STRUCTURAL BASIS OF DESIGN
Engineers Without borders
Agua Caliente Dam
Guatemala
Scope of Work:
Location:
The Dam is located near Agua Caliente
Latitude: 14.811194
Longitude: -90.8542
Country: Guatemala
Preliminary Drawings:
Governing Codes, Standards, and Publications:


American Concrete Institute (ACI)
o
ACI 318 Building Code Requirements for Structural Concrete
o
ACI 350 Code Requirements for Environmental Engineering Concrete Structures
o
ACI 301 Standard Specification for Structural Concrete
American Society of Civil Engineers (ASCE)
o ASCE 7-05 Minimum Design Loads for Buildings and Other Structures

Corps of Engineers Engineering Manuals
o EM 1110-2-1603 - Hydraulic Design of Spillways
o EM 1110-2-2000 - Standard Practice for Concrete for Civil Work Structures
o EM 1110-2-2100 - Stability Analysis of Concrete Structures
o EM 1110-2-2104 - Strength Design of Reinforced Concrete Hydraulic
Structures
o EM 1110-2-2200 - Gravity Dam Design
Loadings Requirements:
Design loads are based on ASCE 7-05 Minimum Design Loads for Buildings and Other
Structures.
Hydrostatic Load: The hydraulic Load will be calculated assuming the dam is a retaining wall,
with water height equal to the dam height (worst condition).
Unit Weight Water, γw = 62.4 pcf
Lateral Pressure – 1ft section
Pw = ½hdγw = 530 psf
Description
Elevation (ft.)
Post-Construction
Existing Condition
Condition
Normal Reservoir Pool
PMF Peak Reservoir Elevation
Wet Season Drawdown Minimum Elevation
Spillway Crest / Sill
Reservoir Bottom Immediately Upstream of
Spillway
Top of Dam (hd)
U/S Silt El.
D/S Apron Slab El.
Earth Load: The hydraulic
Angle of internal friction, φ = 40.03°
Unit Weight Soil, γe = 80.1pcf
Unit Weight Water, γw = 62.4 pcf
Active earth coefficient
Ka = tan2(45° - φ/2) = 0.2171
17
11
17
11
Total Load – 1ft section
Ha = ½Kaγehe2 = 1052 psf
True Load – 1ft section
Ha’ = Ha – Pw’ = ½Kaγehe2 - ½heγw = 709 psf
Dead Loads: Selfweight of the structure will be used.
Unit Weight Concrete, γc = 150 pcf
Dam Dead Load, 1ft section = hdγc = 2250psf
Live Loads: In accordance with ASCE 7-05 Table 4-1
Pedestrians (one or two on foot) = 20 psf (similar to a roof)
Wind Loads: In accordance with ASCE 7-05 Chapter 6
Downstream Face = 20psf
Much smaller than the opposing hydrostatic force
Seismic Loads: Seismic loads will be calculated in accordance with ASCE 7-05 based on
following coefficients using the simplified method.
Mapped spectral accelerations based on _____________________
Latitude: 14.811194
Longitude: -90.8542
Short Period, Ss = 1.592g
1-second Period, S1 = 0.4908g
Site Class, D
Site Coefficents:
(ASCE 7-05 Table 20.3.1)
Fa = 1.0
Fv = 1.5
Maximum considered earthquake
(ASCE 7-05 Table 11.4.1)
(ASCE 7-05 Table 11.4.2)
Spectral response acclerations:
(ASCE 7-05 Table 11.4.3)
Short Period SMS = FaSs = 1.592g
1-second Period SM1 = FvS1 = 0.7362g
Design spectral response acclerations:
(ASCE 7-05 Table 11.4.4)
Short Period SDS = 2/3 SMS = 1.0613g
1-second Period SD1 = 2/3 SM1 = 0.4908g
Seismic Performance Category,
(ASCE 7-05 Table 11.6)
Short Period, D
1-second Period, D
Occupancy Category, 1
(ASCE 7-05 Table 1.1)
Importance Factor, I = 1
(ASCE 7-05 Table 11.5-1)
Material Design Specifications and Design Criteria:
Cast-in-place Concrete:
Buildings Foundations, wall, Slab: fc’ = 4000psi w/c ration = 0.5
Reinforcing Steel: ASTM A615, Grade 60
Serviceability: The deflection of all structural, reinforced concrete and steel members will be
subject to the requirement of ACI 318/350, and AISC – 360-05 respectively
Load Combinations:
Case 1 – Usual Loading Combination: Normal Operating Condition, Normal Pool +
Normal Tailwater + Silt
Case 2 – Unusual Loading Combination: Flood Discharge Loading, Maximum Pool
(Dam overtopping elevation) + Maximum Pool Tailwater + Silt
Case 3 – Unusual Loading Combination: Construction Condition, Backfill Loading
Case 4 – Unusual Loading Combination: Construction Condition & Flood, Backfill
Loading + Maximum Pool (Dam overtopping elevation) + Maximum Pool Tailwater
Based on EM1110-2-2104 “Structural Design for Reinforced-Concrete Hydraulic Structures,”
the following load combinations are assumed for the concrete design. Load combinations are
increased by the hydraulic factor Hf = 1.3 except for members in direct tension.
Factored Load Combinations are listed below where:
D: Dead Loads
L: Live Loads
F: Hydrostatic Load
H: Earth Load
LOAD COMBINATION #1 - 1.3(1.4D+1.7L) = 4139 psf
LOAD COMBINATION #2 - 1.3(1.4D+1.7L+1.7F) = 5311psf
LOAD COMBINATION #3 - 1.3(1.4D+1.7L+1.7H) = 5706 psf
LOAD COMBINATION #4 - 1.3(1.4D+1.7L+1.7F+1.7H) = 6878 psf
Geotechnical Information: