Engineering and Technology Journal

Torsion is resisted well by closed form reinforcement, due to the circulatory nature of the torsion inducing shear flow stresses in a beam. Therefore, it will be more efficient to have strengthening schemes, which are wrapped in closed form around the cross section. An experimental work was carried out and used superplasticizer with mix 1:1.5 to improve the mechanical properties of mortar. 12 rectangular beams (50x120)mm and 1m length are cast, strengthened and tested under pure torsion. The Variables considered in the test program include: effect number of wire mesh layers ( unit ), this unit consists of two layers of wire mesh with skeletal steel, (2, 3, 4) units and effect spacing of CFRP strips, (100,160,200) mm c/c. Test results are discussed based on torque – rotation behavior and influence of parameters on ultimate torque and failure modes. Generally, using optimum dosage of super plasticizer (1.4 % of weight of cement) gave compressive strength 65.65 MPa. Increasing the number of units from 2 to 4(reinforcement near the surface of beam section) led to increased ultimate torque by (13.44 %) and from 2 to 3(uniformly distributed reinforcement) led to increases the ultimate torque by only (3.24 %). When the beams are strengthened with CFRP strips, the lowest and highest increase in torque is at 112 % (4-units,@200 spacing) and 312 % (4-units,@100 spacing), respectively. The ultimate torque of beams with CFRP strips @ 100 mm and 160 mm spacing is greater than beams with CFRP strips @ 200 mm spacing by ( 94.34,45.28) %, respectively for the group having 4-units.

This research is devoted to investigate the behavior of spherical ferrocement slabs under flexural loading. The main parameters considered in the analysis are the thickness of the slab, vertical and horizontal diameters, and the effect of number of wire mesh layers on the behavior of spherical. Analysis was done using the finite element software ANSYS V. 11, which is used for solving several problems of structural engineering. The 8-node iso-parametric brick elements in ANSYS are used to represent the mortar, the wire mesh layers are
considered as smeared layers elastic-perfectly plastic materials embedded within the
brick elements by assuming perfect bond between the mortar and steel.
An improvement was indicated in the behavior of the elements when changing the shape of the slab from straight to spherical slabs found in deflection about 64% (as indicated in ref. [1]). As well as increasing number of wire mesh layers from two to four and from two to six tend to increase the load capacity by 18% and 28% respectively.
The increase in the thickness and the vertical diameter cause decrease in deflection to 20% and 10% alternately.