial possibilities, whether it be through cleaning up dozens of columns and creating clear open spans or lifting of spaces by transferring loads elsewhere.
Going back to one of his first projects in the early 60s, the New Great Insurance building, is a six-storey office block that was constructed on an existing three-storey garage located in front of Churchgate Station in Bombay. Here the client, an architect, wanted to carry the new structure on the existing columns of the garage without knowing their strength or having any drawings of them. Instead, Raj suggested puncturing through the existing slabs and making a few additional columns that fork out to carry the columns along the periphery and corridor of the office floors above.
A completely different and more plastic design sense can be seen in the Shriram Center for Art and Culture in New Delhi. Here, the building is resolved through two distinct structural systems, a cast-in-situ drum-shaped auditorium and a 31 by 31-meter parasol roof supported on four cross-shaped columns. The final product that we see is quite different from the designs originally brought by the architect. For instance, the floating effect of the building, its notable features was introduced by the structural changes in separation that you see here of the parasol from the drum that Mr Raj suggested.
These were the two structural systems and again detailed notes. We are highlighting the notes and I guess this is something that we take much more time, maybe another lecture because I think this may have been his very distinctive way of understanding his techniques of working.
Built in 1969 in New Delhi, the Akbar Hotel’s main hotel block required a close-spaced column and beam framing configuration that the architect had to carry down into the public areas on the ground level. On Raj’s suggestion, however, these areas were reconceived as large column-free spaces achieved by introducing a transfer girder in a transitional floor above. The resultant large span column-free lobby, now a commonplace in most hotels, created a new spatial possibility. The major load of the nine floors of rooms above was now taken by this transitional flow, craftily webbed slender ribs allowed a large span to then be handled with minimal ribbed depths. The depth of the final ribs were not so much because the load was taken over by the transitional floor and also on the insistence of the architect, he wanted the columns then further to be pulled out of the structure and be expressed outside. So the web of the ribs helped him sort of bring it closer together and pull it out of the building.
(This is the transfer girder of the transitional floor. Again replete with notes and details.)
All these notes are very very precise and specific to details and points that are highlighted in this drawing. This is just highlighting one particular sequence of casting this transfer girder and the stages of constructing that which were detailed out (this is really one small section of a large drawing) and so all of this and how it fit in with the different stages was detailed out.
(To give this beautiful open space lobby and these are the rooms above.)
[25:05] The Central Bank finished the same year is a six-storey rectangular office tower emerging from a four-storeyed irregular shape podium. Deep box transfer girders, even here lift and separate the tower from the podium opening up a large unobstructed Plaza and entry above the podium.
This is the podium, and also this beautifully hung mezzanine floor. The central space inside is also the office floor that opens up. The tower stands on four corner column base with two transfer girders. These carry the floating mullion-like columns and slender ribs supporting clear floors, which are 18 meters wide and 36 meters long.
Shallower transfer girders carry a system of a Sunbreaker, so even this is supported on a system of a transfer girder, bringing this bold Modernist presence in the old city of Ahmedabad.
Prema Bhai Hall, also in the old city of Ahmedabad is defined by two exposed concrete shear walls with cantilevered ends that extend on to the street as if a flattened dinosauric form. The roof of the main 55 metres by 37 meters hall with a capacity of a thousand is supported on four-shaft columns again. Connected with deep reinforced concrete girders, the seating bowl supported on a 21-meter span deep wall-like girder clears the immense space underneath of all its originally proposed columns. The result, a dramatic and volumetrically complex foyer enriched by a structure of deep girders and wafer-thin ribs.
Raj also played the role of a structural advisor in another building in Ahmedabad; Louis Kahn’s Indian Institute of Management. Kahn envisioned the entire IIM campus in brick with the use of arches for spanning large openings. Here, Mahendra Raj’s inspired suggestion of using concrete ties to restrain the arches and take care of the outward thrust, enlarged the design vocabulary that Kahn developed at IIM.
The 80s saw further innovations. Raj designed a form that tapers from the ground up for NCDC office. Someone has likened this building to a ‘phata pyjama’. The structural resolution for shifting low transfers was resolved by very slim meandering shear walls at the outer edges of the building and parallel zigzagging columns in the center. These columns carry the box girders that tie the two inclined office wings across the building and also form the central connecting corridor.
The form created by these columns generates high tensile and compressive forces on alternate floors respectively. So this connecting corridor then becomes either a tie or a strut to hold the building together.
These are the stages of construction again, because every alternate floor which was a tie also was pre-stressed. And so how that was done and how the elongation of the cables would happen was staged and described in one of the drawings.
The earlier bare brutalist aesthetic had made the structure visible in all its glory. Now with architects using cladding and finishes to enrich aesthetics, the structure was no longer visible. However, Mr Raj still continued his zestful exploration of structural clarity.
The Vidhan Bhavan in Bhopal built on the undulating terrain of Central India is circular in its form representing the architect’s move towards prioritising materials and narrative over structural expression. Still, this building’s main programmatic spaces had bold structural forms that created a roofscape of domes, shells and a tower which bear a distinctive stamp of Raj’s contribution.
[30:22] This is the 31-meter diameter hemispherical dome, which was the main hall of the Vidhan Sabha with a varying thickness of 10 to 20 centimetres.
The triangular base of the 43 by 43 and 36 meter of the assembly halls, had sections which were weaving like a snake and the other axis was a straight line; so creating very simple yet complicated forms. A 30 meter by 30 meter lobby was opened up on the stepped column.
