Test Level 4 Bridge Rails

Author(s):  
C. Eugene Buth ◽  
Wanda L. Menges ◽  
William F. Williams

Design details and full-scale crash test results are presented for three bridge rails tested for compliance with NCHRP Report 350 Test Level 4 requirements. Designs of these rails are based on AASHTO LRFD Bridge Design Specifications. Each bridge rail consists of structural steel tubing rail elements mounted on wide-flange posts. The rails are generally stronger than many designs commonly used in the recent past. Full-scale crash test results demonstrated that all bridge rails meet NCHRP Report 350 safety performance requirements.

Author(s):  
John F. Carney ◽  
Charles E. Dougan ◽  
Eric C. Lohrey

The results of four full-scale crash tests performed on the Connecticut Truck Mounted Attenuator (CTMA) are summarized. The tests were conducted in accordance with the guidelines of NCHRP Report 350 for Test Level 2 devices. NCHRP Report 350 specifies two required and two optional tests. The four crash tests passed all requirements of NCHRP Report 350. No repeat tests were required, and the results were uniformly excellent. The successful CTMA test series is the first of several NCHRP Report 350 test programs that are anticipated to gain compliance for various impact attenuation systems designed and developed in Connecticut.


Author(s):  
C. Eugene Buth ◽  
Wanda L. Menges ◽  
King K. Mak ◽  
Roger P. Bligh

Three guardrail-to-bridge rail transitions were developed and subjected to full-scale crash tests. The transitions were ( a) a nested W-beam with W-beam rub rail that transitioned from a W-beam guardrail to a vertical concrete parapet bridge rail, ( b) a nested thrie-beam that transitioned from a W-beam guardrail to a tubular steel bridge rail, and ( c) a tubular steel transition that transitioned from a weak-post box-beam guardrail to a tubular steel bridge rail. The nested W-beam and the tubular steel transitions were tested and met NCHRP Report 350 Test Level (TL)-3 requirements. The nested thrie-beam transition was tested and met TL-4 requirements.


Author(s):  
Scott K. Rosenbaugh ◽  
Ronald K. Faller ◽  
Jennifer D. Schmidt ◽  
Robert W. Bielenberg

Roadway resurfacing and overlay projects effectively reduce the height of roadside barriers placed adjacent to the roadway, which can negatively affect their crashworthiness. More recently, bridge rails and concrete barriers have been installed with slightly increased heights to account for future overlays. However, adjacent guardrails and approach transitions have not yet been modified to account for overlays. The objective of this project was to develop an increased-height approach guardrail transition (AGT) to be crashworthy both before and after roadway overlays of up to 3 in. The 34-in. tall, thrie-beam transition detailed here was designed such that the system would be at its nominal 31-in. height following a 3-in. roadway overlay. Additionally, the upstream end of the AGT incorporated a symmetric W-to-thrie transition segment that would be replaced by an asymmetric transition segment after an overlay to keep the W-beam guardrail upstream from the transition at its nominal 31-in. height. The 34-in. tall AGT was connected to a modified version of the standardized buttress to mitigate the risk of vehicle snag below the rail. The barrier system was evaluated through two full-scale crash tests in accordance with Test Level 3 (TL-3) of AASHTO’s Manual for Assessing Safety Hardware (MASH) and satisfied all safety performance criteria. Thus, the 34-in. tall AGT with modified transition buttress was determined to be crashworthy to MASH TL-3 standards. Finally, implementation guidance was provided for the 34-in. tall AGT and its crashworthy variations.


Author(s):  
Malcolm H. Ray

A method of comparing two acceleration time histories to determine whether they describe similar physical events is described. The method can be used to assess the repeatability of full-scale crash tests and it can also be used as a criterion for assessing how well a finite-element analysis of a collision event simulates a corresponding full-scale crash test. The method is used to compare a series of six identical crash tests and then is used to compare several finite-element analyses with full-scale crash test results.


Author(s):  
Chuck A. Plaxico ◽  
Malcolm H. Ray ◽  
Kamarajugadda Hiranmayee

Several types of strong-post W-beam guardrails are used in the United States. Usually the only difference between one type of strong-post W-beam guardrail and another is the choice of post and block-out types. The impact performance of two very similar strong-post W-beam guardrails are compared—the G4(2W), which uses a 150×200 mm wood post and the G4(1W), which uses a 200×200 mm wood post. Although G4(2W) is used in numerous states, G4(1W) is now common only in the state of Iowa. The performance of the two guardrails has been presumed equal, but only one full-scale crash test has been performed on G4(1W) and that was over 30 years ago, using a now-obsolete test vehicle. The nonlinear finite element analysis program LS-DYNA was used to evaluate the crashworthiness of the two guardrails. The G4(2W) guardrail model was validated with the results of a full-scale crash test. A model of the G4(1W) guardrail system was developed, and the deflection, vehicle redirection, and occupant risk factors of the two guardrails were compared. The impact performance of the two guardrails was quantitatively compared using standard techniques. The analysis results indicate similar collision performance for G4(1W) and G4(2W) and show that both satisfy NCHRP Report 350 Test 3-11 safety performance requirements.


