S. Karshenas et Sm. Heinrich, DYNAMIC MODELING OF SLAB FORMWORK DURING CONCRETE PLACEMENT, Journal of structural engineering, 120(7), 1994, pp. 2199-2217
Citations number
7
Categorie Soggetti
Engineering, Civil","Construcion & Building Technology
The static and dynamic loads applied to hand-set slab formworks during
the pouring of a concrete slab are investigated. The spatial distribu
tion and time history of the concrete-placement loads and the resultin
g formwork response depend on the equipment used for placing the concr
ete. The impact loads associated with the crane-and-bucket method of c
oncrete placement are investigated. A number of factors affect the mag
nitude of the concrete load when emptying a bucket. These factors incl
ude the height of fall, concrete slump, bucket-discharge rate, and the
dynamic properties of the slab formwork. A single-degree-of-freedom,
variable mass, dynamic model is developed for calculating the concrete
-placement loads by taking into consideration the above-mentioned fact
ors. The concrete-flow rate from a bucket is modeled as a lognormal wh
ite-noise random process. To verify the validity of the developed mode
l, several lab experiments were performed using a 2.4 m x 2.4 m (8 ft
x 8 ft) formwork deck. The lab's overhead crane was used to lift the c
oncrete-filled buckets to various heights above the deck before discha
rging the concrete. Pressure and displacement transducers were attache
d to the formwork deck for measuring the load intensity and deck displ
acements.