APRIL Conquering the FE & PE exams Formulas, Examples & Applications. Topics covered in this month s column:

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1 APRIL 2015 DR. Z s CORNER Conquering the FE & PE exams Formulas, Examples & Applications Topics covered in this month s column: PE Exam Specifications (Geotechnical) Transportation (Horizontal Curves) Structural Design (LRFD, Steel Design, Columns, Compression Members and Tension Members) Structural Analsis (LRFD, Factored Loads & Moments) Structural Design (LRFD, Reinforced Concrete Beams) Statics and Mechanics of Materials Math (First Order Ordinar Differential Equations) Technolog Usage (Calculator, Casio 115 ES PLUS) Regression Analsis (Calculator, Casio 115 ES PLUS) Converting Binar and Decimal Numbers Triangular Area Computations Using Determinants

2 PE Civil Geotechnical Afternoon Depth Exam Specifications Beginning and effective April 2015 examinations Site Characterization: 5 questions, Soil Mechanics, Laborator Testing, and Analsis: 5 questions, Field Materials Testing, Methods, and Safet: 3 questions, Earthquake Engineering and Dnamic Loads: 2 questions, Earth Structures: 4 questions, Groundwater and Seepage: 3 questions, Problematic Soil and Rock Conditions: 3 questions, Earth Retaining Structures (ASD or LRFD): 5 questions, Shallow Foundations (ASD or LRFD): 5 questions, Deep Foundations (ASD or LRFD): 5 questions,

3 TYPES OF HORIZONTAL CURVES P.C. BC Back Tangent LC T L M E PI I T Forward Tangent NCEES-REF HANDBOOK PAGE-166 R I R P.T. EC Degree of Curve is not shown I = Intersection angle (also called D) D = Degree of Curve (Arc Definition) PI = Point of Intersection PC = Point of Curvature, also called (BC) PT = Point of Tangenc, also called (EC) L = Length of Curve (from PC to PT) T = Tangent Distance E = External Distance R = Radius LC = Length of Chord M = Length of Middle Ordinate HC-111 (1) Simple Curve The simple curve is an arc of circle. The radius (R) determines the sharpness or flatness of the curve. (2) Compound Curve The compund curve consists of two simple curves joined together curving in the same direction. (3) Reverse Curve A reverse curve consists of two simple curves joined together, but curving in opposite direction. For safet reasons the use of this curve should be avoided. (4) Spiral Curve The spiral curve is a curve that has a varing radius. It is used on most modern highwas and railroads. It is used for transition from the tangent to a simple curve or between simple curves.

HORIZONTAL (CIRCULAR) CURVES IMPORTANT FORMULAS 5729.

4 HORIZONTAL (CIRCULAR) CURVES IMPORTANT FORMULAS R D R LC 2sin( I / 2) T R tan ( I / 2) LC T 2cos( I / 2) L RI 180 I D 100 M R[1 cos ( I/ 2)] HC 555

5 TRANSPORTATION HORIZONTAL CURVE DESIGN T =? PI I = 15 o T =? PC R =? I R =? PT D = 3 o I = 15 o sta PI = A 3 o 30 horizontal curve has forward and backward tangents that intersect at station Knowing that the intersection angle is I = 15 o 34 20, determine the following: (a) the radius of the curve (R) (b) the tangent distance ( T ) (c) the length of long chord ( LC ) (d) the external distance ( E ) (e) the length of middle ordinate ( M ) (f) the length of curve ( L ) (g) the station of PC, sta (PC ) (h) the station of PT, sta (PT ) NCEES REFERENCE HANDBOOK PAGE-166 Answers: a) the radius of curve : R = ft. (b) the tangent distance : T = ft. (c) the length of long chord : LC = ft. (d) the external distance : E = ft. (e) the length of middle ordinate : M = ft. (f) the length of curve : L = ft. (g) the station of PC : sta (PC) : (h) the station of PT : sta (PT) : HC-76

6 TRANSPORTATION HORIZONTAL CURVES PC PI PT Sta PI = R R I = 12 o D = 5 o I = Intersection Angle A 5 o horizontal curve has forward and back tangents that intersect at station Knowing that the intersection angle is I = 12 o 24 36, answer the following questions: (1) the radius (ft) of the curve is most nearl, R (A) (B) (C) (D) (2) the tangent distance (ft) of the curve is most nearl, T (A) (B) (C) (D) (3) the station of point of curve - PC is most nearl, PC (A) (B) (C) (D) (4) the station of point of tangent - PT is most nearl, PT (A) (B) (C) (D) HC-90 Important note for students: This problem is for practice and has four questions. In real FE & PE exams, each problem will have ONLY ONE question.

