We get the results of the load assessment design in the form of tables, as shown below: As we went through the article, we understood the importance of load capacity, the philosophy behind it, and the process to do the same. MIDAS Civil provides the platform for planning an engineer`s load capacity. Therefore, it helps the engineer accurately simulate the model with the construction phases, then perform the analysis and design of it, and then facilitate load capacity planning for the same bridge. midas civil offers the AASHTO code LRFR 19 for calculating the nominal load. The functionality is defined in such a way that user input can be provided in the simplest way. The SHV load models apply to the permissible voltage weighting, load factor weighting and load and resistance factor weighting in accordance with clauses 6A and 6B of the MBE. The choice of load-bearing method should be consistent with the FHWA policy note on bridge load ratings for the National Bridge Inventory dated October 30, 2006. Figure 8: Midas Civil Load Capacity Report This helps us to know the bridge`s ability to carry the payload for the design and legal vehicles allowed, overloads and determine weight reservations. Therefore, bridge assessment factors can be used to make decisions on the need for: Purpose: Bridges that do not have sufficient capacity in the rated load must be designed for legal loads to determine the need for a load position or reinforcement. The schedule described above will be included in the review of Metric 13 under the National Bridge Inspection Program (NBINP); In particular, all bridges that meet Group 1 criteria are expected to be loaded for VHS by the end of 2017. Please work with your state to help them develop appropriate measures to meet these deadlines. If your state is developing or implementing a corrective action plan (PCA) for structural bridges, the BCP should be reviewed and, if necessary, amended to reflect the VHS classification for these bridges and timelines.

The nominal load process can be understood from the diagram flow below: The nominal load based on the nominal level of operation usually describes the maximum permissible payload to which the structure can be exposed. In general, classification at the operational level can shorten the life of the bridge Condition B: The Crown has its own vehicle models for legal loads and verifies that the State`s regulatory load models include the applicable AASHTO SHV load models specified in Annex D6A and Figure 6B.9.2-2 of the 1st edition of the MBE (Figure 6B.7.2-2 of the 2nd edition of the MBE). and state regulatory load models were included in the assessment and display analyses of all bridges. Types of VHS, such as six- or seven-axis VHS, which are excluded by state laws, do not need to be considered. This second step provides a unique safe loading capacity (for a specific truck configuration) that applies to AASHTO and state legal charges. Purpose: The carrying capacity covered by the licence assesses the safety and operational condition of bridges when reviewing applications for permits to pass vehicles beyond the weight restrictions established by law. A State may use an approach other than the one described above to regulate the carrying capacity of VHS for bridges in its inventory; However, the approach needs to be reviewed and formally accepted by the FHWA. Figure 7: Load-bearing capacity results for bending in tabular form The FHWA acknowledges that there are bridges in the fleet that have not been assessed for HSV and that it is not possible to include VH in the assessments for the entire stock at the same time. The FHWA establishes the following timelines for the evaluation of bridges for VHS when neither condition A nor condition B are met: The load-bearing capacity function is facilitated for both composite steel and PSC bridges. Figure 2: Application examples after assessing the load-bearing capacity of a bridge If, for both groups, a reassessment is warranted due to changes in structural condition, loads or configuration, or other requirements, the reassessment should include HSV. How does the supporting philosophy differ from the philosophy of bridge building? Bridge load bearing capacity is a method for assessing the suitability of various structural components to accommodate specific payloads.

Simply put, this is the determination of the load-bearing capacity of the bridge. Load ratings are expressed as nominal factor (RF) or tonnage (for legal and registered vehicles) for a given vehicle. NCHRP Project 12-63 (Report 575, 2007) examined changes in truck configuration and government legal loads and found that AASHTO Type 3, 3-S2 and 3-3 vehicles are not representative of all legal loads, particularly VHS. As a result, legal burden models for VHS were developed and adopted by AASHTO in 2005, recognizing the urgent need to include VHS in a state`s sustainability process when VHS operates in a state. The MBE`s SHV load models include SU4, SU5, SU6, and SU7, which represent four- to seven-axis SHVs, as well as a notional rated load (NRL) model, which wraps the four single-load models and serves as a screen load. If the load factor of the NRL model is equal to or greater than 1.0, it is not necessary to evaluate SU4, SU5, SU6 and SU7 for single loads. However, if the load factor of the NRL is less than 1.0, the individual loads SU4, SU5, SU6 and SU7 must be taken into account in the nominal load and the reservation. This third level of classification should only be applied to bridges that have sufficient capacity to support legal loads.

In other words, the carrying capacity of the permit should only be used if the bridge has a nominal factor greater than 1.0 when evaluating regulatory AASHTO loads. VHS are individual vehicles with multiple axles close together that have been introduced by the trucking industry over the past decade. Examples include dump trucks, construction vehicles, garbage trucks, and other dump trucks. PHEVs generally conform to the Bridge B formula and are therefore considered legal in all states, unless the laws of one state specifically exclude the use of such vehicles. VHS generate higher force effects and therefore result in lower load ratings for some bridges, especially those with shorter span or load length, such as cross floor girders, compared to AASHTO Type 3, 3-S2 and 3-3 legal loads and HS20 design load. Therefore, VHS, i.e. SU4, SU5, SU6 and SU7 or NRL, shall be included in rating and accounting analyses in accordance with Articles 6A.2.3 and 6B.9.2 of the 1st edition of the EMB (Article 6B.7.2 of the 2nd edition of the MBE), unless one of the following conditions is met: The purpose of this memorandum is to clarify the FHWA`s position on the analysis of Special Transport Vehicles (VHS) as defined in AASHTO. Bridge Evaluation Manual (EMB) during the bearing capacity and positioning of bridges to meet the requirements of the National Bridge Inspection Standards (NBAS). The purpose of the NBPS Load Capacity and Positioning Regulations is to ensure that all bridges are properly assessed for safe viability, taking into account all unrestricted legal burdens, including current government permits, and that bridges are properly marked when required in accordance with the ROM.

The LRFR methodology includes three different levels of assessment: Condition A: The state verifies whether state laws prohibit the use of HSV; or We ask that you share this memorandum with your state or federal agency partner. Any issues that cannot be resolved at the department office level should be directed to Lubin Gao at lubin.gao@dot.gov or 202-366-4604. Group 1: Bridges with a shortest span not exceeding 200 feet should be inspected after their next NPS inspection, but no later than 31 feet. December 2017, which were last evaluated by: In addition to the tabular results, an Excel report with the results is also created in order to facilitate the designer`s work in the best possible way: The RF value shall be used in accordance with the LRFR standard as follows: Calculation of the scoring factor (RF) according to AASHTO LRFR 2019: The outcome of each evaluation serves a specific purpose and also informs about the need for additional evaluations. This is an assessment of the first level of bridges. The performance of existing bridges is measured in accordance with current FSRA bridge design standards. Figure 1: Steel composite girder I bridge assessed for load capacity group 2: assess bridges that are not part of group 1 by 31 December 2022.