Design-Construction Feature i^he Jordan River Temple Tower Spire
Victor Roblez Chief Engineer Buehner Concrete Salt Lake City, Utah
Presents the design, fabrication and erection highlights of the Jordan River Temple tower spire in Salt Lake City, Utah. A major feature of this project was the use of glass fiber reinforced concrete to clad the tower spire.
he Church of Jesus Christ of these towers and spires. In fact, these T Latter-Day Saints (the Mormons) considerations, in addition to design are temple builders by religious con- preference, have dictated the combina- viction. In as much as the temples are tion of several cladding materials. monument-type structures, they are The Washington, D.C., Temple (Fig. typically clad with marble, granite, or 1) has the main structure clad with architectural precast concrete. One of marble-clad precast concrete panels. the distinguishing features of the tem- The six towers are clad to match the ples is one or more towers and spires. main structure while the spires are clad The height and location of the tower with fused-on gold porcelain. spires have always posed severe weight The main structure of the Seattle, restrictions on the cladding selected for Washington, Temple (Fig. 2) is clad
32 The Jordan River Temple, Salt Lake City, Utah. (Photo courtesy of the LDS Church.) with conventional exposed aggregate The Ogden, Utah, Temple (Fig. 3) precast concrete panels. The tower is has white exposed aggregate precast clad with a similar exposed aggregate concrete panels cladding the main precast panel, but manufactured in 2 in. structure. However, the design concept (51 mm) thick sections. The spire is of the tower did not permit the use of made of anodized aluminum. thin small sections. The single centrally On both of these towers, the design located tower required long crane concept permitted the use of thin, flat, reaches during erection, thereby im- small sections of marble and/or precast posing strict weight restrictions on the concrete thereby allowing the sections cladding material. Glass fiber rein- to remain relatively light to facilitate forced plastic with an anodized alumi- manufacturing, handling, and erection. num filial was selected for the tower.
PCI JOURNAL/September-October 1982 33 Fig. 1. Washington, D.C. Temple. (Photo Fig. 2. Seattle, Washington Temple. courtesty of the LDS Church.) (Photo courtesy of the LDS Church.)
Fig. 3. Ogden, Utah Temple. (Photo courtesy of the LDS Church.)
34 Ir
Fig. 4. Architect's rendering of Jordan River Temple.
Architectural Concept Design Solution During the conceptual stage of the The parameters for the material be- Jordan River Temple (Fig. 4) [located came readily apparent: a material with approximately 15 miles (24 km) south of high moldability; a material that would Salt Lake City, Utah], Mr. Emil Fetzer, duplicate the exposed aggregate finish Director of the LDS Church Temple used to clad the main structure; a mate- Architectural Department, chose to clad rial with inherent light weight to the main structure with white exposed minimize the loading on the roof and to aggregate panels. facilitate erection. The size and weight The corner panels are flat with level of the panels were strictly governed by parapets. The panels located in the the cranes available in the Salt Lake center of the building are lightly City area. sculptured horizontally, while the ver- The configuration of the cladding, in tically sculptured parapet serves as an addition to the weight considerations, introduction to the tower spire. The precluded the use of small thin precast single centrally located tower spire is concrete panels, which in effect elimi- exotically sculptured, which em- nated precast concrete. phasizes the ribs in order to emulate Class fiber reinforced concrete the hill and valley Wasatch Mountain (GFRC), a material that fulfilled all the backdrop. design parameters, was selected to clad The design preference was to clad the tower spire. Once GFRC was se- the tower spire with an exposed aggre- lected, the decision was made to dupli- gate matching the exposure on the main cate the precast exposure with a 1/a in, building panels. (13 mm) thick facing mix backed with a
PCI JOURVALJSeptember-October 1982 35 ^ in. (10 mm) thick GFRC skin yield- quality of the mold determines in a ing a total skin thickness of 7/a in. (22 large measure the quality of the fin- mm). ished product. The tower spire was no The skin is reinforced with hollow exception and much of the cost and GFRC box ribs, % in. (10 mm) thick, of time in producing this cladding was in- varying width, depth, and spacing to vested in mold fabrication. suit panel size and structural require- All of the molds were fabricated on ments. The weight of the panels proved structural steel reinforced plywood to be 15 to 20 psf (0.72 to 0.96 kPa) or pallets. The flat panels simply required approximately one-fourth the weight of fiberglass coated plywood formwork. similar precast concrete panels. The sculptured molds were plywood ribbed with the plywood skin molded Design Features to the rib shape and then fiberglass The Jordan River