7 TRANSPORTATION HORIZONTAL CURVES PC R PI R PT Sta PI = I = 26 o 24 E = 62.2 ft I = Intersection Angle Two segments of a transportation route intersect at station with a deflection angle of 26 o 24. If the external distance E from the PI to the centerline of the highwa is measured as 62.2 ft, determine the following: (1) the radius (ft) of the curve is most nearl, R (A) (B) (C) (D) (2) the degree of the curve (deg-min) is most nearl, D (A) (B) (C) (D) 4 deg 40 min 3 deg 30 min 3 deg 18 min 2 deg 30 min (3) the tangent distance (ft) of the curve is most nearl, T (A) (B) (C) (D) (4) the station of point of curvature-pc is most nearl, PC (A) (B) (C) (D) HC-113

8 TRANSPORTATION HORIZONTAL CURVES PC PI I = 35 o 24 PT R = 400 m R = 400 m I = 35 o 24 I = Intersection Angle O A horizontal curve is given as shown above. The intersection angle and the radius of the curve are given as listed. The shaded area (m 2 ) between the circular curve and the tangents is most nearl: (A) 4,879 (B) 3,577 (C) 2,427 (D) 1,635 HC-74

9 Problem: ( Transportation / Horizontal Curves ) R = 2,600 ft PT =? I = 68 o PC = R = 2,600 ft PC = PI =? 68 o I = Intersection Angle Referring to the horizontal curve shown in the figure above, answer the following questions: (1) the tangent distance (ft) of the curve is most nearl, T (A) (B) (C) (D) (2) the external distance (ft) of the curve is most nearl, E (A) (B) (C) (D) (3) the station of point of intersection-pi is most nearl, PI (A) (B) (C) (D) (4) the station of point of tangenc-pt is most nearl, PT (A) (B) (C) (D) HCMC-242 Important note for students: This problem is for practice and has four questions. In real FE & PE exams, ever problem will have ONLY ONE question.

10 COMPRESSION MEMBERS COLUMN FORMULAS P u P c n P P A F u c n c g cr P u = Total Factored Loads P n = Nominal Compressive Strength c P n = Design Compressive Strength F cr = Critical Buckling Stress A g = Gross Area of the Cross-Section φ c = Resistance Factor (for columns φ c = 0.90) Fe 2E ( KL/ r) 2 F e = Euler s Stress (elastic buckling stress) K = Effective Length Factor L = Column Length KL = Effective Column Length r = Radius of Gration (alwas min. value) STEEL 100 SPRING 2015

11 IMPORTANT STEEL COLUMN FORMULAS P u P c n Fe P F A c n c cr 2E ( KL/ r) 2 g 0.90 c Resistance Factor KL 4.71 E F r F cr F F e F KL E 4.71 r F F cr F e K = Effective Length Factor (AISC) L = Column Length KL = Effective Column Length KL / r min = slenderness ratio r min = minimum radius of gration F = Yield Stress of Steel (ksi) F e = Euler stress or Elastic Buckling Stress (ksi) F cr = Critical Stress (ksi) E x = Modulus of Elasticit of Steel STEEL 111 SPRING 2015

12 AISC TABLES / CHARTS FOR COMPRESSION MEMBERS EFFECTIVE LENGTH FACTORS ( K ) NCEES Reference Handbook, page-158 (Adapted from AISC, Steel manual, 2011) KL 4.71 E F r F cr F F e F AISC E 3 2 KL E 4.71 r F F cr F e AISC E 3 3 STEEL 444 SPRING 2015

