Transverse Lane/Vehicle Placement:
Upon receiving roadway dimensions from the user, OpenBrIM seamlessly manages lane placement in the transverse direction for influence surface-based live load analysis. In a 50-foot roadway, for instance, it can accommodate 4, 3, 2, or 1 lane(s), with multiple presence factors of 1.2, 1, 0.85, and 0.65. OpenBrIM rapidly explores these alternatives, shifting lanes by one foot in the transverse direction and assessing billions of potential configurations within seconds, thanks to its efficient, multi-threaded GPU-based architecture.
Properties
Lane Width: The combined width of the vehicle (usually 6 ft) and its margin (1 or 2 feet) should not exceed the Lane Width, which is typically 12 ft. Margin btw. Vehicle & Lane Edge : This is referring to the lateral distance from both sides of the lane where vehicles cannot be placed. The wheel load of any vehicle cannot be positioned in this specific location. .png?version=2&modificationDate=1678263580934&cacheVersion=1&api=v2) Image Modified
VehiclesIt is utilized to define a vehicle, vehicle's impact factor and direction within a single Design Lane in the longitudinal direction. Typically, AASHTO recommends placing one or two vehicles in the longitudinal direction within a single lane. Using the vehicle 1, vehicle 2, vehicle 3, and vehicle 4 parameters, OpenBrIM allows users to position up to four vehicles in the Design Lane's longitudinal direction. It should be noted that this does not apply to the placement of the Design Lane in the transverse direction, which is determined by the roadway width and design lane width. Vehicle 1: The vehicles defined in the "Vehicles" section are assigned to the parameter that specifies the vehicle to be positioned within the Design Lane. This represents the first vehicle defined in the longitudinal direction. Vehicle 1 Impact Factor: According to AASHTO Table 3.6.2.1.1, the dynamic allowance factor is indicated as 75% for Deck Joints - All Limit States, 15% for All Other Components, Fatigue and Fracture Limit State, and 33% for other limit states. In OpenBrIM, this information is used to specify the impact factor as 1.75, 1.15, and 1.33, respectively. This parameter increases the vehicle's wheel loads using the specified factors. Vehicle 1 Left Wheel Factor: The left wheel impact factor is detailed in AREMA for rails; however, live loads can also include left wheel factor definitions tailored for specific needs. Since moving vehicles may experience various changes in load distribution due to movement, the loads applied by the wheels can vary in magnitude. For instance, in the case of a sharp turn, the left wheels may experience a 50% reduction in vertical loads. Such scenarios occur in real life, and these parameters can also be defined in OpenBrIM.  Image AddedSection 1.3.5.d: Impact Load Due to Rocking Effect (RE) The rocking effect is created by the transfer of load from the wheels on one side of a car or locomotive to the other side due to periodic lateral rocking of the equipment. The RE shall be calculated from loads applied as a vertical force couple, with each force being 20 percent of the wheel load (excluding impact). These forces act downward on one rail and upward on the opposite rail. This force couple shall be applied to each track in the direction that generates the greatest force in the member under consideration. Vehicle 1 Direction[Both/Backward/Forward]: In the context of a vehicle, x=0 is considered to be the location of the front of the vehicle in vehicle definition. Moving in the forward direction means increasing alignment station values, while moving in the opposite direction is considered backward. If "both" is chosen, placement is carried out in both forward and backward directions, but only the critical placement is reported. According to AASHTO guidelines, using both directions is generally recommended, but for permit trucks with unique circumstances, it may be acceptable to use only one direction. Vehicle 2: Vehicle 2 Impact Factor: Vehicle 2 Left Wheel Factor: Vehicle 2 Direction:  Image ModifiedVehicle 3: Vehicle 3 Impact Factor: Vehicle 3 Left Wheel Factor: Vehicle 3 Direction: Vehicle 4: Vehicle 4 Impact Factor: Vehicle 4 Left Wheel Factor: Vehicle 4 Direction: Lane LoadLane Load Magnitude: The design lane load, as defined in AASHTO LRFD, is typically 0.64 klf and expressed as force per unit length. It is used in conjunction with the design truck or tandem. OpenBrIM applies the lane load in both transverse and longitudinal directions on a design lane only if it increases the critical force effect. As indicated in the screenshot below, the red and yellow regions show the areas that can be loaded with the lane load for negative force effects, whereas the green and blue regions show the areas that can be loaded with the lane load for positive force effects. Lane Load Width: According to AASHTO standards, the typical width for a lane load is 10 ft. Entered value is utilized convert lane load to the pressure per square foot. For instance, if the entered value for lane load magnitude is 0.64 klf and the lane load width is 10 feet, the pressure per square foot can be computed as follows: 0.64 klf ÷ 10 feet = 0.064 kips/ft Thus, the pressure per square foot would be 0.064 kips/ft². Afterwards, this value is multiplied by the areas (i.e., red and yellow regions, as shown in the screenshot below) that contribute to maximizing the lane load force for negative force effect.  Image ModifiedVehicle Placement SettingsMin. Vehicle Spacing | 
