Robert W Bielenberg

Midwest Guardrail System for Standard and Special Applications

Development, testing, and evaluation of the Midwest Guardrail System were continued from the original research started in 2000. This new strong-post W-beam guardrail system provides increased safety for impacts with higher-center-of-mass vehicles. Additional design variations of the new system included stiffened versions using reduced (half and quarter) post spacings as well as a standard guardrail design configured with a concrete curb 152 mm (6 in.) high. All full-scale vehicle crash tests were successfully performed in accordance with the Test Level 3 requirements specified in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. The research study also included dynamic bogie testing on steel posts placed at various embedment depths and computer simulation modeling with BARRIER VII to analyze and predict dynamic guardrail performance. Recommendations for the placement of the original Midwest Guardrail System as well as its stiffened variations were also made.

Detailed Tire Modeling for Crash Applications

Abstract In many crashworthiness applications the tire and suspension play a significant role in the behavior of the vehicle during the crash. For many of those applications, that role can be effectively modeled with simplified models of those parts. However, in some crash events the tire and suspension need to be modeled in great detail in order to accurately capture the response of the vehicle. To better simulate such events, a new tire model was developed that takes into account the major components of a tire, including the tread, sidewall, steel beads, steel belts and body plies. Laboratory testing was performed in order to help validate the tire model. LS-DYNA, a nonlinear finite element analysis code, was used as the simulation tool. Some important details about properly pressurizing the tire and using relative damping to control excessive tread vibrations were discovered during the research. A significant effort was made to keep the number of elements in the model as low as possible without sacrificing accuracy in order to keep computational costs down. The new tire model was used on several applications including impacting a curb, driving over rocks, and landing on a culvert grate to demonstrate its effectiveness.

Performance of Steel-Post, W-Beam Guardrail Systems

On the basis of the proposed changes to the NCHRP Report 350 guidelines, NCHRP Project 22-14(2) researchers deemed it appropriate to first evaluate two strong-post W-beam guardrail systems before finalizing the new crash testing procedures and guidelines. For this effort, the modified G4(1S) W-beam guardrail system and the Midwest Guardrail System (MGS) were selected for evaluation and comparison. Five full-scale vehicle crash tests were performed with the two longitudinal barrier systems, in accordance with the Test Level 3 (TL-3) requirements presented in the NCHRP Report 350 Update. For the modified G4(1S) testing program, two 2,270-kg pickup truck vehicles (2270P vehicles) were used: one 3/4-ton, two-door vehicle and one 1/2-ton, four-door vehicle. For the MGS testing program, two 2,270-kg pickup truck vehicles (2270P vehicles) and one 1,100-kg small-car vehicle (an 1100C vehicle) were used, with both pickup truck configurations being evaluated. On the basis of several findings, the NCHRP Project 22-14(2) researchers determined that the 1/2-ton, four-door pickup truck was better suited for use as a surrogate light truck test vehicle than the 3/4-ton, two-door pickup truck. The modified G4(1S) W-beam guardrail system, mounted at the top rail height of 706 mm, provided acceptable safety performance when it was crashed into by the 1/2-ton, four-door pickup truck vehicle, thus meeting the proposed TL-3 requirements presented in the NCHRP Report 350 Update. Testing of the modified G4(1S) W-beam guardrail system was not successful with a 3/4-ton, two-door pickup truck under the TL-3 impact conditions. The MGS was found to meet the TL-3 criteria presented in the NCHRP Report 350 Update for Test Designations 3-10 and 3-11. Satisfactory safety performance was observed with the MGS with both the 1/2-ton, four-door and 3/4-ton, two-door pickup truck vehicles.

Midwest Guardrail System W-Beam-to-Thrie-Beam Transition

For longitudinal barriers, it is common practice to use a standard W-beam guardrail along the required highway segments and to use a stiffened thrie-beam guardrail in a transition region near the end of a bridge. As a result of the differences in rail geometries, a W-beam-to-thrie-beam transition element is typically used to connect and provide continuity between the two rail sections. However, the W-beam-to-thrie-beam transition element has not been evaluated according to current impact safety standards. Therefore, an approach guardrail transition system, including a W-beam-to-thrie-beam transition element, was constructed and crash tested. The transition system was attached to Missouris thrie-beam and channel bridge railing system.

Indenting, buckling and piercing of aluminum beverage cans

Analysis of indenting, buckling and piercing of aluminum beverage cans using both physical testing and computer simulation was performed in order to develop a better understanding of the sidewall structural strength of the cans. This understanding can be used to help design better cans and/or improve manufacturing processes.Simulation of the sidewall indentation was done with an impacting sphere. Parameters investigated included the sphere size and velocity, and the impact height along the sidewall. Buckling simulation of the dented can was then performed. Results from the deformed can buckling model compared well with physical testing based on buckled geometry, buckling load, and external work to buckle. Severe damage to a can that might occur during the manufacturing process was investigated by studying piercing of the can sidewall. Impacts of 5 and 10 m/s were performed with both blunt (flat) and sharp (45° tip) steel rods. It was found that separated elements with tied nodal constraints more accurately represent the failure behavior of the can subjected to a piercing load than merged element nodes. It was also found that the more crushing a can undergoes before piercing occurs, the more energy the can material absorbs. However, there is an upper limit to the crushing based on the speed and shape of the impactor.