13 Problem: (Design Strength) W 10 x 33 ASTM-A992 Steel Both Ends Pinned E = 29 x 10 3 ksi COLUMN W 10 x 33 L = 15 ft (a) Find the slenderness ratio (KL / r) (b) Find the Euler Stress (F e ) (c) Find the critical buckling stress (F cr ) (d) Find the nominal compressive strength (P n ) (e) Find the design compressive strength (f c P n ) Solution: W 10 x 33 Steel / A992 F = 50 ksi F u = 65 ksi A g = 9.71 in 2 r x = 4.19 in. r = 1.94 in. r min = 1.94 in. The Slenderness Ratio: ( KL / r ) Here K = 1.0, NCEES-Ref. Book / Page 158 KL / r min = 1.0 x (15 x 12) / 1.94 = < 200 O.K. The Criteria for the Critical Buckling Stress Equation: ( F cr ) 4.71 E 29,000 = 4.71 = F ( KL / r min ) = < 113.4, Use AISC Equation E 3.2 The Euler Stress (F e ) p 2 (29,000) (92.78) 2 F p 2 E e = = ( KL / r min ) 2 = ksi STRESS RATIO: F / F e = 50 / = The Critical Buckling Stress: ( F cr ) F / F e F cr = (0.658 ). F = (0.658) (1.504) (50) = ksi (AISC Equation E 3.2) The Nominal Compressive Strength: (P n ) P n = F cr. A g F cr = (26.65) (9.71) = kips The Design Compressive Strength: (f P c n ) f P c n = 0.90 x = kips f P c n = kips CY-330

14 DESIGN OF STEEL STRUCTURES COMPRESSION MEMBERS Problem: Steel Column (W) Pin Weld Channel COLUMN Two C 15 x 50 L = 24 ft Pin Two C 15 x 50 Two C-Channels are welded together at flanges Two C 15 x 50 channels are welded together to form a column as shown in the figure. Using the data for the cross section and the column length, answer the following questions: (1) The min. area moment of inertia (in 4 ) is most nearl: (A) (B) (C) (D) I min =? (2) The minimum radius of gration (in.) is most nearl: (A) 4.60 (B) 4.08 (C) 3.60 (D) 3.05 r min =? (3) The slenderness ratio of the column is most nearl: (A) (B) (C) (D) K L =? r min STEEL-184

15 DESIGN OF STEEL STRUCTURES COMPRESSION MEMBERS Problem: Steel Column (W) Pin 4 in. 4 in. COLUMN Two L 6 x 4 x 5 / 8 LLBB Fixed L = 15 ft 6 in. Two L 6 x 4 x 5/8 LLBB LLBB = Long Legs Back to Back Two L 6 x 4 x 5 / 8 angles are welded together to form a column as shown in the figure. Using the data for the cross section and the column length, answer the following questions: (1) The min. area moment of inertia (in 4 ) is most nearl: (A) (B) (C) (D) I min =? (2) The minimum radius of gration (in.) is most nearl: (A) 4.20 (B) 3.18 (C) 2.45 (D) 1.53 r min =? (3) The slenderness ratio of the column is most nearl: (A) (B) (C) (D) K L =? r min STEEL-182

16 DESIGN OF STEEL STRUCTURES COMPRESSION MEMBERS Problem: Steel Column (W) Fixed COLUMN W 14 x 61 Fixed L = 20 ft W 14 x 61 ASTM-A992 E = 29 x 10 3 ksi Top end fixed Bottom end fixed The W 14 x 61 steel column is 20 ft. long and supported as shown. Using the listed data answer the following questions: (1) The slenderness ratio of the column is most nearl: (A) (B) (C) (D) K L =? r min (2) The design strength of the column (kips) is most nearl: (A) 686 (B) 599 (C) 495 (D) 425 f P n =? STEEL-174

17 DESIGN OF STEEL STRUCTURES COMPRESSION MEMBERS Problem: Steel Column (W) Pin COLUMN 2 W 12 x 40 Pin L = 30 ft x x 2 W 12 x 40 Two W-shapes are welded together at flanges Two W 12 x 40 shapes are welded together to form a column as shown in the figure. Using the data for the cross section and the column length, answer the following questions: (1) The min. area moment of inertia (in 4 ) is most nearl: (A) (B) (C) (D) I min =? (2) The minimum radius of gration (in.) is most nearl: (A) 3.20 (B) 3.88 (C) 4.45 (D) 4.86 r min =? (3) The slenderness ratio of the column is most nearl: (A) (B) (C) (D) K L =? r min STEEL-186

18 STEEL DESIGN / LRFD TENSION MEMBERS / DESIGN STRENGTH Problem: L 4 x 4 x 7/ in. 2.5 in. 2.5 in. Angle STEEL A36 2 in. 3/4 DIAM BOLTS L 4 x 4 x 7/16 A L 4 x 4x 7/16 tension member is connected with 3/4-in. diam. bolts as shown in the figure. If A36 steel is used and both legs of the angle are connected, answer the following questions: (1) The effective net area (in. 2 ) of the member is most nearl (A) 2.15 (B) 2.30 (C) 2.64 (D) 3.85 A e =? (2) The tensile design strength (kips) of the member is most nearl (A) (B) (C) (D) f P n =? STL-140

