Effect of size and depth on capacities of strip footings in limiting settlement approach

Structural and geotechnical engineers very often seek different options while deciding foundation sizes for buildings. In this research, the effect of different sizes and depths of strip footings below existing ground are studied based on the load bearing capacity using Geo5 spread footing software. Only vertical loadings were taken into account for this study. Four different strip footing widths (1.0m, 1.5m, 2.0m and 2.5m) were modeled under three different loads, 260kN, 600kN and 1000kN. The ground profile considered in this work was having a 2.0m thick weak layer at 6.0m below the existing ground level. Results showed that as the depth of footing increases, the depth of influence underneath the footing and settlement decreases. Also, it was noticed that as the footing width increases, the influence zone’s depth below the footing that passing the weak layer increases.

Compression Load Tests on Composite Foundations of Spread Footing Anchored by Helical Anchors

This study elucidates the compression behavior of a type of composite foundation of spread footing anchored by helical anchors. Three composite foundations were installed at a field site, and compression load testing was carried out on each foundation. Both the site conditions and the load tests were documented comprehensively. The compression load-settlement curves of composite foundations exhibit an initial linear-elastic segment, a curve transition, and a final linear region, and their capacities should be interpreted from the load-settlement curves. Five representative interpretation criteria (Chin, Terzaghi and Peck, slope tangent, tangent intersection, and L1–L2) were employed to determine the capacity of each foundation. Both the helical anchors and the footing share compression loadings on the composite foundation. Soil pressure cells at the center, near the edge, and at the corner of the footing represent a distribution from the lower, middle, and higher ranges of incremental soil pressures underneath the footing. Helical anchors underneath the footing approximately share 60%–80% of total load applied on the composite foundation pier, and higher compression resistance of a composite foundation can be obtained by increasing the footing embedment depth and the number of helical anchors underneath the footing.

The effect of wind- soil- structure interaction on the longitudinal response of high-rise buildings

In this work, the modelling of the wind impact on the standard tall building of CAARC (Commonwealth Advisory Aeronautical Council), which is placed on a surface spread footing, is done numerically utilizing the ABAQUS program. The wind is demonstrated as an exponential way in the boundary layer of the atmosphere. Then, stream turbulence is modeled by the ILES technique and a cosimulation is accepted to exchange non-uniform loads from fluid to structural nodes. Damping of the structure is controlled by the Rayleigh strategy. Mechanical reaction of the footing-soil framework is modeled utilizing direct strategy. Infinite boundary conditions have been added to the numerical model for the simulation of free boundaries, and reasonable contact elements for sliding and separating between subsurface components are considered. Finally, fluid solutions and structural reactions are compared with the mean and root mean squares of experimental estimations on an extensive range of reduced speeds. Numerical results for the framework of soil-structure systems were compared with base conditions without association of soil-structure interaction. It is concluded that dynamic properties and reactions of the building influence soil-structure interaction and accordingly the planners should consider these parameters keeping in mind to guarantee the practical designing.

A comparative study in flexure and shear design of spread footings

The design of spread footings is a field widely explored in structural engineering being the flexure and shear design verified by the use of codes. The objective of this paper consists in a comparative study of spread footing design between the Brazilian’s code, Eurocode and American’s code. The methodology considered an analytical analysis with three different examples in the flexure and shear design of the spread footings with different loads and footing height. The results show that the American’s code presented the minimum required value of reinforcement rates ​​in all examples and also was the only code that verified the punching and shear effect for all studied cases. In Eurocode flexure design, the results show that in the most examples, the reinforcement rate is higher than that considered by the other codes. The Brazilian code presented an inconsistency in the verification of the punching effect for one of the studied examples, requiring, therefore, a review and a modification of the code.

Structural condition assessment of a reinforced concrete driveway

The reinforced concrete structure of a driveway built in the eighties of the 20th century is under consideration. It is a single-storey structure with a length of approx. 66.00 m, made in the form of a reinforced concrete skeletal structure, consisting of 7 frames with cantilevers, spaced at 9.00 m: 3 frames in the horizontal part of the driveway are three-span ones, and 4 in the sloping part are single-span frames. The driveway frame main beams have a rectangular cross-section and are based on pillars that have been placed on the spread footing these elements form a monolithic structure. Prefabricated reinforced concrete hollow floor plates were laid on them in the central part of the driveway, and in the outer parts the driveway floor was made of hollow clay slab blocks (Ackerman type). At the time of investigation, the upper layers of the driveway consisted of a surface waterproofing layer, a concrete slab of approx. 10 cm thickness made on a 1 cm sand layer. However, no internal waterproofing layer was found as was in the original design. The paper describes the process of determining the current technical condition of the reinforced concrete driveway structure, paying attention to the design and construction of the object, its operation (including the issues of durability of concrete under the conditions of possible impacts of the marine environment). Static and strength calculations were also performed (supported by concrete and reinforcement tests) and the conditions for further operation of the driveway were analyzed as well as concepts of rehabilitation.