Calculation of Building Heat Losses through Slab-on-Ground Structures Based on Soil Temperature Measured In Situ

The article aims to assess the effects of soil temperature measured in situ on the heat loss analyses of a building. Numerical analyses and in situ measurements of soil temperature profiles for real conditions under a residential building (profile I) in Poland and under the area outside the building (profile II) were performed. Based on the measurement results, a proprietary geometric model of the partition was proposed. The heat flux and heat flow results obtained for reliable models are 4.9% and 6.9% higher compared to a model based on a typical meteorological year for the wall–foundation system and 10.0% and 10.1% higher for the slab-on-ground structure for profile I. The adoption of temperatures from the area outside the building as the boundary condition (profile II) results in greater differences between the obtained results. The difference in heat flow obtained in the numerical analyses for profiles I and II is about 2 W/m2, both for the wall–foundation system and for the slab-on-ground structure calculations. The adoption of temperatures for the ground outside the building led to overestimation in the heat flux calculations, this being due to lower temperatures in these particular layers of the ground.

Bearing Characteristics of Diaphragm Wall Foundation under Vertical and Combined Load

To investigate the bearing characteristics of diaphragm wall foundation under combined load, the results from elasto-plastic analyses of 3D finite element models (FEM) were presented in this study. The vertical load of the diaphragm wall foundation is borne by inner and outer side resistance, resistance of soil core and the end of wall, respectively. Moreover, the sum of end resistance and soil core resistance accounts for about 75% of the vertical load. The mobilization mechanism and distribution of side resistance of the foundation were also analyzed. It is clarified that the mobilization characteristics of inner and outer side resistance of the wall are completely opposite. Due to the combined load, the horizontal load has an amplification effect on the settlement of the foundation. Additionally, the calculation methods of the Eight-component Winkler spring model and rigid pile displacement were used for determining the vertical load-bearing capacity and the overturning stability. A comparison between results from the FEM and the theoretical calculation methods showed that the results of the numerical simulation properly coincided with that of the displacement solution of theoretical model. The conclusions obtained by the above methods all indicate that the foundation has the characteristics of overall overturning failure under the combined load.

INVESTIGATING THE BEHAVIOR OF PILED RAFT FOUNDATION IN CORE WALL FOUNDATION OF HIGH-RISE BUILDINGS

Core structure is an indispensable part of high buildings. Normally, the foundation of the core structure has a raft of larger size than the other foundations in the same project; therefore, the foundation of the core structure can be viewed as a small piled raft foundation. Currently, when calculating the piled foundation of the core, it is mostly assumed that the piles system will bear all the project loads. But this calculation method is not suitable for the actual constructions as well as does not make full use of the bearing capacity of the structure and the ground, leading to using more materials and causing more waste. Core structure aims to increase both stiffness and horizontal load capacity in high-rise buildings, so the moment inside the core transmitted to the foundation is very large. One of the shortcomings of the Plaxis 3D Foundation software is its inability to declare the moment affecting on the foundation due to the loads in this program just includes distributed loads, line loads and point loads in the geometry model. Consequently, when using Plaxis 3D Foundation software to calculate the core wall foundation of high-rise buildings, this moment is converted into an equivalent pair of moments. The research shows that when the core foundation of a high-rise building is placed on soft soil, the pile carries 96%, most of the load transmitted to the foundation. However, when the foundation is placed on hard soil, the soil surrounding the raft will bear about 10% of the load transmitted to the foundation. If this matter is skipped, there will be a large error in calculation and design

Compressive Capacity of Triangular Screw Piles Group Embedded in Soft Clay

Screw piles are used in different projects such as underpinning, lateral support of retaining wall, foundation of tower and under pipeline. In recent years, the use of screw piles became wide in all world as a result of low cost, ease of installation and need simple machines to construct. A laboratory study of triangle pattern of screw piles group embedded in soft clay and extended to sand soil layer is carried out. Different parameters are investigated such as spacing between piles, number of helix plates and slenderness ratios L/ D. The results of this study showed that the efficiency of screw piles group increases when group extended to sandy layer. Also, a study showed that the compressive capacity of triangular pattern group decreases with increase spacing between piles for group of single and double helix plates. The percent’s of reduction are (61, 22, 15) % and (56, 25, 29) % for single and double helix group respectively

