Assessment of Bridges Subjected to Vehicular Collision

Vehicles often collide with bridges. However, there are no available guidelines for bridge inspectors to assess damage and to make repair decisions. This project addresses this gap by investigating the behavior of steel girder bridges subjected to vehicular collision through (1) performing non-destructive field testing, (2) developing validated numerical models, and (3) performing parametric investigations to extend research findings. Field testing was performed using Digital Image Correlation (DIC) - a portable, non-destructive, photographic measurement technique. The focus was on two- and three-span continuous multi-girder steel bridges for which an exterior girder has sustained Category T damage, i.e., torsion about the longitudinal direction. This project can benefit Indiana Department of Transportation (INDOT) business processes by potentially reducing the number or amount of repairs, leading to cost savings and longer lifespans for bridges

A Novel Test Rig for the Basic Nonlinear Characterization of Bolted Joints

The paper aims at performing a comprehensive experimental study on the peculiar properties of a bolted joint, and investigates the damping induced at different interfaces (between flanges, bolt head/nut and flange, threads) during vibrations. A novel, simplified, single-bolt system joining a two-beam structure is designed and tested. Experimental results under different boundary conditions are presented, and the influence of the harmonic excitation force, as well as the bolt tension, is investigated. The test results show how the contact interface between the clamped flanges plays an important role in terms of frictional damping provided to the system during vibration, while the contact interfaces between the head/nut and flange, and secondarily between the threads, affect the system response at a less, but not negligible, extent. The test setup and test procedure can provide a database to validate single bolt contact models to be included in a more complex structure

Multiple shaking tables tests of seismic pounding effect of reinforced concrete bridge model

In order to investigate the longitudinal pounding effect of highway bridges with high-piers under strong ground motions, multiple shaking tables tests of a 1/10 scaled continuous rigid frame and simply-supported girder bridge with high-piers were carried out. The pounding responses of the bridge model under different earthquake excitations including the uniform excitation and the traveling wave excitation were studied, and the effectiveness of the dampers and isolation bearings for reducing the seismic pounding effect were analyzed and discussed. Test results indicate that the traveling wave effect is the important factor in seismic pounding response of high pier bridges. Additional dampers can mitigate the pounding effect apparently and play a role in reducing seismic response for bridge superstructures. Compared with conventional rubber bearing (RB), the decreases in the relative displacement and the pounding force between adjacent girders were 30 % and 55 % with lead rubber bearing (LRB) in this experiment, respectively. Seismic pounding effect of bridge superstructures depends on different structural dynamic properties of adjacent girders and characteristics of ground motions

Formulating a Strategy for Securing High-Speed Rail in the United States, Research Report 12-03

This report presents an analysis of information relating to attacks, attempted attacks, and plots against high-speed rail (HSR) systems. It draws upon empirical data from MTI’s Database of Terrorist and Serious Criminal Attacks Against Public Surface Transportation and from reviews of selected HSR systems, including onsite observations. The report also examines the history of safety accidents and other HSR incidents that resulted in fatalities, injuries, or extensive asset damage to examine the inherent vulnerabilities (and strengths) of HSR systems and how these might affect the consequences of terrorist attacks. The study is divided into three parts: (1) an examination of security principles and measures; (2) an empirical examination of 33 attacks against HSR targets and a comparison of attacks against HSR targets with those against non-HSR targets; and (3) an examination of 73 safety incidents on 12 HRS systems. The purpose of this study is to develop an overall strategy for HSR security and to identify measures that could be applied to HSR systems currently under development in the United States. It is hoped that the report will provide useful guidance to both governmental authorities and transportation operators of current and future HSR systems

Sustainable Design of Belmont Street/Route 9 Bridge

Based on inspection reports provided by MassHighway, the Belmont Street/Route 9 Bridge has three bridge components deemed deficient . The deck slab, girders, and columns were re-designed using AASHTO specifications and LRFD design. Additionally, sustainable bridge design aspects were examined including alternative building materials, maintenance protection, stormwater management, and transportation and urban planning. Lastly, a life-cycle cost analysis considering the re-designed bridge components and maintenance was conducted and a sustainable bridge guideline for future bridge design projects was created

SciTech News Volume 71, No. 1 (2017)

