Hi
I have a question, if someone can comment, it woule be greatly appreciated.
I model, analyzed and design a 3 story concrete building using Staad Pro.
The distances in between columns in one direction are 8 - 3 - 7m and in the other are 8 - 7 - 6. It is not simetric.
The loads are for office building.
Most of the columns need the minimun reinforcement which is 15cm2 (all in the first 2 floors).
But in the last floor, some some columns get 32 and 50cm2.
Im well aware that in the last flloor is not strange to get more steel than in lower floors, since you have lower axialforces but bigger
bending.
But, do you thinks that big of a difference is reasonable?
I attach here the staad model.
If someone can comment, will be appreciated.
STAAD SPACE START JOB INFORMATION ENGINEER DATE 12-May-18 JOB NAME Edifico B JOB CLIENT ESCUELA AMERICANA DE TAMPICO JOB NO Analisis 1 Mayo 22 END JOB INFORMATION INPUT WIDTH 79 *----------------------------------------------------------------------------- UNIT METER KG JOINT COORDINATES 1 0 0 0; 2 4.8 0 0; 3 11.07 0 0; 4 17.69 0 0; 5 0 0 7.69; 6 4.8 0 7.69; 7 11.07 0 7.69; 8 17.69 0 7.69; 9 0 0 11.28; 10 4.8 0 11.28; 11 11.07 0 11.28; 12 16.73 0 11.28; 13 0 0 20.02; 14 4.8 0 20.02; 15 11.07 0 20.02; 16 16.73 0 20.02; 17 0 5.4 0; 18 4.8 5.4 0; 19 11.07 5.4 0; 20 17.69 5.4 0; 21 0 5.4 7.69; 22 4.8 5.4 7.69; 23 11.07 5.4 7.69; 24 17.69 5.4 7.69; 25 0 5.4 11.28; 26 4.8 5.4 11.28; 27 11.07 5.4 11.28; 28 16.73 5.4 11.28; 29 0 5.4 20.02; 30 4.8 5.4 20.02; 31 11.07 5.4 20.02; 32 16.73 5.4 20.02; 33 0 10.1 0; 34 4.8 10.1 0; 35 11.07 10.1 0; 36 17.69 10.1 0; 37 0 10.1 7.69; 38 4.8 10.1 7.69; 39 11.07 10.1 7.69; 40 17.69 10.1 7.69; 41 0 10.1 11.28; 42 4.8 10.1 11.28; 43 11.07 10.1 11.28; 44 16.73 10.1 11.28; 45 0 10.1 20.02; 46 4.8 10.1 20.02; 47 11.07 10.1 20.02; 48 16.73 10.1 20.02; 49 0 14.25 0; 50 4.8 14.25 0; 51 11.07 14.25 0; 52 17.69 14.25 0; 53 0 14.25 7.69; 54 4.8 14.25 7.69; 55 11.07 14.25 7.69; 56 17.69 14.25 7.69; 57 0 14.25 11.28; 58 4.8 14.25 11.28; 59 11.07 14.25 11.28; 60 16.73 14.25 11.28; 61 0 14.25 20.02; 62 4.8 14.25 20.02; 63 11.07 14.25 20.02; 64 16.73 14.25 20.02; 65 0 -1.4 0; 66 4.8 -1.4 0; 67 11.07 -1.4 0; 68 17.69 -1.4 0; 69 0 -1.4 7.69; 70 4.8 -1.4 7.69; 71 11.07 -1.4 7.69; 72 17.69 -1.4 7.69; 73 0 -1.4 11.28; 74 4.8 -1.4 11.28; 75 11.07 -1.4 11.28; 76 16.73 -1.4 11.28; 77 0 -1.4 20.02; 78 4.8 -1.4 20.02; 79 11.07 -1.4 20.02; 80 16.73 -1.4 20.02; MEMBER INCIDENCES 1 1 2; 2 2 3; 3 3 4; 4 5 6; 5 6 7; 6 7 8; 7 9 10; 8 10 11; 9 11 12; 10 13 14; 11 14 15; 12 15 16; 13 17 18; 14 18 19; 15 19 20; 16 21 22; 17 22 23; 18 23 24; 19 25 26; 20 26 27; 21 27 28; 22 29 30; 23 30 31; 24 31 32; 25 33 34; 26 34 35; 27 35 36; 28 37 38; 29 38 39; 30 39 40; 31 41 42; 32 42 43; 33 43 44; 34 45 46; 35 46 47; 36 47 48; 37 49 50; 38 50 51; 39 51 52; 40 53 54; 41 54 55; 42 55 56; 43 57 58; 44 58 59; 45 59 60; 46 61 62; 47 62 63; 48 63 64; 49 1 17; 50 17 33; 51 33 49; 52 2 18; 53 18 34; 54 34 50; 55 3 19; 56 19 35; 57 35 51; 58 4 20; 59 20 36; 60 36 52; 61 5 21; 62 21 37; 63 37 53; 64 6 22; 65 22 38; 66 38 54; 67 7 23; 68 23 39; 69 39 55; 70 8 24; 71 24 40; 72 40 56; 73 9 25; 74 25 41; 75 41 57; 76 10 26; 77 26 42; 78 42 58; 79 