Author(s):  
Ronald K. Faller ◽  
Ketil Soyland ◽  
Dean L. Sicking

An approach guardrail transition for use with the single-slope concrete median barrier was developed and crash tested. The transition was constructed with 3.43-mm-thick (10-gauge) thrie-beam rail and was supported by nine W6 × 9 steel posts. Post spacings consisted of one at 292 mm (11.5 in.), five at 476 mm (1 ft 6.75 in.), and three at 952 mm (3 ft 1.5 in.). A structural tube spacer block (TS 7 × 4 × 3/16) was also developed for use with the thrie-beam rail. Two full-scale vehicle crash tests were performed, and the system was shown to meet the Test Level 3 requirements specified in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features.


2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Abbas AbdulMajeed Allawi

The use of external posttensioning technique for strengthening reinforced concrete girders has been considerably studied by many researchers worldwide. However, no available data are seen regarding strengthening full-scale composite prestressed concrete girders with external posttensioned technique under static and repeated loading. In this research, four full-scale composite prestressed I-shape girders of 16 m span were fabricated and tested under static and repeated loading up to failure. Accordingly, two girders were externally strengthened with posttensioned strands, while the other two girders were left without strengthening. The experimental tests include deflection, cracking load, ultimate strength and strains at midspan, and loading stages. Test results were compared with the design expressions mentioned in AASHTO LRFD specifications and ACI 318-2014 code. Also, a nonlinear analysis was conducted using the finite element method (FEM). The presented analysis models were verified by comparing the model results with test results. The general theme abstracted from both experimental tests and numerical analysis reflects that the performance and procedure of strengthening with external prestressing of girders were found to be effective in increasing the load carrying capacity of the strengthened girders.


Author(s):  
Jennifer D. Schmidt ◽  
John D. Reid ◽  
Nicholas A. Weiland ◽  
Ronald K. Faller

The recommended minimum length for the standard Midwest Guardrail System (MGS) is 175 ft (55.3 m) based on crash testing according to NCHRP Report 350 and AASHTO's Manual for Assessing Safety Hardware (MASH) specifications. However, varying roadside hazards and roadway geometries may require a W-beam guardrail system to be shorter than the currently tested minimum length. The effects of reducing system length for the MGS were therefore investigated. The research study included one full-scale crash test with a Dodge Ram pickup truck striking a 75-ft (22.9-m) long MGS system. The barrier system satisfied all MASH Test Level 3 (TL-3) evaluation criteria for Test Designation Number 3-11. Test results confirmed that the reduced system length did not adversely affect overall system performance or deflections. Simulations that used BARRIER VII and LS-DYNA were also conducted to analyze system performance with reduced lengths of 50 ft (15.2 m) and 62 ft 6 in. (19.1 m). Both system lengths exhibited the potential for successfully redirecting an errant vehicle at MASH TL-3 test conditions. However, these reduced-length systems would have a narrow window for redirecting vehicles and would be able to shield hazards of only a limited size. Owing to limitations associated with the computer simulations, full-scale crash testing is recommended before these shorter systems are installed.


Author(s):  
Mario Mongiardini ◽  
Ronald K. Faller ◽  
John D. Reid ◽  
Dean L. Sicking

Most state departments of transportation use simple adaptations of crashworthy guardrail end terminals, which typically include breakaway posts and an anchor cable, for downstream anchorage systems. The guardrail safety performance for vehicular impacts occurring in close proximity to these simplified, downstream anchorage systems is not well known. Further, the length of need (LON) for the downstream end of these systems has yet to be adequately determined. This research project assessed the safety performance of the Midwest Guardrail System (MGS) for impacts occurring in close proximity to a nonproprietary, trailing-end guardrail terminal under the Test Level 3 conditions of the Manual for Assessing Safety Hardware. The two research objectives were to (a) determine the end of the LON for impacts with light pickup trucks and (b) investigate potential risks for a small passenger car to become unstable when striking the downstream end of the MGS anchored by the nonproprietary, trailing-end terminal. Numerical simulations were carried out to identify the most critical impact location for the 1100C small car and the end of the LON for the 2270P pickup truck. In full-scale crash tests, considerable snag of the 1100C vehicle occurred; however, occupant risk values and vehicle stability were within acceptable limits. The crash test with the 2270P pickup indicated that the end of the LON was located at the sixth post from the downstream-end post. Guidelines were proposed for installing the MGS to shield hazards in close proximity to the tested nonproprietary, trailing-end terminal.


Author(s):  
Scott K. Rosenbaugh ◽  
Jennifer D. Schmidt ◽  
Harald P. Larsen ◽  
Ronald K. Faller ◽  
Andrew Pankratz

This project in Manitoba, Canada, developed a single-slope concrete barrier system with a height of 1,250 mm and a base width of no more than 600 mm. Configurations for bridge rail, roadside, and median barrier applications were developed and optimized to minimize installation costs while satisfying the AASHTO Manual for Assessing Safety Hardware (MASH) Test Level 5 performance standards. Additionally, a bridge deck was developed for the overhang portion of the deck supporting the bridge rail. To evaluate the new barrier system, a 45.7-m-long section of the bridge rail was constructed on a simulated bridge deck and subjected to a full-scale crash test according to MASH Test 5-12. During the test, the 36,000-kg vehicle was safely redirected with minimal roll to the cab and trailer. Damage to the barrier and deck was minor, consisting of concrete gouging, hairline cracks, and some spalling to the top of the barrier. Thus, the Manitoba constrained width tall wall was deemed crashworthy to MASH Test Level 5 standards.


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