# Shrinkage-Induced Response of Composite Steel-Concrete Slabs: A State-of-the-Art Review
## 3 Time-Dependent Responses of Composite Slabs
### Simply-Supported Composite Slabs  
The experimental program involving the long-term testing of simply-supported one-way composite slabs subjected to different loading conditions and prepared with different profiled sheeting were reported in [16; 18; 50; 51; 52; 53]. In this experimental work, all composite slabs increased in deflections over time due to shrinkage and due to creep induced from their self-weight and sustained loads. For example, five composite slab samples were cast on KF70(r) [23] steel sheeting and five slabs cast on KF40(r) [23] steel sheeting, with spans of 3100 mm [50; 51]. All slabs had the same cross-section (i.e., 1200-mm-wide and 150-mm-deep) and the moist curing was applied for six days from the day of casting. The samples were then placed in a simply-supported static configuration until 63 days of concrete age under self-weight only. After a period of 57 days of drying, the samples cast on KF70(r) [23] deck exhibited deflections in the range of 2.18-2.97 mm, while the samples cast on KF40(r) [23] had deflections within 2.72-3.33 mm (of the same order) already after 21 days of drying. These results highlighted the influence of shrinkage on the deflections of composite slabs. After 63 days from the casting date, sustained loads were applied on the specimens and these ranged from 0 (only self-weight) to 9.5 kN/m. Long-term results for 119 days of composite slabs prepared with different amounts of reinforcement ratios were reported in [16] together with the measurements of two reinforced concrete slab samples prepared with amounts of steel reinforcement that were equivalent to one adopted in the companion composite slabs. This selection of reinforcement aimed at differentiating between the role of non-symmetric steel reinforcement specified in a slab to the one of the non-uniform shrinkage gradients. All slabs were 3300-mm-long and two composite slabs were cast on Stramit Condeck HP\({}^{\text{\textregistered}}\)[21] steel sheeting with the propped condition. All samples were subjected to moist curing until 15 days from the day of casting. They were then placed in a simply-supported static configuration and subjected to their self-weight only. The composite slabs were allowed to dry only from the top surfaces, whereas the reinforced concrete slabs were allowed to dry from both top and bottom surfaces. These tests highlighted the role played by the non-uniform shrinkage gradient in influencing the long-term response. The companion composite and reinforced concrete slab samples  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref. **} & \multirow{2}{*}{**Sample**} & \multirow{2}{*}{\(f_{c}\) **1**} & \multirow{2}{*}{\(w_{sus}\) **1**} & \multirow{2}{*}{\(t_{0}\) **1**} & \multirow{2}{*}{\(t_{k}\) **1**} & \multirow{2}{*}{\(L\) (\(U_{0}\)) **1**} & \multirow{2}{*}{\(b\) **1**} & \multirow{2}{*}{\(D\) **1**} & \multirow{2}{*}{**Profiled Steel**} & \multirow{2}{*}{**Remarks**} \\ \cline{3-3} \cline{8-11}  & & **ID** & **[MPa]** & **[kN/m]** & **[Days]** & **[Days]** & **[mm]** & **[mm]** & **[mm]** & **[mm]** \\ \hline \multirow{4}{*}{[16]} & CS1 & \multirow{4}{*}{27.3} & \multirow{4}{*}{0} & \multirow{4}{*}{15} & \multirow{4}{*}{119} & 3300 & \multirow{4}{*}{900} & \multirow{4}{*}{180} & \multirow{4}{*}{Condex HP\({}^{\text{\textregistered}}\)[21]} & \\  & CS2 & & & & & & & & & \\ \cline{2-1  
exhibited different deflections even in the cases in which symmetric steel reinforcement was specified. In this case, the composite specimen underwent higher deflections than the reinforced concrete sample by about 54% and this difference was simply attributed to the non-symmetric drying conditions (as these companion samples possessed similar amounts of symmetric reinforcement). Similar considerations were also drawn for the companion specimens without top reinforcement while in this case the differences in deflections were even greater.