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Detection of damage to structures has recently received considerable attention from the viewpoint of maintenance and safety assessment. In this respect, the vibration characteristics of buildings have been applied consistently to obtain a damage index of the whole building, but it has not been established as a practical method until now. It is reasoned that this is perhaps due to restrictions on the experiment, use of improper method, and lack of inspection opportunity for the structures. In addition, in the case of large‐scale structures such as buildings, many variables to be considered for the analysis contribute to a large number of degrees of freedom, and this can also be a considerable problem for the analysis. A practical method for the detection of structural damage using the first natural frequency and mode shape of building is proposed in this paper. The effectiveness of the proposed method is verified by numerical analysis and experimental tests. From the results, it is observed that the severity and location of the damage can be estimated with a relatively small error by using modal properties of building. Copyright © 2004 John Wiley & Sons, Ltd.

Summary Concrete‐filled steel tubular (CFST) arch bridges have been widely used in mainland China, and their systematic safety evaluation has gained increasing attention from the bridge authorities in recent years. This paper presents the framework and application of Level 2 safety evaluation of CFST arch bridges, incorporating structural health monitoring (SHM) and inspection information. In contrast with the traditional inspection‐based qualitative assessment and direct measurement‐based quantitative assessment for SHM, Level 2 safety evaluation considers the inevitable resistance deterioration and site‐specific loading under normal operation conditions. For such safety evaluations, the most important element is using the well‐established finite element modelling for representing the actual conditions as accurately as possible. Thus, in this study, component and global finite element model (FEM) updating techniques are employed to ensure the local and global behaviour of the updated FEM, through which several types of common CFST arch bridge defects are investigated and updated. Measured site‐specific live loads experienced by CFST arch bridges are considered and transformed into design loads for comparison. Unfavourable load patterns are applied to the updated FEM for structural reanalysis, to evaluate the component safety status, and gradually increasing unfavourable load patterns are applied to the FEM to perform an ultimate load‐bearing analysis to obtain the global safety reservation. Level 2 safety evaluation is conducted by considering modal parameters, displacements, fatigue damage, and component and global safety status. Level 2 safety evaluation is applied to a typical CFST arch bridge, to demonstrate the entire evaluation process and the effectiveness of the proposed safety evaluation framework.

This paper presents the experimental results of four full-scale coupling beams in which only horizontal reinforcements are placed, without diagonal reinforcements, with the aim to develop reinforcement details for coupling beams used in connecting side walls in a wall-slab structural system. Each coupling beam specimen was designed according to the deep-beam design procedure that does not use diagonal reinforcements and that is found in current standards. Two cases for basic deep-beam design specimens were investigated wherein (1) U-type reinforcement was added to prevent sliding shear failure of the joints and (2) horizontal intermediate reinforcements were placed. The coupling beam specimens were fabricated with a shear span-to-depth ratio (aspect ratio) of 1.68 and were connected to walls only by horizontal reinforcements, i.e., without diagonal reinforcement. The experimental results indicate that the strength of the beams was about 1.5 times the designed strength of a strut-and-tie model, which suggests that the model is available for predicting the strength of coupling beams with conventional reinforcement layouts such as horizontal and transverse reinforcement bars. The deformation capacity of these conventionally reinforced concrete coupling beams ranged from 1.48 to 3.47% in accordance with the reinforcement layouts of the beams. Therefore, this study found that the performance of conventionally reinforced concrete coupling beams with an aspect ratio of 1.68 can be controlled through the implementation of reinforcement details that include U-type reinforcement and the anchorage of intermediate horizontal bars.

This study investigates how firms invest in building and maintaining business–government (B–G) ties when they aim to innovate in regions where, due to institutional transitions, institutional contexts differ remarkably. Using data from the China Enterprise Survey of the World Bank, empirical findings suggest that the influence of B–G ties on Chinese firms’ product innovation is different in distinctive institutional contexts in China. More specifically, during institutional transition, B–G ties become less efficient for facilitating product innovation when regional legal institutions and infrastructural supporting systems in a region are more stable, fair, and efficient. By contrast, during institutional transition, a positive effect of B–G ties on firm product innovation in a region becomes more significant when financial systems are relatively advanced. In addition to this, the value of B–G ties for firm product innovation appears to be more stable when business regulation develops within subnational regions.

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