Building construction
long span structure
SUBMITTED TO: AR. SHOBHIKA
SUBMITTED BY: DHARNA GARG B. ARCH. 7 SEM. ROLL NO. 1221009
Introduction of hall of nation LOCATION: NEW DELHI, DELHI, INDIA PROJECT COMPLETED: 1972 AN INTERNATIONAL TRADE FAIR TO BE HELD AT NEW DELHI IN 1972, REQUIRED LARGE EXHIBITION HALLS.
THE PERMANENT EXHIBITION COMPLEX IS DESIGNED TO FORM THE FOCUS OF 130 ACRES OF EXHIBITION GROUND DESIGNED BY RAJ REWAL IN NEW DELHI. THE DESIGN WAS EVOLVED TO MEET THE CONSTRAINTS OF TIME, AVAILABILITY OF MATERIALS AND LABOUR, BUT ABOVE ALL, TO REFLECT SYMBOLICALLY AND TECHNOLOGICALLY, INDIA'S INTERMEDIATE TECHNOLOGY IN THE 25TH YEAR OF ITS INDEPENDENCE. THE DEPTH OF THE STRUCTURAL SYSTEM WAS UTILIZED AS A SUN BREAKER AND CONCEIVED OF IN TERMS OF THE TRADITIONAL 'JALI', A GEOMETRICAL PATTERN OF PERFORATION THAT SERVES TO OBSTRUCT DIRECTS RAYS OF THE HARSH SUN WHILE PERMITTING AIR CIRCULATION. THE MAIN PAVILION OF THE HALL OF NATIONS HAS A CLEAR SPAN OF 78 METRES AND A HEIGHT VARYING FROM THREE METRES TO 21 METRES, THEREBY PROVIDING A VAST CAPACITY FOR ITEMS TO BE EXHIBITED, FROM BOOKS TO BULLDOZERS. THE MAIN HALL IS REQUIRED TO HAVE A FREE AND UNOBS TRUCTED SPACE OF 670 SQ. M. WITH AN APPROPRIATE HEIGHT OF 30 M. AND WAS NAMED AS “HALL OF NATIONS”.
SHAPE AND FORM FOR COVERING SUH A LARGE AREA SEVERAL OPTIONS E.G. SHELLS, FOLDED LATES, HYPAR SHELLS WERE CONSIDERD AND REJECTED ON THE GROUND OF ECNOMICS. EVENTUALLY THE SOLUTION NARROWED DOWN TO A DOUBLE LAYERED SPACE FRAME.. THE HALL OD DIMENSIONS HAVE A BASE DIMENSION OF 73 M X73 M. WHICH REDUCED TO ALMOST HALF AT THE ROOF. WHILE THE INVESTIGATING THE CONFIGURATION OF SPACE FRAME IT WAS IDENTIFIED THAT THE MOST APPRORIATE SYSTEM TO CREATE SPACE FRAME WAS THE ONE WHICH USED PYRAMID AS A BASIC ELEMENT.
STEEL AND CONCRETE WERE GIVEN DUE CONSIDERATION AND IT WAS FOUND THAT CONCRETE WAAS THE MST ECONOMICAL MATERIAL , WITH STRUCTURAL STEEL BEING 30% MORE EXPENSIVE.THUS CONCRETE WAS THE FINAL CHOICE.
FOR CLADDING, GUNITED TRIANGULAR PLATES WERE PROVIDED WHILE ROOF OF THE HALL WAS COVERED WITH THE PRECAST LIGHT WEIGHT CONCRETE PLANKS.