19 Problem: L 4 x 4 x 7/ in. 2.5 in. 2.5 in. Angle Bolts 3/4 in. diam. A36 Steel 2 in. L 4 x 4 x 7/16 A L 4 x 4x 7/16 tension member is connected with 3/4-in. diam. bolts as shown in the figure. If A36 steel is used and both legs of the angle are connected, determine the design strength. Solution: Angle L 4 x 4 x 7/16 L 4 x 4 x 7/16 A = A gross = 3.31 in 2. (from manual ) A36 F = 36 ksi, F u = 58 ksi t w = 7/16-in. L 4 x 4 x 7/16 Unfold both legs of the angle and find the gage distance (g ) L 4 x 4 x 7/16 ANGLE PLATE 2.5 in. 2.5 in. 2 in. Effective net area: (A e ) g = Gage Distance g = /16 = in. Hole diameter: d hole = d bolt + 1/8 = 3/4 + 1/8 = 7/8-in. A net = A gross - d.t - d.t = /8 (7/16) - 7/16 [ 7/8-2 2 /(4x4.563) ] = 2.64 in. 2 Since the both legs of the angle are connected: A n = A e A eff = A net = 2.64 in. 2 The design strength based on ielding or gross area: (f t Pn) f t P n = 0.90 F A gross = 0.90 (36) (3.31) = kips = 107 kips The design strength based on fracture or effective area: (f t Pn) f t P n = 0.75 F u A eff. = 0.75 (58) (2.64) = kips The design strength is the smaller value. f t P n = 107 kips STL-75

20 STRUCTURES / REINFORCED CONCRETE FACTORED LOADS / MAX. FACTORED MOMENT LL = 25 kips Service Loads A DL =1.90 k/ft B ft L = 35 ft 20 ft g R/C = 150 lb/ft 3 3 Section The beam weight will be included in the computations: A simpl supported R/C beam is loaded as shown. Considering the weight of the concrete beam, the maximum FACTORED bending moment (k-ft) is most nearl: +V +M (A) 520 (B) 593 (C) 686 (D) 793 M u =? max COMPLETE SOLUTION MCBM-325

21 FACTORED LOADS / FACTORED MOMENTS 25 kips Service Loads A 1.90 k/ft B ft L = 35 ft 20 ft Section 3 Factored Loads 40 kips 3.0 k/ft k k Beam Weight BM = 600 lb/ft k Shear Diagram 9.64 k k (V) Beam Weight Maximum Factored Moment k (16)(36) BM = (150) = 600 lb/ft = Factored Dead Load w u = 1.2 ( ) = 1.2 (2.5) = 3.0 k/ft Factored Live Load w u = 1.6 (25 kips) = 40 kips M u = 0.5 (15) ( ) = ft-kips M u = ft-kips RC-325

22 DESIGN OF CONCRETE STRUCTURES LRFD-DESIGN MOMENT CAPACITY Problem: FE/PE EXAM f 24 c = 4,000 psi 27 f = 60,000 psi 4 # 9 g = 150 lb/ft3 c 15 3 The dimensions of a R/C beam section is given as shown. Using the listed data answer the following: The design moment capacit fm n is most nearl (A) 220 ft-kips (B) 285 ft-kips (C) 320 ft-kips (D) 390 ft-kips COMPLETE SOLUTION RC-114-Q

23 { REINFORCED CONCRETE BEAMS LRFD-DESIGN MOMENT CAPACITY 4 # f c = 4,000 psi f = 60,000 psi 15 3 Determine the design moment capacit fmn of the R/C beam shown in the figure. Concrete and steel properties are as listed. Solution: The steel percentage ( r ) { r = A s bd = 4.00 (15)(24) = < < OK r = f c = 4,000 psi f = 60,000 psi From Table r min = r max= The depth of the stress block: a = A s f b 0.85 f c = (4.00)(60,000) (0.85)(4000)(15) = 4.71 in. e c = b 1 = 0.85 since f = 4000 psi c c = 5.54 c = a 4.71 = = b in. 4 # d - c = Drawing the Strain Diagram e d - c ( ) t = = c (0.003) (0.003) = e t = e t = > tension controlled The nominal Moment: (Mn) M n = A s f ( d ( a 4.71 = (4.00)(60) ( 24 = in.-k = ft-kip 2 2 ( f M n = (0.9)(432.9) = ft-kip f M n = ft-kip RC-114

