1. CIVIL ENGINEERING
GEOTECHNICAL Q = KH(Nf /Nd) (for flow nets, Q per unit width),
Definitions where
K = coefficient permeability,
c = cohesion
H = total hydraulic head (potential),
cc = coefficient of curvature or gradation
Nf = number of flow tubes, and
= (D30)2/[(D60)(D10)], where
Nd = number of potential drops.
D10, D30, D60 = particle diameter corresponding to 10%,
30%, and 60% finer on grain-size curve. γ = total unit weight of soil = W/V
cu = uniformity coefficient = D60 /D10 γd = dry unit weight of soil = Ws /V
e = void ratio = Vv /Vs, where = Gγw /(1 + e) = γ /(1 + w), where
Vv = volume of voids, and Gw = Se
Vs = volume of the solids. γs = unit weight of solid = Ws / Vs
K = coefficient of permeability = hydraulic conductivity n = porosity = Vv /V = e/(1 + e)
= Q/(iA) (from Darcy's equation), where τ = general shear strength = c + σtan φ, where
Q = discharge rate φ = angle of internal friction,
i = hydraulic gradient = dH/dx, σ = normal stress = P/A,
H = hydraulic head, P = force, and
A = cross-sectional area. A = area.
qu = unconfined compressive strength = 2c
Ka = coefficient of active earth pressure
w = water content (%) = (Ww /Ws) ×100, where
Ww = weight of water, and = tan2(45 – φ/2)
Ws = weight of solids. Kp = coefficient of passive earth pressure
= tan2(45 + φ/2)
Cc = compression index = ∆e/∆log p Pa = active resultant force = 0.5γH 2Ka, where
= (e1 – e2)/(log p2 – log p1), where H = height of wall.
e1 and e2 = void ratio, and
p1 and p2 = pressure. qult = bearing capacity equation
= cNc + γDf Nq + 0.5γBNγ , where
Dr = relative density (%) Nc, Nq, and Nγ = bearing capacity factors
= [(emax – e)/(emax – emin)] ×100 B = width of strip footing, and
= [(1/γmin – 1/γd) /(1/γmin – 1/γmax)] × 100, where Df = depth of footing below surface.
emax and emin = maximum and minimum void ratio, and
γmax and γmin = maximum and minimum unit dry weight. FS = factor of safety (slope stability)
cL + Wcosα tanφ
= , where
Gs = specific gravity = Ws /(Vsγw), where W sinα
γw = unit weight of water (62.4 lb/ft3 or 1,000 kg/m3). L = length of slip plane,
∆H = settlement = H [Cc /(1 + ei)] log [(pi + ∆p)/pi] α = slope of slip plane,
= H∆e/(1 + ei), where φ = angle of friction, and
H = thickness of soil layer W = total weight of soil above slip plane.
∆e = change in void ratio, and Cv = coefficient of consolidation = TH 2/t, where
p = pressure. T = time factor,
PI = plasticity index = LL – PL, where t = consolidation time.
LL = liquid limit, and Hdr = length of drainage path
PL = plasticity limit. n = number of drainage layers
Cc = compression index for normally consolidated clay
S = degree of saturation (%) = (Vw /Vv) × 100, where
Vw = volume of water, = 0.009 (LL – 10)
Vv = volume of voids. σ′ = effective stress = σ – u, where
σ = normal stress, and
u = pore water pressure.
93
2. CIVIL ENGINEERING (continued)
UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D-2487)
Group
Major Divisions Typical Names Laboratory Classification Criteria
Symbols
D 60
(More than half of coarse fraction is larger than No.
Depending on percentage of fines (fraction smaller than No. 200 sieve size), coarse-grained soils are
Clean gravels (Little or no
cu = greater than 4;
D10
Well-graded gravels, gravel-sand
GW
mixtures, little or no fines
(D ) 2
fines)
cc =
30
between 1 and 3
D 10 × D 60
Determine percentages of sand and gravel from grain-size curve.
