Vehicle Bump Testing Parameters Influencing Modal Identification of Long-Span Segmental Prestressed Concrete Bridges.

Wilson Hernandez,Carlos Alberto Riveros-Jerez,Alvaro Viviescas

doi:10.3390/s22031219

Abstract

In-service prestressed concrete box girder bridges have received increasing attention in recent years due to a large number of bridges reaching decades in service. Therefore, the ageing of infrastructure demands the development of robust condition assessment methodologies based on affordable technology such as vehicle-induced vibration tests (VITs) in contrast with more expensive existing technologies such as tests using hammers or shakers. Ambient vibration tests (AVTs) have been widely used worldwide, taking advantage of freely available ambient excitation sources. However, the literature has commonly reported insufficient input energy to excite the structure to obtain satisfactory modal identification results, especially in long-span concrete bridges. On the other hand, the use of forced vibration tests (FVTs) requires more economic resources. This paper presents the results of field measurements at optimally selected locations in VITs consisting of a 32-ton truck and a springboard with a height of 50 mm. AVTs using optimal sensor placement (OSP) provide similar results to VITs without considering OSP locations. Additionally, the VIT/AVT cost ratio is reduced to 2 since a shorter data collection time is achieved within a one-day (8 h) test framework, which minimizes temperature effects, thus leading to improvements in AVT identification results, especially in vertical modes.

Highlights

Existing prestressed concrete (PC) segmentally constructed bridges have received increasing attention in recent years due to a considerable number of in-service bridges that have suffered from excessive mid-span deflection, restricting the construction of PC bridges with larger spans [1]
Ye et al [1] successfully separate the effects of live load, temperature, and structural deflection from deflection signals obtained from numerical models up to noise levels of 10%, field validation was greatly affected by environmental factors
An adequate preliminary analysis based on finite element (FE) models is essential to identify the most critical parameters to be considered in field tests

Summary

Introduction

Existing prestressed concrete (PC) segmentally constructed bridges have received increasing attention in recent years due to a considerable number of in-service bridges that have suffered from excessive mid-span deflection, restricting the construction of PC bridges with larger spans [1]. The ageing of in-service bridges and the construction of bridges with longer spans demand the development of non-destructive test (NDT) methods for structural condition assessment to ensure safe operation by considering structural degradation and environmental factors. The variation of modal parameters is related to changes in physical properties of a bridge, and field studies have shown that environmental and operational factors, such as temperature, traffic, humidity, and solar radiation, induce changes in modal parameters commonly used in vibration-based damage detection methods, temperature variation is the critical source of modal variability. Changes in modal frequencies caused by temperature variation may reach 10%, showing values higher than those related to changes in modal frequencies due to structural degradation.

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