24 Problem: (Centroid / Moments of Inertia) 3 r r = C 2 4 x FE/PE EXAM The dimensions of a composite area are given as shown in the figure. Using the listed data answer the following questions: (1) the distance (in.) of the centroid is most nearl (A) 6.8 (B) 7.0 (C) 7.5 (D) 8.0 (2) the moment of inertia ( in. 4 ) about the horizontal centroidal axis is most nearl (I cx ) (A) 725 (B) 793 (C) 826 (D) 952 (3) the moment of inertia ( in. 4 ) about the vertical centroidal axis is most nearl (I c ) (A) 221 (B) 288 (C) 315 (D) 424 Answers 1- (D) 2- (C) 3- (A) Important note for students: This problem is for practice and has four questions. In real FE & PE exams, each problem will have ONLY ONE question. MCC-162

25 Problem: (Cantilever Beams) 20 kn/m 30 kn 50 ft.k FE/PE EXAM A C B 4 m 2 m 2 m Support A : Fixed The cantilever beam is loaded as shown in the figure. Using the given loads and the support condition, answer the following questions: (1) The vertical support reaction (kn) at the fixed support, A (A) 140 (B) 125 (C) 110 (D) 100 (2) The magnitude of the bending moment (kn.m) at the fixed support, M A (A) 290 (B) 390 (C) 465 (D) 520 +M -M (3) The magnitude of the moment (kn.m) at C, the mid-point of AB, is most nearl, M C (A) 515 (B) 420 (C) 338 (D) 210 (4) The shear force (kn) at the mid-point of AB is most nearl (A) 42.5 (B) 50.0 (C) 60.5 (D) 70.0 MCBM-331 SPRNG 2015 Important note for students: This problem is for practice and has four questions. In real FE & PE exams, each problem will have ONLY ONE question.

26 FIRST ORDER LINEAR ORDINARY DIFFERENTIAL EQUATIONS d d t = a b FE EXAM (a) Find the general solution of this ODE (b) Find the particular solution when t = 0 then = o Solution: d d t = a b ln - b/a = a t + C 1 ò d d t d = ( - b/a) d ( - b/a) a( - b/a) = = a d t ò a d t - b/a - b/a - b/a = e = e e = e ( a t + C 1 ) a t a t - b/a = + C 2 e C 1 C 2 a t ln - b/a = a t + C 1 = b/a + C e a t General Solution C: Arbitrar constant Because of the arbitrar constant C we have infinitel man solutions. Particular solution is also called the Initial Value Problem: t = 0 = o } C = o b a = b/a + ( o b a ) a t e Particular Solution MATH-640

27 FIRST ORDER LINEAR ORDINARY DIFFERENTIAL EQUATIONS d d x = FE EXAM (a) Find the general solution of this ODE (b) Find the particular solution when x = 0 and = 850 Solution: d d x d d x = d = d x 2 d d x ò d = = d ( ) = d x = ò d x 2 ln = 2 x x = e x 2 + C 1 = e e C = e 2 = 900 = e 2 x + + C 2 C + e 2 x C 1 C 2 C: Arbitrar constant x General Solution Because of the arbitrar constant C there will be infinitel man solutions Integral Curves Particular solution is also called Initial Value Problem: x = 0 = 850 } C = 50 0 x x = e 2 Particular Solution MATH-650

28 FIRST ORDER LINEAR ORDINARY DIFFERENTIAL EQUATIONS (1 ) d d x = 50 FE EXAM The general solution of this First Order Linear Ordinar Differential Equation (ODE) is most nearl: (A) (B) (C) (D) = 200 C 1 = C 1 = x C 1 e = 50 + x e C 1 e 2 x e 2 x C 1 : Integration constant (2 ) d d x = x The general solution of this First Order Linear Ordinar Differential Equation (ODE) is most nearl: (A) = x C 1 e 2 x (B) (C) = x + e x + e = x C 1 C 1 x x e C 1 : Integration constant (D) = 50 + C 1 x e MATH-655

29 LINEAR REGRESSION EQUATIONS Equation of the line: mx b The slope: m n x x i i i i 2 2 i ( i) nx x The -intercept: b i mx n i Correlation Coefficient: R n( x ) x i i i i n( xi ) ( xi) n( i ) ( i) NA 40

30 Problem: The Line of Best Fit x Axis (Title) Line of Best Fit = x R² = x Axis (Title) Slope m = Intercept b = Correlation Coeff. R = SQRT (0.9869) = Excellent Correlation! NA 31