4 sieve size)
(More than half of material is larger than No. 200 sieve size)
Gravels
Poorly-graded gravels, gravel-sand
GP Not meeting all gradiation requirements for GW
mixtures, little or no fines
d
Gravels with fines
GMa Above "A" line
amount of fines)
Silty gravels, gravel-sand-silt mixtures Atterberg limits below "A"
(Appreciable
u with PI between 4
line or PI less than 4
and 7 are
classified as follows:
Coarse-grained soils
borderline cases
5 to 12 percent: Borderline cases requiring dual symbolsb
Clayey gravels, gravel-sand-clay requiring use of
GC Atterberg limits above "A"
mixtures dual symbols
line with PI greater than 7
D 60
(More than half of coarse fraction is smaller
Clean sands (Little or no
cu = greater than 6;
More than 12 percent: GM, GC, SM, SC
D10
Well-graded sands, gravelly sands, little
Less than 5 percent: GW, GP, SW, SP
SW
or no fines
(D )2
fines)
than No. 4 sieve size)
cc =
30
between 1 and 3
D 10 × D 60
Sands
Poorly graded sand, gravelly sands, little
SP Not meeting all gradation requirements for SW
or no fines
d Limits plotting in
Atterberg limits below "A"
(Appreciable
SMa Silty sands, sand-silt mixtures hatched zone with
Sands with
amount of
u line or PI less than 4
fines)
PI between 4 and 7
fines
are borderline
Atterberg limits above "A" cases requiring use
SC Clayey sands, sand-clay mixtures
line with PI greater than 7 of dual symbols
Inorganic silts and very fine sands, rock
ML flour, silty or clayey fine sands, or
(Liquid limit less
Silts and clays
clayey silts with slight plasticity
(More than half material is smaller than No. 200 sieve)
than 50)
Inorganic clays of low to medium
CL plasticity, gravelly clays, sandy clays,
silty clays, lean clays
Organic silts and organic silty clays of
OL
low plasticity
Inorganic silts, micaceous or
Fine-grained soils
greater than 50)
MH diatomaceous fine sandy or silty soils,
Silts and clays
(Liquid limit
elastic silts
Inorganic clays of high plasticity, fat
CH
clays
Organic clays of medium to high
OH
plasticity, organic silts
Highly organic
Peat and other highly organic soils
soils
Pt
a
Division of GM and SM groups into subdivisions of d and u are for roads and airfields only. Subdivision is based on
Atterberg limits; suffix d used when LL is 28 or less and the PI is 6 or less; the suffix u used when LL is greater than 28.
b
Borderline classification, used for soils possessing characteristics of two groups, are designated by combinations of group
symbols. For example GW-GC, well-graded gravel-sand mixture with clay binder.
94
7. CIVIL ENGINEERING (continued)
SHORT COLUMNS:
Reinforcement limits: Concentrically-loaded short columns: φPn ≥ Pu
A M1 = M2 = 0
ρ g = st
Ag KL
≤ 22
0.01 ≤ ρg ≤ 0.08 r
Design column strength, spiral columns: φ = 0.70
Definition of a short column: φPn = 0.85φ [ 0.85 fc' ( Ag − Ast ) + Ast fy ]
KL 12 M 1
≤ 34 −
r M2 Design column strength, tied columns: φ = 0.65
where: KL = Lcol clear height of column φPn = 0.80φ [ 0.85 fc' ( Ag − Ast ) + Ast fy ]
[assume K = 1.0]
Short columns with end moments:
r = 0.288h rectangular column, h is side length Mu = M2 or Mu = Pu e
perpendicular to buckling axis ( i.e., Use Load-moment strength interaction diagram to:
side length in the plane of buckling ) 1. Obtain φPn at applied moment Mu
r = 0.25h circular column, h = diameter 2. Obtain φPn at eccentricity e
3. Select As for Pu , Mu
M1 = smaller end moment
M2 = larger end moment
M1
M2
LONG COLUMNS − Braced (non-sway) frames
Definition of a long column: Long columns with end moments:
KL 12 M 1 M1 = smaller end moment
> 34 −
r M2 M2 = larger end moment
M1
Critical load: positive if M1 , M2 produce single curvature
M2
π2 E I π2 E I
Pc = = 0 .4 M 1
( KL ) 2 ( Lcol ) 2 C m = 0.6 + ≥ 0.4
M2
where: EI = 0.25 Ec Ig
Cm M 2
Mc = ≥ M2
Pu
Concentrically-loaded long columns: 1−
0.75 Pc
emin = (0.6 + 0.03h) minimum eccentricity
Use Load-moment strength interaction diagram
M1 = M2 = Pu emin (positive curvature)
to design/analyze column for Pu , Mu
KL
> 22
r
M2
Mc =
Pu
1−
0.75 Pc
Use Load-moment strength interaction diagram
to design/analyze column for Pu , Mu
99
8. CIVIL ENGINEERING (continued)
GRAPH A.11
Column strength interaction diagram for rectangular section with bars on end faces and γ = 0.80 (for instructional use only).
