FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

More documents

Recommendations

Info

10 DESIGNING THE FOUNDATION Volume II 10.7 Open/Shallow Foundations Open/shallow foundations are recommended for areas that are exposed to moving floodwaters and moderate wave actions but are not exposed to scour and erosion, which can undermine shallow footings. Open/shallow foundations are recommended for some riverine areas where an open foundation style is desirable and for buildings in Coastal A Zone where scour and erosion is limited. In Coastal A Zones where the predicted scour and erosion depths extend below the achievable depth of shallow footings and in Coastal A Zone where scour and erosion potential is unknown or cannot be accurately predicted, open/deep foundations should be installed. FEMA P-550 contains designs for open shallow foundations. The foundations are resistant to moving floodwaters and wave action, but because they are founded on shallow soils, they can be vulnerable to scour and erosion. Figure 10‑15. Profile of an open/ shallow foundation SOURCE: ADAPTED FROM FEMA P-550, CASE D 10-34 COASTAL CONSTRUCTION MANUAL
Volume II DESIGNING THE FOUNDATION 10 The FEMA P-550 designs make use of a rigid mat to resist lateral forces and overturning moment. Frictional resistance between the grade beams and the supporting soils resist lateral loads. The weight of the foundation and the elevated structure resist uplift forces. Because the foundation lacks the uplift resistance provided by piles, foundation elements often need to be relatively large to provide sufficient dead load to resist uplift, particularly when they are submerged. Grade beams need to be continuous because, as is shown in Section 10.9, discrete foundations that have sufficient capacity to resist lateral and uplift forces without overturning are difficult to design. FEMA P-550 contains two types of open/shallow foundations. The foundation type shown in Figure 10-15 uses a matrix of grade beams and concrete columns to elevate the building. The grade beam shown in Figure 10-15 should not be used as structural support for a concrete slab that is below an elevated building in Zone V. If the grade beam is used to support the slab, the slab will be considered the lowest floor of the building, which will lead to the insurance ramifications described in Section 10.6.2. When used to support wood framing, the columns of open/shallow foundations are typically designed as cantilevered beam/columns subjected to lateral forces, gravity forces and uplift forces from the elevated structure and flood forces on the foundation columns. Because of the inherent difficulty of creating moment connections with wood framing, the connections between the top of the columns and the bottom of the elevated structure are typically considered pinned. Maximum shear and moment occurs at the bottom of the columns, and proper reinforcement and detailing is needed in these areas. Also, because there are typically construction joints between the tops of the grade beams and the bases of the columns where salt-laden water can seep into the joints, special detailing is needed to prevent corrosion. Designing an open/shallow foundation that uses concrete columns and elevated concrete beams can create a frame action that increases the foundation’s ability to resist lateral loads. This design accomplishes two things. First, the frame action reduces the size of the columns and in turn reduces flood loads on them, and second, when properly designed, the elevated beams act like the tops of a perimeter foundation wall. Homes constructed to one of the designs contained in prescriptive codes can be attached to the elevated concrete beams with minimal custom design. Unlike deep, driven-pile foundations, both types of open/shallow foundations can be undermined by erosion and scour. Neither foundation type should be used where erosion or scour is anticipated to expose the grade beam. 10.8 Closed/Shallow Foundations Closed/shallow foundations