{"id":364,"date":"2024-01-26T21:35:05","date_gmt":"2024-01-27T05:35:05","guid":{"rendered":"https:\/\/www.fwhb.ca\/?page_id=364"},"modified":"2024-08-23T11:08:05","modified_gmt":"2024-08-23T18:08:05","slug":"limit-states-design-lsd","status":"publish","type":"page","link":"https:\/\/www.fwhb.ca\/?page_id=364","title":{"rendered":"Limit States Design (LSD)"},"content":{"rendered":"\n

Loads applied on the formwork and falsework <\/h4>\n\n\n\n

In Table 2 of the standard, the loads are defined as followed<\/p>\n\n\n\n

DL<\/td>Dead load<\/td>Forming and shoring equipment self-weight<\/td><\/tr>
LL<\/td>Live load<\/td>Workers and tools<\/td><\/tr>
C<\/td>Concrete<\/td>Fresh concrete weight (vertical)<\/td><\/tr>
P<\/td>Concrete pressure<\/td>Lateral concrete pressure (horizontal)<\/td><\/tr>
W<\/td>Wind load<\/td>Wind load on braces and lateral supports<\/td><\/tr>
H<\/td>Horizontal loads<\/td>Other loads then the lateral concrete pressure and wind load<\/td><\/tr>
E<\/td>Environmental loads<\/td>Site specific conditions<\/td><\/tr>
CL<\/td>Additional construction loads<\/td>Major concrete placing ands screeding equipment or other site specific conditions<\/td><\/tr>
ML<\/td>Material loads<\/td>Site specific material storage and falsework and access<\/td><\/tr>
PT<\/td>Post tensioning loads<\/td>For pre-stress concrete elements<\/td><\/tr><\/tbody><\/table>
Load types and definitions, Clause 5.3<\/figcaption><\/figure>\n\n\n\n
Load combinations<\/h5>\n\n\n\n

From Table 5 of the standard, the load combinations and the load factors (\\(\\alpha\\))<\/strong> are defined as the following<\/p>\n\n\n\n

Load Cases (LC)<\/th>DL<\/th>LL<\/th>C<\/th>P<\/th>W<\/th>H<\/th>E<\/th>CL<\/th>ML<\/th>PT<\/th><\/tr><\/thead>
Direction<\/td>V<\/td>V<\/td>V<\/td>H<\/td>V\/H<\/td>H<\/td>V\/H<\/td>V\/H<\/td>V<\/td>V\/H<\/td><\/tr>
LC1<\/td>1.00<\/td>–<\/td>–<\/td>–<\/td>1.50<\/td>1.50<\/td>1.50<\/td>–<\/td>–<\/td>–<\/td><\/tr>
LC2<\/td>1.25<\/td>1.50<\/td>1.50*<\/td>1.50<\/td>1.50<\/td>1.50<\/td>1.50<\/td>1.50<\/td>–<\/td>–<\/td><\/tr>
LC3<\/td>1.25<\/td>1.50<\/td>1.50<\/td>–<\/td>–<\/td>1.50<\/td>–<\/td>–<\/td>1.50<\/td>1.00<\/td><\/tr><\/tbody><\/table>
Load cases and load factors (\\(\\alpha\\))<\/strong>, Clause 6.3.2
* refer to clause 6.3.2.5 Reduction of concrete load factor
( V: vertical loads and H: horizontal loads )<\/figcaption><\/figure>\n\n\n\n

Where the load cases are defined as follow<\/p>\n\n\n\n

LC1<\/td>Unloaded falsework and formwork or no concrete load. This load case is mostly affected by the wind horizontal pressure (W).<\/td><\/tr>
LC2<\/td>Falsework and formwork during concrete placement. For must falsework LC2 = 1.25DL + 1.5LL+1.5C. Since DL is relatively small compared to LL and C we use for simplicity LC2 = 1.5(DL+LL+C).<\/td><\/tr>
Lc3<\/td>Loaded falsework and formwork after concrete placement.<\/td><\/tr><\/tbody><\/table>
Load cases description, Clause 6.3.2<\/figcaption><\/figure>\n\n\n\n
*Reduction of concrete load factor<\/h5>\n\n\n\n

The load factor \\(\\alpha C\\) can be reduce if the placed concrete surface area<\/strong> supported by one element (stringer, post) is greater than \\(12.5m^2\\). Clause 6.3.2.5.1 specify the formula and the load factor range, this clause is not cover here because it is rarely used. It would apply to falsework design with a \\(12ft*12ft\\) or greater post spacing.

The load factor \\(\\alpha C\\) can be reduce if the placed concrete depth<\/strong> is greater than \\(0.55m\\). As per Clause 6.3.2.5.2, for \\(LL=1.90kPa\\), \\(\\alpha C\\) varies from 1.50 for depth less than \\(0.55m\\) to 1.25 for depth greater than \\(1.25m\\) as per the formula below.

\\(\\alpha C=1.25\\leq(0.5+\\sqrt{\\frac{1.75}r})\\times1.5\\leq1.50\\)<\/p>\n\n\n\n

where \\(r=\\frac{C}{LL}\\)
\\(C = \\rho_c*h\\)
\\(\\rho_c = 24 \\frac{kN}{m^3}\\)
\\(h=\\) concrete depth
<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Concrete load factor \\(\\alpha C\\) as a function of the concrete depth \\(h\\) measured in meters<\/p>\n\n\n\n

<\/div>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Concrete load factor \\(\\alpha C\\) as a function of the concrete depth \\(h\\) measured in inches<\/p>\n","protected":false},"excerpt":{"rendered":"

Loads applied on the formwork and falsework In Table 2 of the standard, the loads are defined as followed DL Dead load Forming and shoring equipment self-weight LL Live load Workers and tools C Concrete Fresh concrete weight (vertical) P Concrete pressure Lateral concrete pressure (horizontal) W Wind load Wind load on braces and lateral … Continue reading Limit States Design (LSD)<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-364","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=\/wp\/v2\/pages\/364","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=364"}],"version-history":[{"count":9,"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=\/wp\/v2\/pages\/364\/revisions"}],"predecessor-version":[{"id":829,"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=\/wp\/v2\/pages\/364\/revisions\/829"}],"wp:attachment":[{"href":"https:\/\/www.fwhb.ca\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}