Temple tower spire coated (Figs. 9 and 10). is composed of a steel truss frame sup- The tower and spire control points ported upon a reinforced concrete roof were established and the sculptured clad with GFRC panels. The tower panel curves, vertical and horizontal, spire rises 141 ft 9 in. (43.1 m) from a were determined mathematically using roof height of 58 ft (17.7 m), for a total the curve-fitting method to the power height from grade of 199 ft 9 in. (60.9 curve Y = ax e'. The power curve m). achieved the "teardrop" appearance The tower portion is composed of desired by the architect, three vertical tiers. The first tier is a Since the tower was vertical, only single course of panels 20 ft 6 in. (6.25 one curve was required for each differ- m) high bearing on a cast-in-place curb ent tower shape. The curve was deter- and tied back at the top. The panels are mined, furnished to the mold shop, and set to an outside radius of 31 ft 4 in. the plywood ribs cut to that shape. (9.55 m) (see Fig. 5). The first tower tier required 40 The second tier is also a single course panels taken from 24 basic shapes. The 20 ft 6 in. (6.25 in) high supported in second tower tier required 32 panels the same manner as the first tier, but set taken from 20 basic shapes. These two tiers required pallets 12 ft (3.66 m) to an outside radius of 23 ft 3% in. (7.10 m) (see Fig. 6). wide by 25 ft (7.62 m) long. The third tier is composed of three The third tier, consisting of three courses totaling 49 ft 5 in. (15.1 m) and courses, required 96 panels of four set to an outside radius of 16 ft (4.88 m). basic shapes, fabricated on pallets All three courses are suspended from 10 x 24 ft (3.05 x 7.31 in). the steel framework (Fig. 7). The spire posed a more complex The spire is composed of six courses problem. Because the spire was tapered all of which are suspended from the vertically in addition to the horizontal steel framework and total 78 ft 3'/a in. curves, the shape of the curve was con- (23.9 m) in height. In addition to the tinually changing. Therefore, it was de- horizontal sculpturing, the spire tapers cided to calculate the curve every 8 in. from an outside radius of 9 ft (2.74 in) at (203 mm) and provide the mold de- the base to 1 ft 3 in. (0.38 m) at the top partment with a full-sized template for (Fig. 8). each curve from which the individual plywood rib was fabricated. This deci- sion, in retrospect, proved to be sound Mold Fabrication and saved many hours of mold fabrica- As with any unique and complicated tion time. The spire contained 44 architectural cladding project, the panels of seven basic shapes.
36 TOWER SECTION (A) ELEVATION OF TOWER
Fig. 5. Elevation of tower and first tier section. TOWER SECTION 0
CONCREI CURB
ELEVATION OF 2ND TIER OF TOWER
Fig. 6. Second tier of tower.
38 TOWER SECTION cQ
WINDOW HEAD
ELEVATION OF 3RD TiER OF TOWER
Fig. 7. Third tier of tower.
PCi JOURNAL September-October 1982 39 1Po "^
ts i/i N
Z O
OFRC SPIRE IS SUPPORTED AND ANCNORED BY OUTRIGGERS FROM STEEL FRAMEWORK Fig. 8. Elevation of spire.
One mold required special treatment. tive scale model in order to observe vis- The largest section of the lowest spire ually, the appearance of the mold. The course became a warped surface at the mold was then molded with plaster location of its intersection with the using the loft-template method and fi- tower windows, and that portion of the berglass coated. panel could not be determined In total, the tower spire contained mathematically. Therefore, a positive 212 panels from 55 basic shapes re- plaster model 1116 of full size was made quiring 26 separate molds. The mold to ensure proper proportions of the fabrication required 3830 man-hours warped surface. while the warped surface mold re- A cast was then made from the posi- quired 480 man-hours of that total.
40 y ^r.
Fig. 9. The sculptured mold work was an intricate operation requiring extreme care and skill.
Casting The casting procedure was relatively i simple, but the execution of that proce- dure required considerable patience, ingenuity, and ability. The forms were coated with a chemical surface retarder. The '/a in. (13 mm) thick facing mix was applied; however, the deep curves pro- vided some nearly vertical and reverse draft surfaces. These conditions precluded the use of normal concrete placing procedures. Rather, the cement rich "sticky" mix of 1/4 in. (6.3 mm) aggregate had to be hand troweled on the surface and con- solidated by "tapping" using a rigid nylon bristle brush. Timing of con soli- ; dation was critical to prevent either sloughing or segregation. While the ,. facing mix was still in a wet state, the 3 in. (10 mm) thick GFRC skin backup in Fig. 10. The sculptured molds were addition to the required stiffening ribs plywood ribbed with the plywood skin were hand sprayed-up (Fig. 11). molded to the rib shape and then The panels were stripped, then fiberglass coated.
PCI JOURNAL15eptember-October 1982 41 Fig. 11. Casting operation showing spray-up of GFRC skin backup.
Fig, 12. The two surfaces of the panel were tied together mechanically and then glued together with GFRC.
