(c) Service Bay. --The footings and walls of the substructure below the floor at elevation 5593.50 were designed for the loads of the structure above and to resist the shear and bending moment caused by the varying bearing pressures on the footings and the tensions in the walls from the dowels. The designs of the walls and floor for the substructure with the backfilled cells vented to the tailrace were similar to those described for the control bay. The stability analysis for extreme loading conditions dictated the use of anchors into rock to give stability to this structure. However, during construction the contractor requested and received permission to place concrete that was to be a part of the mass concrete of the outlet works structure as a part of the 13-line wall to elevation 5590.25. The anchors into rock had been installed, but it later appeared they were no longer necessary for the stability of the structure. The floor at elevation 5593.50 was designed for full hydrostatic uplift with maximum tailwater at elevation 5616.9. The intermediate structure consisted of monolithic frames supporting floors and walls at the 11-, 12-, and c-lines. These frames were designed to withstand the loadings from assumed fixed conditions of the superstructure structural steel frames and the contributing floor and wall loadings. Appropriate conditions of loading on walls and slabs were used to determine the maximum moments and shears for the designs of the frames. The a- and 13-line walls were designed to resist the horizontal hydrostatic loads in the expansion and contraction joints separating the walls from adjacent structures. The e-line wall was designed to resist the sponge-rubber pressures caused by the deflection of the dam. The superstructure walls were designed for lateral loads of wind and earthquake by panel coefficients as plates and continuous with or over the supporting structural steel framework. (d) Structure on Dam. --The intermediate structure consisted of monolithic frames along the e- and f-lines and at the 3- through the 9-lines supporting the floors at elevation 5608.50, transformer deck, floors at elevation 5621.00, and superstructures for the lobby and welding and toolrooms. The structure was separated from the dam above elevation 5607.25 by expansion joints shown by details on figure 118 to minimize the effects of the deflection of the dam. The structural frames supporting the transformers were designed for positioning the transformers in a manner that would produce the maximum moments and shears for design of the two-way slabs and frames. A special analysis for the long-term deflection of the transformer deck was completed which indicated that stresses would not be transmitted to the room partitions below. The superstructure framing is a continuation of the intermediate structure framing at the e-line and the 3-, 4-, 11-, 12- and 13-lines with the frames loaded from tributary loads of the slabs and walls. The e-line expansion joint without joint filler was used at the walls and roof slabs of the lobby and welding rooms to prevent transfer of stresses to the powerplant superstructure e-line wall resulting from deflection of the dam and from sidesway. (e) Outlet Gate Structure. --The superstructure concrete, resting on the mass concrete for the dam and the mass concrete for the outlet pipes, was separated by an expansion joint as an extension of the expansion joint of the e-line. Two monolithic frames, one on each side of the expansion joint, were designed to support the walls, the roof; and the loadings from the snatch hook anchors used for installing and removing the ringfollower gates, the hatch, and the expansion coupling. 87. Second-Stage Concrete. This powerplant with a medium-head turbine has the steel draft tube and spiral case completely embedded in second-stage concrete. The draft tube required a hollow, ribbed-steel pier nose filled with concrete to support the concentration of heavy loads of the structure above. After the spiral casing was completely assembled, filled with water and prestressed to the normal operating pressure (160 pounds per square inch), concreting operations were completed. Hoop reinforcement in the concrete around the spiral case was designed to resist the difference between the normal operating pressure and the total pressure under water-hammer conditions. The amount of load transmitted to the concrete was determined by an analysis of a pipe embedded in massive concrete. The mass concrete for the generator foundation was structurally indeterminate because of equipment openings and recesses required and discontinuity effected by the passageways. The bearing and shearing stresses from the generator loads, including synchronous out-of-phase torque, were used in the design of the generator foundation. Each generator stator frame is supported on eight soleplates spaced 45° apart. Four main soleplates support a load of 177, 000 pounds each and four intermediate soleplates support a load of 80,000 pounds. These vertical loads include the hydraulic thrust on the turbine runner. The maximum tangential force for short-circuit torque for each soleplate is 85, 000 pounds. These values are based on manufacturer's data. The estimate of the maximum synchronizing out-of-phase torque is 12, 168, 000 foot-pounds or equal to 159, 000 pounds of tangential force per soleplate. The bearing and shearing stresses on the concrete between the soleplate recesses are well within allowable limits for short-circuit torque. For the severe condition of synchronous out-of-phase torque, the bearing stress reaches 825 pounds per square inch and the shearing stress 95 pounds per square inch. Though high, these stresses are considered permissible since all load is assumed acting on the concrete between the plate recesses. The shearing resistance between the baseplate and concrete also provides an added factor of safety against such high stresses. The lower bearing bracket is supported on four soleplates spaced 90° apart. Each soleplate supports a vertical load of 76, 000 pounds. The tangential force for each soleplate due to braking requirements of the rotating parts of generator and turbine was also investigated. Stresses for both the vertical and tangential loadings were within allowable limits. The second-stage floor slabs at elevations 5607.25 and 5621.00 were designed as twoway slabs fixed on four sides. These slabs were placed later after the shrinkage and temperature change had taken place in the adjacent massive second-stage concrete. 88. Superstructure Structural Steel Design. The superstructure of the powerplant is a structural steel frame with concrete sidewalls and precast concrete panel roof deck. Principal structural members of the superstructure are 11 rigid-frame steel bents (figs. 119 and 120) with built-up steel columns and roof girders, and built-up structural steel crane runway girders for the 150-ton-capacity powerplant crane. The bents are braced by structural steel members placed diagonally between columns and roof girders. Structural steel purlins support the precast concrete panel roof deck, insulation, and five -ply roofing. The rigid-frame members were designed by methods of moment distribution and column analogy. The crane runway girders were designed as continuous over all supports. 89. Nuclear and Chemical, Biological, and Radiological Protection. A national policy as promulgated by the President in May 1958 required the Bureau of Reclamation to provide leadership and example by incorporating radioactive fallout shelters in appropriate new Federal buildings. A preliminary radiological protection survey completed in January 1961 indicated that adequate shelter was available by minor redesign of the powerplant. Supplementary shielding was provided by increasing the thickness of the control room roof and lobby roof, eliminating all exterior windows, and filling the glass panel openings in the wall between the control and generator rooms. Provisions were made for installation of facilities at a later date for decontamination, communication, and power supply. A room was constructed for storage of emergency supplies. Chemical, biological, and radiological operations other than by nuclear explosion were considered. Studies were made to formulate a plan to pressurize the interior of the structure and to add chemical, biological, and radiological (CBR) filters to the ventilation system. A CBR filter system was not installed as it would require modifications to the completed superstructure. Since the commercial availability of an effective CBR filter is questionable, no construction for providing this protection has been undertaken. B. Building Facilities 90. Heating. Heating of the powerplant is provided for the protection of equipment and personnel and for the comfort of the personnel. The heating load for the powerplant |