“The patterns of steel should always have an aesthetic quality and give the impression of being a nervous system capable of bringing life to a dead mass of concrete,” reads a quote by Pier Luigi Nervi. Nervi was an important influence in his life and this quote really brings to life what Mr Raj believed in. Mahendra Raj’s oeuvre reveals the technologies of construction in different decades emerging and innovating within and beyond the diktats of the architectural styles. Each project that we have chosen shows a visionary and pioneering engineering solution where the structure makes a bold statement and is integral to the architectural expression.
This body of work marks a significant era as it showcases the nuances of engineering, design and explorations of concrete as a new material to its possible limits, but also defying technological and material limitations within the country at that time.
Almost all these projects shown in the era of what we could now call ‘Modern Heritage’ have invented an evolved analysis and design procedures with limited or no access to computers. I want to sum up this presentation by highlighting this aspect of Mr Raj, of his innovations in process and techniques that really mark a crucial juncture in history.
The structural drawings of Mr Raj, his projects, are historical documents and we believe that they hold the key to many hidden processes and the secrets of the structures he created. Rohit and I have tried to highlight those. In addition to being works of art, they are packed with information, instructions and indefinite details revealing how tightly he controlled the building process as a very, very integral part of his design. The construction sequence, drawings and notes we found in most of the large-scale projects, if not all, particularly during the first two or three decades of his career, the 60s, 70s and 80s when it was all hand drawings and only sort of checking help of computers, become a crucial part of Raj’s work for three reasons:
First, the construction of the large span structures was a carefully staged process and meant analysing the different structures that emerged due to the changing forces and shifting loads at different stages of construction.
Second, the construction of these complex and large buildings with no previous precedents and with the rudimentary and manual construction technology of the early 60s to 80s in India required instilling an immense amount of courage and confidence in the contractors who had not attempted such buildings before, and so these became a form of very detailed communication with the contractor.
Third, the notes helped analyse and resolve issues such as economy of time, material and construction resources, and reduce the use of things like scaffolding and other materials, which were scarce at that time.
To quote Mark again, “His ability (Mr Raj’s ability) to bring to every project, the magic of engineering is what was his hallmark. His innovations are imbued with the simplicity which in his case is truly the ultimate form of sophistication; from scarcity, and with a discipline of very tight control. From his days in Chandigarh to Ammann and Whitney, to his days through the first few decades of post-Independence India, and even today as he turns 95, he will not accept any feasible solution till it challenges him to push for a clearer, more lucid way of taming those forces, and taking them delicately to the ground.
[35:30] The works represented here are a global narrative of the International style of Modernism as much as of its specific manifestations in the local conditions of India. India, we have already said this before, lacked in material and technological advancement. However, the ability of cheap labour and the undeterred Nationalist zeal and determination of the young Building professionals was really ready to create a bold vocabulary for the built environment of the newly Independent Nation.
It pushed them to stick their necks out and imagine the impossible. I am also stating this because I want to take the narrative, I think, of Post Colonial Architecture or newly Independent Architecture beyond post-Colonialism. So it is not really about only not centring the Colonial aspect of it or even of their travels to Western countries to learn. But it is that zeal which you cannot really replicate by mere education.
Mr Raj definitely went to Ammann and Whitney but his contribution in Ammann and Whitney was as significant as when he came back to India and used many of the techniques but made them his own as he did when he was working in their office.
Likewise, Corbusier was very much part of an inspiration to many young architects at his time. But in fact, it was here that he could really realise his dreams. So India was as much a space for inspiration for Corbusier as he did for the future generation. I would like to conclude here by expressing my pleasure and honour to be part of this very esteemed group, and thanking the team at Matter who has helped forge a very important tie with this thematic of this conference, and we are also very honoured and pleased because we are probably the only representatives of the engineering profession.
So, thank you.♦
Vandini Mehta is an architect and urbanist with a master’s degree from the University of California, Berkeley. After working in New York for five years, she returned to New Delhi to start Studio VanRO, a multidisciplinary practice with Rohit Raj Mehndiratta in 2007 where Vandini focuses on socially relevant architectural work and research on contemporary peripheral urbanism in Delhi and modern Indian heritage. She is a visiting faculty at SPA, Delhi engaging particularly in issues of contemporary urbanism. Vandini Mehta, Rohit Raj Mehndiratta along with Ariel Huber, co-edited the monograph titled “The Structure: Works of Mahendra Raj” published by Park Books, Zurich in 2016 which was shortlisted in the Top 3 Architecture Books (globally) in FILAF, 2017.
Rohit Raj Mehndiratta is a practising architect, artist and an urbanist. He graduated from CEPT, Ahmedabad and subsequently received a postgraduate degree from M.I.T. Cambridge after which he worked in New York for five years. Currently, he manages a multidisciplinary practice with Vandini Mehta in New Delhi, called Studio VanRO. Their architectural and research work has been widely presented, published and exhibited. “The Structure: Works of Mahendra Raj”, their co-edited book with Ariel Huber, was presented in MOMA- New York, MIT- Cambridge, ETH- Zurich, University of Lausanne, in Paris, Berlin and several cities in India. Rohit was also part of expert panel committees on Public Arts initiatives at the Delhi Urban Art Commission in 2010 and the MRTS Corridor Development subgroup formed by the Ministry of Urban Development in 2011.
FRAME is an independent, biennial professional conclave on contemporary architecture in India curated by Matter and organised in partnership with H & R Johnson (India) and Takshila Educational Society. The intent of the conclave is to provoke thought on issues that are pertinent to pedagogy and practice of architecture in India. The first edition was organised on 16th, 17th and 18th August 2019.