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=M_1G+M_2G+M_2Q

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

M=M_2G+M_2Q

Setting up temporary support

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

M=M_1G+M_2G+M_2Q

Note: 

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

M_1G — —composite floor slab weight in the calculation of the design .

M_2G — — the design value of the bending moment in the calculated section for permanent loads other than the self-weight of the composite floor slab.

M_2Q — — Design value of bending moments generated by variable loads in the calculated section.

Calculation of shear design for composite floor slabs

V= γV_1G十V_2G十V_2Q

Note:

V — — Maximum shear design value of combined floor slabs

V_1G — — Design value of the shear force generated by the self-weight of the composite floor slab in the calculated section

V_2G — — Design value of the shear force generated in the calculated section by permanent loads other than the self-weight of the composite floor slabs

V_2Q — — 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

Deflection of composite floor slabs in the service phase

Deflection under standard 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

△^S_2GK — — Deflection values of composite floor slabs according to γ_dg_k and other standard combinations of permanent loads and calculated on the basis of short-term section bending stiffness.

△^l_2GK — — Deflection values of composite floor slabs according to γ_dg_k and other standard combinations of permanent loads and calculated on the basis of long term section bending stiffness.

△^S_Q1K — — 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.

△^l_GiK — — 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.

φ_ci — — Combination factor for the ith variable load

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

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

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