Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Package No.NWPCP-7 Item No 1 Title : Detail Structural Design Calculation for Powerhouse -2 Date Prepared by 24-Sep-22 YS Output/Remarks The construction of Powerhouse 1 (PH1), located beside Wemedilla Reservoir, is proposed to carry out under the Northern Western Province Canal Project - Package 7. This report consists of the detail structural design of the buried penstock pie conducted in conjunction with Eurocode. The Penstock about 130m long with 0.5% and 44.5% gradient are proposed. CS# Road Finish Level (MSL) 0 1 2 3 239.65 240.4 239.7 231.9 Pipe Top Overburden Height (m) (MSL) 234.45 234.34 234.16 226.83 5.2 6.06 5.54 5.07 Figure - Coss Sectional View of the PH1 - penstock Conservatively 7m overburdern is considered with provision for acciedential filling over exisiting ground Page 1 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Figure 2 - Transverse Elevational view of the PH1 - Penstock Design Working Life The Design working life is interpreted as the period for which a structure or part of it is to be used for its intended purpose with anticipated maintenance but without major repair being necessary. This is designed for 100 years working life Design working life category 5 Indicative design working life ( years) 100 Examples Civil engineering structures Page 2 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No Date STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Prepared by 24-Sep-22 YS Output/Remarks Material Table 12 : Annex A: Design Manual PMDSC cl 3.5.2 Specificat ions cl 3.3.2, Specificat ions Concrete Concrete Class for Structure = C20/25 Characteristic Cylinder Strength of the Concrete = Characteristic Cube Strength of the Concrete = 20 25 2 N/mm 2 N/mm Steel Characteristic yield strength = 2 N/mm 500 class B , High Bond Steel Exposure Class In conjunction with Eurocode guidelines the exposure class for this structure is takes as XC4 Exposure Class Conjuction with Table 4.1 EC1 Stating Strctural Class Design Working life 100 yrs Strength Classs Meember of Slab Geometry special Quality control allowed Modified Structural Class XC4 S4 2 0 0 0 S6 Minimum Cover Cmin,dur Cdev Nominnal Cover Cnom 40 mm 10 mm 50 mm Page 3 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Design Specifications The structure is designed in conjuction with BS EN 1992 -1-1 2004 : Eurocode 2, which is Eurocode standard for design of concrete structures. Additionally below standards are used ,explicitly , in this design. BS EN 1990 : Basis of Structural Design In addition following design specifications are used. 1. Hydraulic Structures Design Manual, April 2018- MWSIP 2. BS EN 1991-1-1 Eurocode 1 : Action on Structures - Densities, self wight and Imposed Loads 3. BS EN 1997 Eurocode 7 : Geotechnical Design 4.Contract Agreement. Volume II - Employer's Requirement - Section 6 & Specifications Soil Parameters Soil parameters are selected as per the Design Manual of the MWSIP Reference is made to Table 2 of the Design Manual For the foundation design, the soil investigation carried out by PMDSC is incorporated. The reference Borehole # - BWBH 06 Page 4 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks 2.0 Design Criteria The structural model is the idealisation of the structural system used for the purpose of analysis, design and verification. The structural model for this assignment is made of, state-of-the-art structural software MIDAS CIVIL. The structural effects such as flexure, shear, deflection, stresses shall be obtained from the analysis at critical sections of the structure. Figure : FE model using MIDAS CIVIL Page 5 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Soil Structure Interaction The stiffnesses of the soil and structure are comparable and therefore soil structure interaction is taken in to account. This is done using spring analogy and incorporating Soil Subgrade Modulus. Foundation is modeled using discrete uncoupled springs. ks = 40 (SF) qa = 40 x 3x150 ks = 18000 kN/m3 kN/m3 The Boundary Conditions of the Structure The boundry condition of the structure is defined by the soil structure interaction owing to foundation rest on the soil/ highly weather rock and modereatly weather rock. This is simulated by spring in the Finite Element Model Figure : Point Spring assigned to the foundation Page 6 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Lateral Earth Pressure Φ ka ko 30 (1-sin Φ)/(1+sin Φ) 0.333 (1-sin Φ) 0.5 reference is made to item 2.3 of Design Manual (MWSIP) Page 7 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No Date STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Prepared by 24-Sep-22 YS Output/Remarks Earth Pressure Due to Earthquake The active earth pressure (combined static and dynamic forces) is accounted as below K AE cos 1 cos cos cos Z where 2 2 Z 2 sin sin cos cos kh = 0.1 kh = 0.18 is selected for dam structure K AE cos cos 2 1 2 sin sin 2 cos 30 5.71 cos 2 0.83099 2 sin sin 0.4544 Φ Ψ cos cos 2 1 degrees degrees sin sin cos kAE 2 0.95621 0.9 Page 8 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Sign Convention for Resut Interpretation Figure : Sign Convention Page 9 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Page 10 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Prepared by 24-Sep-22 YS Output/Remarks 0.1 kh = K AE cos 2 cos 1 2 sin sin 2 cos 30 5.71 cos 2 0.83099 2 sin sin 0.4544 Φ Ψ Date cos cos 2 1 degrees degrees sin sin cos 2 0.95621 kAE 0.9 PAE 1 K AE (1 k v )h 2 2 @ 6.5 depth PAE @ 8.8 m depth PAE Equalant latteral static Force 359.8 659.5 299.7 kN/m kN/m kN/m Construction Surcharge During the construction , the maximum construction machinery Pa = kaq 0.00 kN/m2 Lateral 7.7 kN/m Page 11 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Vehicular Load 13.1 kN/m2 Page 12 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Page 13 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks 4. Finite Element Model Page 14 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Result Output Figure : ULS Hoop Forces Figure : ULS Bending Moment Envelop Page 15 of 27 Mahaweli Water Security Investment Program (MWSIP) Project : MWSIP Package No.NWPCP-7 Item No STRUCTURAL DESIGN OF POWER HOUSE 2 (PH2) Date Prepared by 24-Sep-22 YS Output/Remarks Figure : ULS Shear Force kN/m Page 16 of 27
