The shear behavior of the reinforced concrete plates at the junction of Rectangular walls were experimentally studied. Four tests were conducted on Rectangular reinforced concrete plates which were simply set on edge supports. The centrically located Rectangular walls with different aspect ratios were connected to the plates. The load was applied eccentrically with different amount of eccentricity for each plate and was increased with a monotonic procedure. All plates were failed at the brittle-punching mode of failure. Following the punching failure, the plates were forced to carry increasing displacements until reaching to extremely large rotations while stabilizing a post-peak strength. The load-deflection behavior of the connections was simulated performing the nonlinear analyses of numerical models of the plates using specially purposed software, ATENA. The results of the experimental tests were compared with the outputs of the analyses and with the predictions of ACI and EC2 codes.

Methods to improve bearing capacity of Footing resting of collapsing soil can, in fact, take two approaches, improving soil strength properties and intrusion of reinforcing sorces into soil. The Footing is modeled by a square steel plate 0.1 by 0.1 m. The Footing is loaded as to have a stress of 40 kPa and settlement is receded in dry and in soaking conditions. Two depths of the geo-mesh reinforcement are used, one B (B is width of Footing) and 0.5B. For one B depth, three different square sizes of geo-mesh are used, 4B, 6B, and 8B. For the reinforcement depth of 0.5B the three sizes of the geo-mesh used are, 3.5B, 5.5B, and, 7.5B. Results reveal that the best improvement obtained is the case of square geo-mesh width of 7.5B and located at depth of B/2 under Footing, with an improvement in terms of collapse settlement of 35%, and a settlement reduction in dry condition of 50%. The least improvement is the case of square geo-mesh with width of 4B and depth of one B, and it was really negligible, about 4% decrease in collapse settlement. Other cases varied between the two mentioned ratios. For findings of study, author recommends not to use geomesh size less than size of Footing and not to place it in a depth more than half Footing width. As such, in a whole, the effectiveness of geomesh in reducing the settlement of collapsing soil is obvious if used in proper way.

An experimental study is carried out to improve the bearing capacity of soils by using geotextile. In the present study geotextile (tire reinforcement) is used as geotextile, whereas sand is used as a soil medium. This research work presents the results of laboratory load tests on model square Footings supported on reinforced sand beds. A total of twenty-seven load tests are conducted to evaluate the effects of single layer reinforcement placed below square model Footings. The parameters of the testing program of the research work are the depth of reinforcement, the plan area of reinforcement, and the number of reinforcements. From the experimental data, it is indicated that there is an optimum reinforcement depth at which the bearing capacity is the highest. Also, the optimum size of reinforcement is found to be 1.5 B×1.5 B irrespective of the type of reinforcing materials used. The bearing capacity of reinforced sand is also found to increase with the number of reinforcement layer and reinforcement size when the reinforcement is placed within a certain effective zone with high relative density. The optimum placement position of geotextile is found to be 0.5B to 0.75B from the base of the Footing .The tests are done at two different relative densities, i.e., 40% and 60%. The bulk unit weight of sandy soil is 14.81 KN/m³. Maximum gain in load carrying capacity is obtained when depth of reinforcement/width of Footing (Dr/B) is 0.5 at relative density of 40% and 0.75 at a relative density of 60%.In addition, the data indicate that increasing reinforcement beyond a certain value would not bring about further increase in the bearing capacity of the soil.

The rigid base proximity (such as stiff rock) under a relatively thin sand stratum and employing a 3D reinforcement (e. g. geocell) can tend to significant improvement in the bearing pressure of shallow Footings. In this study, the behavior of circular Footings located on unreinforced and geocell-reinforced thin sand layer was investigated. The simultaneous or individual effect of Footing dimensions, sand layer thickness, and geocell reinforcement on the bearing pressure and settlement was studied by conducting large-scale model tests. The influence of soil layer thickness on Footing behavior was elucidated by considering optimum dimensions and location for geocell reinforcement. Based on the results, improvement in the bearing capacity and settlement reduction for both unreinforced and reinforced Footing bed was seen when the sand layer thickness is lower than two times of the Footing width. Additionally, the effectiveness depth of the rigid base for both cases was obtained two times of Footing width. The combination of geocell reinforcement and rigid base as lateral and vertical confinement factors, led to increase in the bearing capacity and settlement reduction at the failure point up to 45% and 53%, respectively. The tests results were served to define new factors extending classical bearing capacity equations for Footings located on thin soil at reinforced and unreinforced cases. The comparision of this study’, s achievement with the previous investigations confirmed their good agreement.

The results of laboratory model tests and numerical analysis on circular Footings supported on sand bed under incremental cyclic loads are presented. The incremental values of intensity of cyclic loads (loading, unloading and reloading) were applied on the Footing to evaluate the response of Footing and also to obtain the value of elastic rebound of the Footing corresponding to each cycle of load. The effect of sand relative density of 42%, 62%, and 72% and different circular Footing area of 25, 50, and 100cm2 were investigated on the value of coefficient of elastic uniform compression of sand (CEUC). The results show that the value of coefficient of elastic uniform compression of sand was increased by increasing the sand relative density while with increase the Footing area the value of coefficient of elastic uniform compression of sand was decreases. The responses of Footing and the quantitative variations of CEUC with Footing area and soil relative density obtained from experimental results show a good consistency with the obtained numerical result using "FLAC-3D".