Modelling effects of axial load on behaviour of pile groups in laterally-spreading soil

Previous research into the behaviour of piled foundations in laterally-spreading soil deposits has concentrated on pile groups that carry small or negligible axial loads. This paper presents dynamic centrifuge test results for 2 x 2 pile groups with bending and geometric properties similar to real 0.5 m diameter tubular steel and solid circular reinforced-concrete field piles. Axial loads applied represented upper-bounds on typical working loads. The simultaneous scaling of the relevant properties controlling both lateral and axial behaviour allows comparisons to be drawn regarding the particular mechanisms of failure that would dominate for each type of pile. Flexible reinforced-concrete piles which tend to carry lower loads were found to be dominated by lateral effects, while steel piles, which are much stiffer and usually carry greater loads are dominated by settlement considerations. © 2006 Taylor & Francis Group.

The response of buildings to tunnelling: A case study

A case study of the response of two buildings to the construction of a 12 m diameter tunnel excavated by conventional method, in Italy, is studied. The 12 m diameter tunnel was constructed carrying out reinforcement of the tunnel face and around the crown prior to excavation and installation of the temporary sprayed concrete lining and the permanent reinforced concrete lining. Reflective prisms, placed at first floor level around the perimeter of the building facades, allowed building settlements to be measured. Ground settlements between the two buildings were measured using BRE type settlement studs. Extensive protective measures were adopted to maintain stability of the tunnel excavation and to reduce ground movements. The number of horizontal jet grout columns installed into the tunnel face was reduced over the course of the project. Results from CPT tests indicate that the undrained shear strength at the tunnel axis is around 120 kPa. SPT and undrained unconsolidated (UU) triaxial tests indicate lower strengths of around 80 kPa, although this may be due to sample disturbance.

Modelling effects of axial load on behaviour of pile groups in laterally-spreading soil

Previous research into the behaviour of piled foundations in laterally-spreading soil deposits has concentrated on pile groups that carry small or negligible axial loads. This paper presents dynamic centrifuge test results for 2×2 pile groups with bending and geometric properties similar to real 0.5m diameter tubular steel and solid circular reinforced-concrete field piles. Axial loads applied represented upper-bounds on typical working loads. The simultaneous scaling of the relevant properties controlling both lateral and axial behaviour allows comparisons to be drawn regarding the particular mechanisms of failure that would dominate for each type of pile. Flexible reinforced-concrete piles which tend to carry lower loads were found to be dominated by lateral effects, while steel piles, which are much stiffer and usually carry greater loads are dominated by settlement considerations. © 2006 Taylor & Francis Group, London.

Generating the Sparse Point Cloud of a Civil Infrastructure Scene Using a Single Video Camera under Practical Constraints

Automating the model generation process of infrastructure can substantially reduce the modeling time and cost. This paper presents a method to generate a sparse point cloud of an infrastructure scene using a single video camera under practical constraints. It is the first step towards establishing an automatic framework for object-oriented as-built modeling. Motion blur and key frame selection criteria are considered. Structure from motion and bundle adjustment are explored. The method is demonstrated in a case study where the scene of a reinforced concrete bridge is videotaped, reconstructed, and metrically validated. The result indicates the applicability, efficiency, and accuracy of the proposed method.

Closely correlating lower and upper bound plastic analysis of real slabs

An engineer assessing the load-carrying capacity of an existing reinforced concrete slab is likely to use elastic analysis to check the load at which the structure might be expected to fail in flexure or in shear. In practice, many reinforced concrete slabs are highly ductile in flexure, so an elastic analysis greatly underestimates the loads at which they fail in this mode. The use of conservative elastic analysis has led engineers to incorrectly condemn many slabs and therefore to specify unnecessary and wasteful flexural strengthening or replacement. The lower bound theorem is based on the same principles as the upper bound theorem used in yield line analysis, but any solution that rigorously satisfies the lower bound theorem is guaranteed to be a safe underestimate of the collapse load. Jackson presented a rigorous lower bound method that obtains very accurate results for complex real slabs.

Static response of UHPFRCC slab specimens

The aim of this study is to present the results of an extended work on the development of an Ultra High Performance Fibre Reinforced Cementitious Composite (UHPFRC) and the experimental determination of the mechanical properties of the produced material. Furthermore, the paper will present preliminary experimental results on the static response of Reinforced Concrete and UHPFRCC slab specimens.

Mix design, mechanical properties and impact resistance of UHPFRCCs

The research work focused on the determination of guidelines for the production of an UHPFRCC, and the experimental investigation of the quality and the behaviour of this material in a highly demanding application, such as the impact resistance of structures. Specifically, the aim of this study is to present the results of an extended work on the development of an UHPFRCC and the experimental determination of the mechanical properties of the produced material. Furthermore, the paper will present preliminary experimental results on the impact resistance of Reinforced Concrete and UHPFRCC slab specimens. © 2012 Taylor & Francis Group.

Experimental behaviour of barrel vaulted structure subjected to rocking of the abutments

In this paper, the transverse rocking mechanism of a barrel vaulted structure subjected to horizontal cyclic loads is analysed by means of experimental tests on full scale model and by means of non-linear FE analyses. The study is part of an ongoing experimental and theoretical research program, developed by the University of Brescia, concerning the seismic behaviour of ancient masonry buildings. The scope of the paper is to provide some evidence of the rocking mechanism experienced by barrel vaulted structures under horizontal loading. The understanding of the behaviour of these structural systems is necessary for their seismic vulnerability assessment, as well as for the correct design of possible strengthening techniques. A numeric FE model was validated through comparison with the experimental results and it was used to verify the efficiency of two common strengthening solutions: the technique of the overlaying reinforced concrete slab and the technique of the thin spandrel walls. Experimental and numeric results will be discussed in the paper.