L-shaped reinforced concrete retaining wall design: cost and sizing optimization

In the context of this study, the design of L-shaped reinforced concrete retaining walls have been scrutinized parametrically depending on the simultaneous analysis of cost and sizing with the use of a recent optimization algorithm. The differences and restrictions of L-shaped reinforced concrete retaining wall design than classical T-shaped walls have been also discussed. The foundation width and the thickness of the wall required for a safe design has been also investigated according to the change of excavation depth, the type of soil dominating field and the external loading conditions. The observed results from optimization analyses shows that the variation of the shear strength angle is the most significant soil geotechnical parameter for supplying an envisaged safe design against sliding, overturning and adequate bearing capacity. Concurrently, the excavation depth is the most important factor that is forming the necessity of the construction of the retaining structure and optimal dimension evaluation. It is also proved that the wall foundation width is the most effected dimension of the retaining structures by the change of design parameters and the cost difference is directly influenced by the change of sizing. A cost-effective wall design can be performed with the use of proposed optimization analysis is capable in a shorter time than the traditional methods. Eventually, it has shown that such optimization methods may be useful to find the optimal design requirements for geotechnical engineering structures.

The Plan of the Saxon Shore Fort at Richborough

Recent excavation and coring of the collapsed east wall of the Saxon Shore fort of Richborough has revealed the manner in which the wall collapsed. This led to a re-evaluation of the original siting of the wall, which must have lain to the west of where it is usually depicted. Reassessment of previous excavations, including the examination of original records from the J.P. Bushe-Fox excavations of the 1920s and 1930s leads to the conclusion that the so-called ‘unfinished’ or ‘abandoned’ east wall foundation was in fact the base of the built east wall, from which the collapse derives. A revised fort plan based upon this conclusion is suggested. Supplementary material is available online (https://doi.org/10.1017/S0068113X20000379), and includes additional backing tables and illustrations referenced in the text.

Research on Treatment of Retaining Wall Foundation with Geosynthetics Based on BP Neural Network

Through the long-term load creep test of CE131 geonet and SD L25 retaining wall foundation, which are widely used in reinforced earth engineering, a large number of experimental data are obtained. On this basis, the least-squares and BP neural network are used to predict its creep variables. The principle of least squares is to find a curve in the curve family to fit the experimental data. From the sum of the squared errors σ = 0. 001 16, the fitting accuracy is higher. The BP neural network has adaptive learning and memory capabilities, especially the three-layer BP neural network model. The maximum error between the predicted value and the actual value is 0.91%, which is a lot better than the error of the least square 3.4%. This method Found a new way for creep prediction.

Sensitivity Assessment using Genetic Algorithm for Optimal Design of RC Ring Wall Foundation of Liquid Storage Tanks

Hydrocarbons and chemical industries extensively use storage tanks made of steel for storing large quantities of liquids. These tanks are typically supported on a RC ring wall foundation. This paper presents a method to minimize the cost of RC Ring Wall Foundations and study the sensitivity of this cost towards the different design parameters. The optimization process is developed through the use of genetic algorithm which simulates the biological evolution for the fittest (optimized) organism Previous studies on use of genetic algorithm in structural engineering has been applied to different structures like frames beams, columns etc. This paper extends the use of genetic algorithm to ring wall foundations of liquid storage tanks. The objective function for optimization includes the costs of concrete, steel, formwork and excavation whose sensitivity is analysed for parameters like grade of steel, concrete, seismic and wind loading for different tank sizes. All the constraints functions are set to meet the design requirements as per Indian Standard Codes and construction industry practices. Eight cases of parametric study are considered in order to illustrate the applicability of the genetic algorithm design model. It is concluded that this approach is economically more effective compared to conventional methods for design and sensitivities of different design parameters can be quickly assessed. Additionally this design methodology can be extended to deal with other types of structures as well