Columns and Reports From the Editor 3 Division News Science-Technology Division 5 Chemistry Division 8 Engineering Division Aerospace Section of the Engineering Division 9 Architecture, Building Engineering, Construction and Design Section of the Engineering Division 11 Reviews Sci-Tech Book News Reviews 12 Advertisements IEEE

Lightweight Vehicle Structures that Absorb and Direct Destructive Energy Away from the Occupants

One of the main thrusts in current automotive industry is the development of occupant-centric vehicle structures that make the vehicle safe for the occupants. A design philosophy that improves vehicle survivability by absorbing and redirecting destructive energy in underbody blast events should be developed and demonstrated. On the other hand, the size and weight of vehicles are also paramount design factors for the purpose of providing faster transportation, great fuel conservation, higher payload, and higher mobility. Therefore, developing a light weight vehicle structure that provides a balance between survivability and mobility technologies for both vehicle and its occupants becomes a design challenge in this research. One of the new concepts of absorbing blast energy is to utilize the properties of “softer” structural materials in combination with a damping mechanism for absorbing the destructive energy through deformation. These “softer” materials are able to reduce the shock loads by absorbing energy through higher deformation than that of characteristic of normal high strength materials. A generic V-hull structure with five bulkheads developed by the TARDEC is used in the study as the baseline numerical model for investigating this concept. Another new concept is to utilize anisotropic material properties to guide and redirect the destructive energy away from the occupants along pre-designated energy paths. The dynamic performance of multilayer structures is of great interest because they act as a mechanism to absorb and spread the energy from a blast load in the lateral direction instead of permitting it to enter occupant space. A reduced-order modeling (ROM) approach is developed and applied in the preliminary design for studying the dynamic characterization of multilayer structures. The reliability of the ROM is validated by a spectral finite element analysis (SFEA) and a classic finite element analysis by using the commercial code Nastran. A design optimization framework for the multilayer plate is also developed and used to minimize the injury probability, along with a maximum structural weight reduction. Therefore, the goal of designing a lightweight vehicle structure that has high levels of protection in underbody blast events can be achieved in an efficient way.PHDNaval Architecture & Marine EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/135895/1/leaduwin_1.pd

Dynamic response of highway bridges under a moving truck and development of a rational serviceability requirement

Through the development and usage of high-strength materials, the design of more flexible bridges is unavoidable. It is assumed that limiting a bridge static deflection would control the excessive vibration caused by more flexible design. However, results of prior studies indicate that deflection limits do not necessarily address bridges vibrational issue. This dissertation addresses the parameters affecting bridge vibration and provides simple equations to compute bridge dynamic acceleration, velocity and displacement in both transient and steady state parts of the vibration. These equations can then be used to control bridges excessive vibration; and provide human comfort and structural performance. A comprehensive analytical study was performed to evaluate dynamic response of bridges under a moving truck load. The effect of bridge dynamic parameters and vehicle moving conditions are investigated, which includes bridge frequency, damping ratio, span length, girders distance, bracing, support conditions, truck speed, load sequence, axle‘s weight, and number of spans. Bridge and vehicle k-parameters, which represent the number of vibration cycles before the next excitation occurs, are developed to better explain the vibrational behavior of a bridge. The proposed equations include bridge frequency, static deflection for one axle load, and k-parameters. Finally, a case study is presented to highlight the application of the new approach

Concrete Patching Materials and Techniques and Guidelines for Hot Weather Concreting

High early strength (HES) concrete is becoming increasingly used to repair damaged concrete pavement sections. The use of HES concrete enables the repaired pavement to be opened to traffic within hours of placing the concrete. Rapid repair of concrete pavement is an attractive solution since the traveling public is not delayed by the repair of the pavement in addition to a decrease in the amount of exposure to traffic by construction personnel; however, there are challenges due to strict requirements for opening strength and severe penalties for not achieving the target strength. This project examined failure to obtain long term strength in the construction practices of long patches in concrete pavements. The work examined issues associated with temperature on sulfate balance, flexural strength prediction (maturity methods) considering the influence of moisture (effects of self-desiccation), shrinkage mitigation techniques (internal curing), and improving the overall durability of HES concrete patching materials