Midwest Guardrail System for Long-Span Culvert Applications

Long-span guardrail systems have been recognized as an effective means of shielding low-fill culverts. These designs are popular because, in comparison with other systems that attach posts to the top of the culvert, they are able to shield the culvert safely while creating little additional construction effort and limiting the damage to the culvert and the need for repair. However, previous long-span designs were limited by the need to use long sections of nested guardrail to prevent rail rupture and by the need for large lateral offsets between the barrier and the culvert. The Midwest Guardrail System (MGS) long-span design eliminates those two shortcomings by applying the benefits of the MGS to a long-span design. The MGS long-span design increased vehicle capture and stability because of the increased rail height, limited the potential for pocketing and wheel snag through the use of controlled-release terminal posts adjacent to the unsupported span, and greatly increased the tensile capacity of the rail through the movement of splices away from the posts and the use of shallower post embedment. These features allowed the system to be developed without the use of a nested guardrail and with a minimal barrier offset that placed the back of the guardrail posts even with the front face of the culvert. Two full-scale crash tests were conducted with the MGS long-span design according to the requirements in NCHRP Report 350 for Test Level 3 Test Designation 3-11. Both tests were conducted with the heavier 2,270-kg pickup truck to generate higher rail loads and dynamic deflections. The MGS long-span design met all safety requirements of NCHRP Report 350. The ability of the guardrail with the MGS long-span design to perform safely without a nested rail and a minimal barrier offset makes this new barrier a functional and safe option for the protection of low-fill culverts.

Midwest Guardrail System Adjacent to a 2:1 Slope

A W-beam guardrail is often used to protect motorists from steep roadside slopes adjacent to high-speed roadways. Although previously designed systems have demonstrated acceptable safety performance, the long posts and half-post spacing have proven to be costly and introduce maintenance challenges. Using longer posts is more economical to users than having a system with posts installed at half-post spacing. Furthermore, the improved redirective capacity of the Midwest Guardrail System (MGS) provides the opportunity to eliminate the need for half-post spacing and thereby greatly reduces the cost of placing a barrier at the slope break point. A stiffened version of the MGS was developed for use adjacent to steep roadside slopes. The new design incorporates 2,743-mm (9-ft) long posts with 1,905-mm (75-in.) spacing. With the top of the W-beam mounted at a height of 787 mm (31 in.), this guardrail was successfully crash tested according to the currently proposed NCHRP Report 350 Update safety performance evaluation criteria. Hence, the stiffened MGS guardrail design with full post spacing is acceptable for use on the National Highway System. This new guardrail design will provide a safe and economical alternative for use along highways with steep slopes very close to the travelway.

High-Performance Aesthetic Bridge Rail and Median Barrier

Design of high-performance concrete barriers for heavy vehicles has advanced little in recent years. Barrier improvements were needed in terms of design aesthetics, safety performance, and economy. Advancement was deemed necessary for improved barrier geometry design to reduce vehicle instability and the potential for occupant head slap on the barrier, improved understanding of impact loads for heavy vehicles and use of these loads to optimize barriers, and improved barrier aesthetics. This paper describes the development of two NCHRP Report 350 Test Level 5 (TL-5) barriers that address these needed advancements. First, a TL-5 open concrete bridge rail was designed with a focus on determining accurate impact loads and providing a barrier geometry with improved safety and aesthetics. Next, a TL-5 concrete median barrier was developed through rigorous analysis of barrier shape options to determine the safest and most economic shape. Structural design of the barrier was also optimized to minimize cost while meeting the design loads for heavy vehicles. The open concrete bridge rail and the concrete median barrier were successfully full-scale crash-tested according to the TL-5 safety requirements set forth in NCHRP Report 350. These designs represent a major advancement in the safety and economy of high-performance concrete barriers.

Development and Implementation of the Simplified Midwest Guardrail System Stiffness Transition

The varied lateral stiffness between bridge rails and approach guardrail systems may cause vehicle pocketing or wheel snagging to occur near rigid bridge rail ends. To mitigate this potential hazard, an approach guardrail transition (AGT) is used to provide a gradual increase in the lateral stiffness of the barrier between the W-beam guardrail system and the bridge railing. However, these transitions can also cause a propensity for vehicle pocketing or wheel snagging if the change in lateral stiffness occurs too rapidly. Recently, a stiffness transition based on NCHRP Report 350 was developed for use with the Midwest Guardrail System (MGS) and a stiff Thrie beam AGT, and successful testing was performed close to the upstream end of the AGT. The transition was designed with three sizes of steel posts, one of which was nonstandard for state departments of transportation. Thus, a simplified version of the original MGS stiffness transition that used two common sizes of steel posts was developed and was subjected to full-scale crash testing according to Test Level 3 as set forth in the Manual for Assessing Safety Hardware. Subsequently, dynamic post properties obtained from bogie testing and numerical simulations were used to develop an equivalent wood post version of the simplified MGS stiffness transition. Recommendations are made regarding the attachment of the stiffness transitions to FHWA-accepted Thrie beam bridge rail AGTs.

Tie-Downs and Transitions for Temporary Concrete Barriers

Temporary concrete barriers are one of the most common types of roadside hardware found on the nations highways. However, unresolved issues exist for some installations. These issues include the need for a tie-down system for barrier installations placed on asphalt roadway surfaces and an approach transition between temporary concrete barriers and rigid barriers. The objective of this research was to design a tie-down temporary barrier for use on asphalt road surfaces and then apply that tie-down system to the design of an approach transition from freestanding to rigid barriers. The tie-down and transition systems were to be evaluated according to Test Level 3 safety performance criteria set forth in NCHRP Report No. 350. For the asphalt tie-down system, three steel pins were installed in holes on the front face of the barrier. The new tie-down design was crash tested according to NCHRP Report No. 350 Test Designation 3-11. The test was judged acceptable, barrier deflections were reduced, and all barrier...