Abstract. This paper provides a critical overview of available technology and facilities for determining human-induced dynamic forces of civil engineering structures, such as due to walking, running, jumping and bouncing. In addition to traditional equipment for direct force measurements comprising force plate(s), foot pressure insoles and instrumented treadmills, the review also investigates possibility of using optical motion tracking systems (marker-based and marker-free optoelectronic technology) and non-optical motion tracking systems (inertial sensors) to reproduce contact forces between humans and structures based on body kinematics data and known body mass distribution. Although significant technological advancements have been made in the last decade, the literature survey showed that the state-of-the-art force measurements are often limited to individuals in artificial laboratory environments. Experimental identification of seriously needed group-and crowd-induced force data recorded on as-built structures, such as footbridges, grandstands and floors, still remains a challenge due to the complexity of human actions and the lack of adequate equipment.

Structural health monitoring is a useful tool for evaluating the condition of bridges, with permanent systems installed on bridges which form vital links on the major transport network. The economic cost of the monitoring systems limits their installation on smaller bridges which make up the wider transport network. A short-term monitoring system can be quickly installed and adjusted to suit the requirements of individual bridges. These systems are ideal for rural regions with a high number of single span bridges on isolated road and rail networks. This report will review a single span bridge on a private heritage railway under loading from passing steam engines, including the Flying Scotsman. Acceleration data are used to determine the rotations and deflections of the bridge deck. To verify the data, deflection measurements at mid-span were recorded using a video-based measurement system. The deflection measurements from the accelerometers correlate with the video imagery measurements.

Maintaining offshore steel structures is challenging and not environmentally friendly due to the frequent visits for inspection and repairs. Some offshore lighthouses are equipped with carbon steel helidecks fixed onto their lantern galleries in the 1970s to provide easy and safe access to maintenance staff and inspectors. Even though the helidecks supporting structures have maintained their integrity and are still functional in the offshore harsh environmental conditions, their inspection and maintenance remains a challenge due to the need of frequent visits which requires flying to the location of the lighthouse to bring the maintenance staff and equipment. We have developed a multidisciplinary computational framework to design new generation of aluminium helidecks for offshore lighthouses. We calculated the wind speed at the location of the Bishop Rock lighthouse based on the meteorological data, and the load distribution on the helideck due to such a wind condition, using computational fluid dynamic analysis. Then, we used the calculated wind load with other mechanical loads in the events of normal and emergency landings of a helicopter on this structure to find the best design configuration for this helideck. We generated a design space for different configurations of a beam structure and carried out, static, transient and buckling analysis to assess each case using finite element method. The selection criterion was set to find the structure with the minimum volume fraction and compliance while keeping the stress below the allowable stress. We found the structure with eight vertical and circumferential sections featuring two rows of diagonal bracing with one at the base and the other one at the third section from the base of the helideck was the optimum design for the considered loading in this work. This framework can be adopted for the design and optimisation of other offshore structures by other researchers and designers.

The team from Bristol University have demonstrated that ambient vibration tests can be used to determine the natural frequencies and mode shapes of the lowest frequency modes of vibration of long span suspension bridges and so check the values used in design.120. Although not mentioned in the Paper, a three-man team from the Building Research Establishment (BRE) also carried out ambient vibration tests on the Humber Bridge at the same time as the team from Bristol University. The BRE approach was slightly different in that signals from thirteen accelerometers were recorded simultaneously for about twelve hours. These thirteen accelerometers were positioned throughout one-half of the bridge to measure vertical motion, and a recording made. The accelerometers were then re-oriented and two further recordings made, one to measure lateral motion and the other to measure torsional motion. The accelerometers were then moved to the other half of the bridge and the process repeated. This enabled the vertical, lateral and torsional motion of the whole bridge to be obtained from just six recordings. However, the results obtained for the natural frequencies and mode shapes of the bridge are in good agreement with those presented in the Paper, particularly for the vertical modes where the results are almost identical." 121. The main reason for using the longest practical recording time was to try to minimize lack of frequency resolution in the analysis: a problem referred to in Appendix 2 of the Paper. The extremely low natural frequencies of long span suspension bridges, coupled with low damping values, can lead to enormous bias errors in the spectral analysis. Indeed, for any of the ambient vibration tests conducted on long span suspension bridges, if the damping values for all the mainspan deck modes are plotted against frequency, a characteristically shaped curve occurs. Figs 14 and 15 show this for the tests by Bristol University on the Humber Bridge and for the tests carried out on the Golden Gate Bridge.4 The lower the natural frequencies of a bridge, the more pronounced is the increase in apparent damping, so the results from shorter span bridges with higher natural frequencies show a similar but less pronounced curve. This phenomenon can be explained as the bias errors in the spectral analysis swamping the true values, in which case, these curves would not represent real damping values. The results of the 1985 tests by BRE also suffer from the same phen~menon,'~ although they

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