are similar to the foundations that are used in non-coastal areas where flood forces are limited to slowly rising floods with no wave action and only limited flood velocities. In those areas, conventional foundation designs, many of which are included for residential construction in prescriptive codes and standards such as the 2012 IRC and ICC 600-2008, may be used. However, these codes and standards do not take into account forces from moving floodwaters and short breaking waves that can exist inland of Coastal A Zones. Therefore, caution should be used when using prescribed foundation designs in areas exposed to moving floodwaters and breaking waves. FEMA P-550 contains two foundation designs for closed/shallow foundations: a stem wall foundation and a crawlspace foundation. Crawlspace foundation walls in SFHAs must be equipped with flood vents COASTAL CONSTRUCTION MANUAL 10-35
Page 1 and 2:
Coastal Construction Manual Princip
Page 3 and 4:
All illustrations in this document
Page 5 and 6:
PREFACE Volume II Chapter 8 - Site-
Page 7 and 8:
1 CHAPTER TITLE Contents COASTAL CO
Page 9 and 10:
Volume II CONTENTS Chapter 9. Desig
Page 11 and 12:
Volume II CONTENTS Chapter 11. Desi
Page 13 and 14:
Volume II CONTENTS 12.5 Water and W
Page 15 and 16:
Volume II CONTENTS 15.4.1 Evaluatin
Page 17 and 18:
Volume II CONTENTS Figure 9-10. Roo
Page 19 and 20:
Volume II CONTENTS Figure 11-3. Hou
Page 21 and 22:
Volume II CONTENTS Figure 11-47. Da
Page 23 and 24:
Volume II CONTENTS Chapter 15 Figur
Page 25 and 26:
Volume II CONTENTS Table 10-9. Adva
Page 27 and 28:
Volume II CONTENTS Example 8.4. Flo
Page 29 and 30:
1 CHAPTER TITLE COASTAL CONSTRUCTIO
Page 31 and 32:
Volume II PRE-DESIGN CONSIDERATIONS
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
8 DETERMINING SITE-SPECIFIC LOADS V
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
9 DESIGNING THE BUILDING Volume II
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164: 9 DESIGNING THE BUILDING Volume II
Page 181 and 182: 1 CHAPTER TITLE COASTAL CONSTRUCTIO
Page 183 and 184: Volume II DESIGNING THE FOUNDATION
Page 213: Volume II DESIGNING THE FOUNDATION
Page 219 and 220: 10 DESIGNING THE FOUNDATION Volume
Page 229 and 230: 1 CHAPTER TITLE COASTAL CONSTRUCTIO
Page 231 and 232: Volume II Designing the builDing en
Page 265 and 266:
Volume II Designing the builDing en
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Page 285 and 286:
12 INSTALLING MECHANICAL EQUIPMENT
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
13 CONSTRUCTING THE BUILDING Volume
Page 299 and 300:
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
14 MAINTAINING THE BUILDING Volume
Page 331 and 332:
Page 333 and 334:
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
1 CHAPTER TITLE COASTAL CONSTRUCTIO
Page 343 and 344:
Volume II RETROFITTING BUILDINGS FO
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
1 CHAPTER TITLE Acronyms COASTAL CO
Page 365 and 366:
Volume II ACRONYMS H HMA Hazard Mit
Page 367 and 368:
Volume II ACRONYMS T TMS The Masonr
Page 369 and 370:
GLOSSARY Volume II Basement - Under
Page 371 and 372:
GLOSSARY Volume II Conditions Great
Page 373 and 374:
GLOSSARY Volume II F Federal Emerge
Page 375 and 376:
GLOSSARY Volume II G Gabion - Rock-
Page 377 and 378:
GLOSSARY Volume II Location - The l
Page 379 and 380:
GLOSSARY Volume II O Open foundatio
Page 381 and 382:
GLOSSARY Volume II Risk tolerance -
Page 383 and 384:
GLOSSARY Volume II safe living cond
Page 385 and 386:
GLOSSARY Volume II Z Zone A - Under
Page 387 and 388:
INDEX Volume II Building envelope,
Page 389 and 390:
INDEX Volume II stillwater flood de
Page 391 and 392:
INDEX Volume II Floodborne debris d
Page 393 and 394:
INDEX Volume II I IBHS (see Insuran
Page 395 and 396:
INDEX Volume II date of constructio
Page 397 and 398:
INDEX Volume II Seawall, 7-7, 7-17,
Page 399 and 400:
INDEX Volume II velocity pressure,
show all

FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

Create successful ePaper yourself

Delete template?

Save as template?