Calculation of composite floor slabs in the service phase

The calculation of composite floor slabs in the use stage mainly includes the Calculation of flexural section load-bearing capacity , Calculation of shear section load-bearing capacity and deflection calculation of composite floor slabs.

Calculation of flexural section load-bearing capacity

The moment calculation of composite floor slabs in the use phase is divided into two cases: setting up temporary support and not setting up temporary support.

No setting up temporary support

In the positive bending moment section, the bending moment is:

M=M1G+M2G+M2Q

metal decking composite floor slab negative moment section with a bending moment of:

M=M2G+M2Q

Setting up temporary support

Positive and negative moment sections of composite floor slabs with bending moments:

M=M1G+M2G+M2Q

Note: 

M — — design value of bending moment of composite floor slab.

M1G — —composite floor slab weight in the calculation of the design .

M2G — — the design value of the bending moment in the calculated section for permanent loads other than the self-weight of the composite floor slab.

M2Q — — Design value of bending moments generated by variable loads in the calculated section.

Calculation of shear design for composite floor slabs

V= γV1G十V2G十V2Q

Note:

V — — Maximum shear design value of combined floor slabs

V1G — — Design value of the shear force generated by the self-weight of the composite floor slab in the calculated section

V2G — — Design value of the shear force generated in the calculated section by permanent loads other than the self-weight of the composite floor slabs

V2Q — — Design value of the shear force generated by the variable load on the calculated section; γ — — Support coefficients relating to support conditions during construction shall be taken from following Table

Calculation-of-composite-floor-slabs-in-the-service-phase

Deflection of composite floor slabs in the service phase

Deflection under standard composite of load effects

Deflection-under-standard-composite-of-load-effects

Deflection under quasi-permanent composite of load effects

Deflection-under-quasi-permanent-composite-of-load-effects

Note:

△s — —Deflection values of composite floor slabs by standard combination of loads

△q — —Deflection values of composite floor slabs by quasi-permanent combination of loads

△1GK  — — Deflection values of metal composite decks during the construction phase based on standard combinations of permanent Loads

△S2GK — — Deflection values of composite floor slabs according to γdgk and other standard combinations of permanent loads and calculated on the basis of short-term section bending stiffness.

△l2GK — — Deflection values of composite floor slabs according to γdgk and other standard combinations of permanent loads and calculated on the basis of long term section bending stiffness.

△SQ1K — — The value of the deflection calculated on the basis of the short-term section flexural rigidity B” under the action of the ith standard value of variable load.

△lGiK — — The value of the deflection calculated on the basis of the long term section flexural rigidity B” under the action of the ith standard value of variable load.

φci — — Combination factor for the ith variable load

φqi — —Quasi-permanent coefficient for the ith variable load

gk — — Self-weight of composite floor slabs (metal composite deck, steel and concrete)

γd  — — Coefficients, γd =0 for unsupported, γd =1 for others