Design of Concrete Structures, 13th Edition (2004), Nilson, Darwin, Dolan
McGraw-Hill ISBN 0-07-248305-9 GRAPH A.11, Page 762
Used by permission
100
9. CIVIL ENGINEERING (continued)
GRAPH A.15
Column strength interaction diagram for circular section γ = 0.80 (for instructional use only).
Design of Concrete Structures, 13th Edition (2004), Nilson, Darwin, Dolan
McGraw-Hill ISBN 0-07-248305-9 GRAPH A.15, Page 766
Used by permission
101
10. CIVIL ENGINEERING (continued)
STEEL STRUCTURES References: AISC LRFD Manual, 3rd Edition
AISC ASD Manual, 9th Edition
LOAD COMBINATIONS (LRFD)
Floor systems: 1.4D Roof systems: 1.2D + 1.6(Lr or S or R) + 0.8W
1.2D + 1.6L 1.2D + 0.5(Lr or S or R) + 1.3W
0.9D ± 1.3W
where: D = dead load due to the weight of the structure and permanent features
L = live load due to occupancy and moveable equipment
L r = roof live load
S = snow load
R = load due to initial rainwater (excluding ponding) or ice
W = wind load
TENSION MEMBERS: flat plates, angles (bolted or welded)
Gross area: Ag = bg t (use tabulated value for angles)
s2
Net area: An = (bg − ΣDh + ) t across critical chain of holes
4g
where: bg = gross width
t = thickness
s = longitudinal center-to-center spacing (pitch) of two consecutive holes
g = transverse center-to-center spacing (gage) between fastener gage lines
Dh = bolt-hole diameter
Effective area (bolted members): Effective area (welded members):
U = 1.0 (flat bars) U = 1.0 (flat bars, L ≥ 2w)
Ae = UAn U = 0.85 (angles with ≥ 3 bolts in line) Ae = UAg U = 0.87 (flat bars, 2w > L ≥ 1.5w)
U = 0.75 (angles with 2 bolts in line) U = 0.75 (flat bars, 1.5w > L ≥ w)
U = 0.85 (angles)
LRFD
Yielding: φTn = φy Ag Fy = 0.9 Ag Fy ASD
Fracture: φTn = φf Ae Fu = 0.75 Ae Fu Yielding: Ta = Ag Ft = Ag (0.6 Fy)
Block shear rupture (bolted tension members): Fracture: Ta = Ae Ft = Ae (0.5 Fu)
Agt =gross tension area
Agv =gross shear area Block shear rupture (bolted tension members):
Ant =net tension area Ta = (0.30 Fu) Anv + (0.5 Fu) Ant
Anv=net shear area
Ant = net tension area
When FuAnt ≥ 0.6 FuAnv:
Anv = net shear area
0.75 [0.6 Fy Agv + Fu Ant]
φRn =
smaller 0.75 [0.6 Fu Anv + Fu Ant]
When FuAnt < 0.6 FuAnv:
0.75 [0.6 Fu Anv + Fy Agt]
φRn =
smaller 0.75 [0.6 Fu Anv + Fu Ant]
0
102