42 Fig. 13. Crane and steel framework used to erect tower spire panels. moist-cured. The retarded surface was proximity of the jobsite, transportation lightly water-blasted with sand to ex- was not a problem. pose the aggregate; thus, very little Erection was accomplished with the grouting was required. use of a Link-Belt Model 238 125-ton Once under full production, two crane. four-man crews were employed to pro- The location of the tower spire re- duce, strip, and finish the panels, Each quired 200 ft (61 m) of boom and 60 ft crew averaged two panels per day. (18.3 m) of jib for a total of 260 ft (79.2 As with the mold fabrication, the m) of "stick" (see Figs. 13, 14, and 15). warped surface panel required particu- Due to the advanced stage of con- lar attention. The panel was such that struction, access for the crane was lim- the two surfaces that constituted the ited to one side of the building, further panel were approximately 90 deg to one restricting the mobility of the crane. another. As a result, one surface was These restrictions limited the theoreti- initially cast, the mold rotated, then the cal capacity of the crane to 4000 lb other surface cast against the first. The (1814 kg). The design weight of the two surfaces were tied together me- largest panel being handled was 3900 chanically then "glued" together with lb (1769 kg) although the actual weight CFRC (see Fig. 12). of the panel turned out to be 4050 lb (1837 kg). The panel handled and erected as anticipated. Erection During erection, the operator could The panels were odd-shaped and not view the product being placed; ac- awkward to transport, but due to the tual placing was accomplished by re-
PCI JOURNAL.'September-October 1982 43 layed hand signals and radio communi- cation. Handling of the panels was by the use of coil bolts threaded into inserts in the panels. The coil thread inserts were cast into a lightweight aggregate block, then the block-insert encapsulated within the panel GFRC ribs (Fig. 16). The use of the insert-block concept was developed on previous GFRC jobs when some production difficulties were encountered while attempting to cast the required inserts in GFRC with proper consolidation around the insert, i.e., maintain dimensional integrity of the insert without interruption of the normal spray-up operation. The insert block eliminated these production irri- tations. On the first and second tier levels, concrete curbs were cast matching the exterior configuration of the tower. Full-sized plywood templates were Fig. 14. Erection of tower spire panel. furnished to the general contractor for
Fig. 15. Closeup of tower spire panel during erection.
44 GFRC TOWER TIER
L-
INSERT BLOCK
3 sit
;URB Fig. 16. Detail of insert block encapsulated within GFRC panel ribs. that purpose. The curbs provided the Due to the complexity of the spire bearing for the panels, with angles pieces, the spire was shop assembled bolted to the insert block and then and match marked to ensure proper fit welded to cast-in plates in the curb. A (see Fig. 19). The steel fabricator also similar tie-back connection was pro- had prefit and match-marked the steel. vided at the top of the panels (Fig. 16). Yet, in spite of this prework, erection of The four-man erection crew placed the spire was tedious and slow. these two tiers in 15 working days for The steel framework and the limited an average of about five panels per day. space available to work became major Bearing for the panels on the third obstacles. The inclined final position of tower tier and all of the spire was pro- the panels, the limited distance be- vided by steel rings or outriggers from tween supporting outriggers, and other the structural steel framework. Tie-back factors that were irritants on the tower connections to the steel are of the pre- now became major problems. As a re- viousl y described insert block and sult, erection of the 44 pieces on the angle type (see Figs. 17 and 18). The spire required 20 working days, or less steel framework congested the working than three pieces per day. area and did prove troublesome. The 96 The most exasperating factor during pieces for this tier were erected in 15 the erection was related to the boom working days or an average of six length. Air movement of any velocity panels per day. moved the product as if in a typhoon
PCI JOURNAL/September-October 1982 45 CONCLUDING REMARKS rIER z 4 . ; 1^8 The Jordan River Temple is a dra- matic demonstration of the fact that
IL OUTRIGGER GFRC should be considered as a prod- uct that will permit the precast concrete 3 SIDES industry to compete in areas where conventional precast concrete is not al- 9 x4 "A 1/2" ways applicable. It was particularly satisfying that at Jordan River, we were able, through T BLOCK the use of GFEC, to offer the architect a material which would permit a "same- Fig. 17. Detail of tie-back connection of ness" throughout the entire building. I insert block. am confident that had GFRC been available at the time, the glass fiber reinforced plastic spires on previous temples would have been made of and was the major cause of down days. GFRC. Eventually, however, all the above Finally, it should be borne in mind problems were solved and the project that GFRC is a labor intensive product was completed successfully. manufactured from relatively expensive The Jordan River Temple was dedi- raw materials. As such, GFRC should cated on November 9, 1981 (Fig. 20). not be considered a panacea or cheap The cost of the tower spire GFRC building material. The cost of the panels was about $658,000, or $33.88 GFRC panels at Jordan River was con- per sq ft ($3651m2). siderably higher than other GFRC praj-
Fig. 18. Insert block mechanically fastened.
46 ects because the ratio of panels to molds required was extremely low, the number of panels produced daily was small, and the number of panels erected daily was extremely low. Obviously, the total in-place cost of GFRC is dependent on many factors, and while the savings derived from the use of GFRC are corollary, they could be considerable.
Credits Owner: Church of Jesus Christ of Latter-Day Saints, Salt Lake City, Utah. Architect: Emil B. Fetzer, LDS Church Temple Architectural Department, Salt Lake City, Utah. Engineer: LDS Church Temple En- gineering Department, Salt Lake City, Utah. Contractor: Layton Construction, Salt Fig. 19. Spire was shop assembled and Lake City, Utah. match marked to ensure proper fit. This Precaster: Buehner Concrete Co., Salt operation required much care, time and Lake City, Utah. skill to execute.
Fig. 20. Finished view of Jordan River Temple.
PCI JOURNAL/September-October 1982 47