Halcrow Group Limited was a multinational engineering consultancy company, based in the United KingdomHalcrow was one of the UK's largest consultancies, with origins stretching back to 1868. The UK-based consultancy specialised in the provision of planning, design and management services for infrastructure development worldwide. With interests in transportation, water, maritime and property, the company undertook commissions in over 70 countries from a network of more than 90 offices.In 2011, the company was acquired by US firm CH2M Hill, and in 2013 it was announced that the Halcrow brand would eventually be discontinued. The parent subsequently (2015) rebranded the whole group to CH2M. Two years later, in December 2017, CH2M was acquired by Jacobs Engineering Group.
The response of an architectural glazing panel to dynamic loading, such as that from explosions, is analysed using an explicit dynamic finite element algorithm coded into a computer program. This software allows for the simulation of various glazing types, and is capable of predicting displacements and stresses up to cracking of the glass and the hazard level experienced by occupants. A variety of support conditions are available, along with several methods of specifying the blast load. Details and challenges of the numerical algorithm and coding are presented, together with the verification procedure that was performed through comparisons with results from analyses using general-purpose finite element programs and from available literature. In parallel, experimentation was performed to determine the dynamic mechanical properties of glass by testing the material in a Split Hopkinson Pressure Bar.
The behaviour of cast-iron bolted tunnels in London underground railway network was investigated using the 3-D finite element (FE) method. A series of numerical simulations on a cast-iron segmental ring were conducted and its performance was compared against the analytical assessment used by London Underground Limited (LUL). Unlike the 2D plane model used in the LUL standard, the proposed FE model considered the 3D lining structural features (i.e. the geometry of the tunnel segment and the bolted joint) in a detailed manner. The behaviour of a cast-iron tunnel primarily goes through three stages: tunnel construction, soil loading and structural deterioration. At each stage, the influences on the tunnel behaviour such as external loading, soil-tunnel interaction were examined. Considering that, the proposed model thus resulted in more realistically structural performance in agreement with the field measurements. (C) 2015 Elsevier Ltd. All rights reserved.
The behaviour of cast-iron tunnel segments used in London Underground tunnels was investigated using the 3-D finite element (FE) method. A numerical model of the structural details of cast-iron segmental joints such as bolts, panel and flanges was developed and its performance was validated against a set of full-scale tests. Using the verified model, the influence of structural features such as caulking groove and bolt pretension was examined for both rotational and shear loading conditions. Since such detailed modelling of bolts increases the computational time when a full scale segmental tunnel is analysed, it is proposed to replace the bolt model to a set of spring models. The parameters for the bolt-spring models, which consider the geometry and material properties of the bolt, are proposed. The performance of the combined bolt-spring and solid segmental models are evaluated against a more conventional shell-spring model. (C) 2014 Elsevier Ltd. All rights reserved.
Recent advancement in distributed fiber-optic sensing offers new possibilities for performance monitoring in the field of geotechnical and civil engineering. Brillouin optical time-domain reflectometry (BOTDR) is a commercially available technology that allows distributed strain measurements in the microstrain range along the full length of an optical fiber. By integrating a single fiber-optic cable into soil or a structure, an unprecedented amount of reasonably accurate (+/- 30 mu epsilon), spatially resolved data could be obtained. Since the BOTDR data is influenced by both strain and temperature, it is important that methods to separate the two effects are fully understood. This paper describes the BOTDR temperature compensation method by implementing appropriate thermal expansion coefficients of optical cables and structures to the raw data. In the laboratory study, validation of the instrumentation technique was conducted in a concrete beam by embedding two types of optical cables consisting of tight-buffered and loose-tubed coatings to measure thermal strains response during concrete curing. Temperature readings inferred from optical fibers were found to be in accordance to the thermocouples. A field study of axially loaded concrete pile subjected to cooling and heating cycle is presented. Measurements in the test pile and adjacent borehole indicate similar strain profiles and temperature changes between BOTDR and conventional instrumentation such as vibrating wire strain gauges and thermistors. General steps to derive the temperature compensated strain profiles observed in the thermal pile as a result of cooling and heating is presented. The data enables load-transfer profiles to be interpreted and used as framework to understand pile response to temperature changes.