11 27; 80 27 43; 81 43 59; 82 12 28; 83 28 44; 84 44 60; 85 13 29; 86 29 45; 87 45 61; 88 14 30; 89 30 46; 90 46 62; 91 15 31; 92 31 47; 93 47 63; 94 16 32; 95 32 48; 96 48 64; 97 1 5; 98 5 9; 99 9 13; 100 2 6; 101 6 10; 102 10 14; 103 3 7; 104 7 11; 105 11 15; 106 4 8; 107 8 12; 108 12 16; 109 17 21; 110 21 25; 111 25 29; 112 18 22; 113 22 26; 114 26 30; 115 19 23; 116 23 27; 117 27 31; 118 20 24; 119 24 28; 120 28 32; 121 33 37; 122 37 41; 123 41 45; 124 34 38; 125 38 42; 126 42 46; 127 35 39; 128 39 43; 129 43 47; 130 36 40; 131 40 44; 132 44 48; 133 49 53; 134 53 57; 135 57 61; 136 50 54; 137 54 58; 138 58 62; 139 51 55; 140 55 59; 141 59 63; 142 52 56; 143 56 60; 144 60 64; 145 65 1; 146 66 2; 147 67 3; 148 68 4; 149 69 5; 150 70 6; 151 71 7; 152 72 8; 153 73 9; 154 74 10; 155 75 11; 156 76 12; 157 77 13; 158 78 14; 159 79 15; 160 80 16; *------------------------------------------------------------------------------ DEFINE MATERIAL START ISOTROPIC CONCRETE E 2.17185e+007 POISSON 0.17 DENSITY 23.5616 ALPHA 1e-005 DAMP 0.05 TYPE CONCRETE STRENGTH FCU 27579 END DEFINE MATERIAL *------------------------------------------------------------- MEMBER PROPERTY AMERICAN *Dados 145 TO 160 PRIS YD 0.5 ZD 0.5 *Columnas 49 TO 96 PRIS YD 0.4 ZD 0.4 *Trabes de liga 1 TO 12 97 TO 108 PRIS YD 0.45 ZD 0.3 *TRabes enbebidas 109 TO 144 PRIS YD 0.35 ZD 0.9 13 TO 15 22 TO 27 34 TO 39 46 TO 48 PRIS YD 0.35 ZD 0.7 16 TO 21 28 TO 33 40 TO 45 PRIS YD 0.35 ZD 0.5 *------------------------------------------------------------- CONSTANTS MATERIAL CONCRETE ALL *-------------------------------------- SUPPORTS 65 TO 80 FIXED *---------------------------------------------------- UNIT CM KG MEMBER RELEASE 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 END MX MY MZ UNIT METER KG LOAD 1 CARGA MUERTA SELFWEIGHT Y -1 FLOOR LOAD YRANGE 1 15 FLOAD -500 GY MEMBER LOAD *Carga Muros 1 TO 3 10 TO 12 97 TO 99 106 TO 108 UNI GY -1350 13 TO 15 22 TO 24 109 TO 111 118 TO 120 UNI GY -1179 25 TO 27 34 TO 36 121 TO 123 130 TO 132 UNI GY -1045 *Carga Pretil 37 TO 39 46 TO 48 133 TO 135 142 TO 144 UNI GY -250 *---------------------------------------------------- LOAD 2 CARGA VIVA FLOOR LOAD YRANGE 1 5 FLOAD -250 GY YRANGE 10 15 FLOAD -170 GY *---------------------------------------------------- LOAD COMB 3 CM + CV (SIN FACTORIZAR) 1 1.0 2 1.0 LOAD COMB 4 CM + CV (FACTORIZADAS) 1 1.4 2 1.6 *---------------------------------------------------- PERFORM ANALYSIS LOAD LIST 3 4 PRINT SUPPORT REACTION PRINT MEMBER FORCES ALL *---------------------------------------------------- UNIT CM KG LOAD LIST 4 START CONCRETE DESIGN CODE ACI FC 250 ALL FYMAIN 4200 ALL FYSEC 4200 ALL *Trabes de liga DESIGN BEAM 1 TO 12 97 TO 108 *Dados DESIGN COLUMN 145 TO 160 *Trabes Planta Baja DESIGN BEAM 13 TO 24 109 TO 120 *Columnas planta Baja DESIGN COLUMN 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 *Trabes 1er Nivel DESIGN BEAM 25 TO 36 121 TO 132 *Columnas 1er Nivel DESIGN COLUMN 50 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 *Trabes 2do Nivel (Azotea) DESIGN BEAM 37 TO 48 133 TO 144 *Columnas 2do Nivel DESIGN COLUMN 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 END CONCRETE DESIGN FINISH