DESIGN AND ANALYSIS
A STUDY OF THE CONFIGURATION REVEALED TE STRUCTURE WOULD BE STABLE ONLY AFTER CONSTRUCTION HAD REACHED AT LEVEL , WHERE IT RECEIVED THE FIRST AROUND CONTINUITY AND BEFORE THAT IT WOULD REST ON SCAFFOLDING ERECTED FROM GROUND. HOWEVER THIS RESULTED IN FIVE DIFFERENT CONFIGURATIONS WITH INTRODUCTION OF EACH ADDITIONAL RING BEYOND LEVEL 5. THEREFORE ANALYSIS WAS CARRIED OUT FOR ALL FIVE DIFFERENT CONFIGURATION TO FIX FINAL MEMBER SIZES
DESIGN AND ANALYSIS THE ANALYSIS WAS DONE ASSUMING PINNED JOINTS , AS THE MEMBER WERE SLENDER AND IT WAS BELIEVED THAT SIGNIFICAT MOMENTS WOULD NOT DEVELOPED . AN INDEPENDENT ANALYSIS DONE LATER CONFIRMED THIS ASSUMPTION AS THE MOMENTS IN MEMBERS VERY SMALL. THE SPACE FRAME WAS ANALYSED FOR EARTHQUAKE AND WINDLOADS USING A THREE DIMENSIONAL PLAN JOINTED MODEL.MOST IMPORTANT POINT FOR SELECTING A MEMBER SHAPE WAS STRENGTH AND EASE OF FABRCATION . SEVERAL ALTERNATIVES FOR MEMBERS SECTION WERE CONSIDERED AND FINALLY A RHOMBIC SECTION
WITH CHAMFERED EDGES HAVING AN AREA OF 585 SQ. CM WAS ADOPTED THE ANALYSIS WAS REVELEAD THAT HORIZANTALL
REFELCTIONS OF NODES NEAR CENTRAL LINES SYMMETRY WOULD BE LARGE . TO CONTAIN THERE REFLECTIONS, HORIZANTALL DIAPHRAGMS WERE INTRODUCED BETWEEN INNER AND OUTER FACES OF THE SPACE FRQAME AT LEVEL 3,6,8. THE OBVIOUS CHOICE OF CONSTRUCTION WAS PRECAAST CONSTRUCTION TECHNIQUE . IT WAS VISUALLISED THAT THE MEMBERS AND JOINT WOULD BE PRECAST SEPERATELY AND PUT TOGETHER WITH HELP OF BOLTS AND FILLED WELDING OF SHIM PLATES . DETAILS OF SUCH PRECAST JOINT ARE SHOWN IN FIG. UNFORTUNATELY NO CONTRACTOR CAME FORWARD TO CONTSRUCT THIS STRUCTURE USING PRECAST TECHNIQUE , HENCE INSITU CONCRETE WAS ADOPTED . THE DEVELOPMENT OF INSITU JOINT WAS DIFFICULT OWING TO CONGESTION OF
BARS AT THE JOINT ELEMENT . ON AN AVG. , 9 MEMBERS MET AT ONE JOINT AND EVEN WITH 4 BARS PER MEMBERS ,
DESIGN AND ANALYSIS THERE WOULD BE 36 BARS MEETING AT THE JOINT , SOME CARRYING TENSION WHILE OTHERS WERE IN COMPRESSION. IN THE PRECAST JOINT SOME ASSISTANCE WAS AVAILABLE FROM STEEL PLATES EMBEDDED IN
CONCRETE BUT IN THE INSITU JOINT THAT WOULDNOT BE POSSIBLE .
FINALLY A SYSTEM WAS EVOLVED WHERE ONLY 20 BARS PASSED THROUGH THE JOINT ELEMENT .BARS FROM LOWER 4 MEMBERS WERE LAPPED WITH 4 UPPER MEMBERS BARS THUS CATERING TO 8 MEMBERS . THE SEQUENCE OF CONSRUCTION WAS TO CAST STRAIGHT LENGTH OF MEMBERS FROM JOINT TO JOINT , PLACE IN POSITION PARTIALLY PREASSEMBLED FORM WORK OF THE JOINT ALONG WITH PLACED IN POSITION SHORT LENGTH CURVED BARS .T THESE BARS WERE WELDED WITH STRAIGHT BARS OF MEMBERS , FORMWORK OF THEMEMBER UPTO NEXT JOIT ERECTED AND THE MEMBER AND THE JOINT CONCRETED .
THIS SEQUENCE WAS FOLLOWED UPTO ROOF LEVEL THE CONSTRUCTION OF SPACEFRAME WAS TAKEN ON ALL 4 SIDES SIMULTANEOUSLY .
plan
THE PLAN OF THESE PAVILIONS IS SQUARE WITH CHAMFERED CORNERS , PROVIDING EIGHT ANCHORING POINTS. THE CORNERS WERE INSPIRED BY THE TOMB OF MUGHUL EMPEROR HUMAYUN'S AND THE TAJ MAHAL. IN THE HALL OF NATIONS AN UNINTERRUTED VOLUME IS ACHIEVED WHERE THE HEIGHT VARIES FROM 3 M TO 30 M. THIS PERMITS THE DISPLAY OF SUCH DIVERSE OBJECTS AS AIRCRAFT, EARTHMOVING EQUIPMENT, TRACTORS AND CRANES. IN THE HALL OF INDUSTRIES THE HEIGHT VARIES FROM 2.5 M TO 15 M. THE SQUARE PLAN ADOPTED PERMITS ADDITIOINAL UNITS TO BE ADDED AS NEEDED.
Cross -section of Nehru pavilion