31 CASIO / fx-115 ES PLUS MODE SHIFT SETUP (1) COMP (2) CMPLX (3) STAT (4) BASE-N (5) EQN (6) MATRIX (7) TABLE (8) VECTOR (1) Mth-IO (2) Line-IO (3) Deg (4) Rad (5) Gra (6) Fix (7) Sci (8) Norm FE Exams / Two Number Sstems: 1- Decimal Number Sstem (base 10) 2- Binar Number Sstem (base 2) In Decimal Sstem 10 different digits are used to create an number, and in Binar Sstem onl 0s and 1s are used to create an number. DECIMAL BINARY CASIO 100 SPRNG 2015

32 Binar Number Sstem: NUMBER SYSTEMS BINARY & DECIMAL NCEES Reference Handbook, Page: 213 In digital computers, binar number sstem (the base 2) is used. Conversions from BINARY to DECIMAL or from DECIMAL to BINARY can easil be done using the calculator. Binar (base 2), decimal (base 10). Problem: Find the binar equivalent of decimal 25? 1) Press MODE 2) Press 4 3) Enter 25 and press = 4) Make sure to see 25 under Dec on the screen 5) Press SHIFT then log 6) Answer: Problem: Find the decimal equivalent of binar 1111? 1) Press MODE Turn on our calculator 2) Press 4 3) Press SHIFT then press log ke 4) Enter 1111 and then press = 5) Make sure to see 1111 under Bin on the screen 6) Press SHIFT then hit x 2 ke 7) Answer: 15 Turn on our calculator MATH 126

33 MATH First Press w, then Press 4 for BASE N

34 Step b step Screen Shots: Press 25 and press = ke Press q and then g to get the answer Answer: MATH 126 2

35 Step b step Screen Shots: Press q and then g Enter 1111 Press q then hit d to get the answer Answer: 15 MATH 126 3

36 CONVERTING BINARY NUMBERS TO DECIMALS Convert binar 1011 to decimal: Answer: 11 Convert decimal 18 to binar: (Here keep dividing b base 2) Until the quotient < base MATH 173 DEC BIN Answer: 10010

37 APPLICATIONS OF DETERMINANTS AREAS OF TRIANGLES C Coordinates of vertices: A A ( 8, 10) B (24, 8) C (30, 17) O B x A plane triangle is given as shown in the figure. Using the listed coordinates of the vertices A, B, and C answer the following: The area ( unit 2 ) of this triangle is most nearl: (A) (B) (C) (D) MATH-18

38 AREA COMPUTATIONS Determinants ma be convenientl used in FE exams when the area computations of triangles with coordinates are required. Simplifing complex mathematical expressions would ield a determinant as shown here: Example: A (x 1, 1 ) C (x 3, 3 ) C A B (x 2, 2 ) B O x A triangle ABC is given as shown in the figure. Using the listed coordinates of A, B, and C determine the area of the triangle. Solution: Draw the vertical dashed lines from points A, B, and C. A (x 1, 1 ) C (x 3, 3 ) B (x 2, 2 ) O A C B x Area of the Trapezoid x3 x1 AA CC = ( 1 3) 2 Area of the Trapezoid x2 x3 BB CC = ( 2 3) 2 Area of the Trapezoid x2 x1 AA BB = ( 2 1) 2 Area of ABC = Area AA CC + Area BB CC - Area AA BB This will ield a fairl complex relationship for the area. But if we use determinant relationship, the required area ma be calculated from the following simple determinant. x1 1 Area = ½. x x 1 MTRX 310 SPRNG

39 ABSOLUTE ERROR & RELATIVE ERROR The accurac of a computation is ver important in numerical analsis. There are two was to express the size of the error in a computed result: (a) Absolute Error (b) Relative Error ABSOLUTE ERROR = True Value - Approximate Value Absolute Error RELATIVE ERROR = True Value Example: True Value = 10/3 Approximate Value = (a) Determine the absolute error (b) Determine the relative error (c) Find the significant digits Solution: ABSOLUTE ERROR = True Value - Approximate Value = 10/ = = 1 / 3000 RELATIVE ERROR = = Absolute Error True Value ( 1/3000) (10/3) = 1/10,000 Here, the number of significant digits is 4. MATH-168 FALL 2015

MARCH 2016 DR. Z s CORNER

MARCH 2016 DR. Z s CORNER Conquering the FE & PE exams Problems & Applications Topics covered in this month s column: FE CIVIL Exam Topics & Number of Questions Types of Calculators / FE and PE Exams Technology