Load Combinations According to BS, ACI & Indian Codes

REF:- Reinforced Concrete Design Manual,2008,CSI,using different codes

ACI-318-2008, Design Load Combinations The design load combinations are the various combinations of the load cases for which the structure needs to be designed. For ACI 318-08, if a structure is subjected to dead load (D), live load (L), pattern live load (PL), snow (S), wind (W), and earthquake (E) loads, and considering that wind and earthquake forces are reversible, the following load combinations may need to be considered(ACI 9.2.1): ************************************************************************** 1.4D

(ACI 9.2.1)

************************************************************************** 1.2D + 1.6L

(ACI 9.2.1)

************************************************************************** 1.2D + 1.6 (0.75 PL)

(ACI 13.7.6.3)

************************************************************************************* 0.9D ± 1.6W,,,,,,,,,,,,,,,,,if W is based on service-level wind loads 0.9D + 1.0W 1.2D + 1.0L ± 1.0W 1.2D+1.0L±1.6W,,,if W is based on service-level wind loads (ACI 9.2.1) ************************************************************************************* 0.9D ± 1.0E 0.9D ± 1.4E ,,, ,,,if E is based on service-level forces 1.2D + 1.0L ± 1.0E

(ACI 9.2.1)

************************************************************************** 1.2D + 1.6L + 0.5S 1.2D + 1.0L + 1.6S 1.2D + 1.6S ± 0.8W 1.2D + 1.0L + 0.5S ± 1.6W 1.2D + 1.0L + 0.2S ± 1.0E

(ACI 9.2.1)

************************************************************************** The IBC 2006 basic load combinations (Section 1605.2.1) are the same.

The structural effects of load T shall be considered in combination with other loads. The load factor on T shall not have a value less than 1.0 (ASCE-SEI-710-2010) &( ACI-318M-2011, 9.2.3-Self-straining effect ). **************************************************************************** 1.2D + 1.2 T + 1.6L ,,, Design of Concrete Structures, Nilson, Darwin & Dolan,2010,14th ed, Table 1.2 page 18 & Reinforced Concrete-a Fundamental approach-1,E.G.Nawy-5th ed,2005, page 82 ****************************************************************************

BS-8110-1997, Design Load Combinations The design load combinations are the various combinations of the load cases for which the structure needs to be designed. The design load combinations are obtained by multiplying the characteristic loads by appropriate partial factors of safety, γf (BS 2.4.1.3). For BS 8110-1997, if a structure is subjected to dead load (D), live load (L), pattern live load (PL), snow (S), and wind (W) loads, and considering that wind forces are reversible, the following load combinations may need to be considered (BS 2.4.3). ********************************************************************** 1.4D 1.4D + 1.6L

(BS 2.4.3)

********************************************************************* 1.4D + 1.6(0.75PL)

(BS 2.4.3)

********************************************************************* 1.0D ± 1.4W 1.4D ± 1.4W 1.2D + 1.2L ± 1.2W

(BS 2.4.3)

********************************************************************* 1.4D + 1.6L + 1.6S 1.2D + 1.2S ± 1.2W 1.2D + 1.2L + 1.2S ± 1.2W

(BS 2.4.3)

Indian Code- Design Load Combinations IS-875-5-1987(2003),General Combinations a) DL b) DL+LL c) DL+ WL d) DL+EL e) DL+TL f) DL+LL+ WL g) DL+LL+EL h) DL+ LL+ TL i) DL+ WL+ TL k) DL+EL+ TL m) DL+LL+WL+TL n) DL+LL+EL+TL (( DL = dead load, LL = imposed load, WL = wind load, EL = earthquake load, TL = temperature load ). IS 1893-2002-Pt.1-6.3.1.1 Load factors for plastic design of steel structures In the plastic design of steel structures, the following load combinations shall be accounted for: 1) 1.7(DL.+LL ) 2) 1.7(DL*EL) 3) 1.3(DL+LL+EL) IS 1893-2002-Pt.1-6.3.1.1 Partial safety factors for limit state designof reinforced concrete and prestressed concrete structures In the limit state design of reinforced and prestressed concrete structures, the following load combinations shall be accounted for: 1) 1.5( DL+LL)

2) 1.2( DL+LL+EL) 3) 1.5( DL+EL) 4) 0.9DL* 1.5EL

**************************************************************************************** Other loads to be considered, but not listed in the Code (Table 18) include 0.75 (1.4 DL + 1.4 TL + 1.7 LL) 1.4 (DL + TL)

Reinforced Concrete Design,Pillai & Menon,3.6.3 page 89

Serviceability limit states : 1.0 (DL + LL) 1.0 (DL + EL) 1.0 DL + 0.8 LL + 0.8 EL Reinforced Concrete Design,Pillai & Menon,3.6.3 page 88 *************************************************************************