# Load Models Representative of Brazilian Actual Traffic in Girder-Type Short-Span Highway Bridges
## 10 Conclusions  
This paper presents and describes some of the steps performed to evaluate the current live load model of the Brazilian highway bridges design code and to develop new ones to adequately represent the extreme effects imposed by actual traffic. From the collection and acquisition of traffic data, the assembly of a database, and consideration of structural models in adjusted grids representing typical girder-type short span highway bridges, simulations of free-flow traffic were carried out to obtain static responses at critical cross-sections. Then, dynamic analyses were performed, considering the interaction between vehicles, bridges' structure, and pavement, aiming to obtain dynamic amplification factors representative of heavy traffic, which multiply the static characteristic values (determined by the extrapolation of the effects' PDF).  
The main contributions and conclusions can be summarized as follows:  
1. Two load models were proposed to represent the Brazilian commercial traffic. One of them considers a single design lane and the design vehicle located in the worst transverse position (as in NBR 7188 current model). The other one divides the effective deck width into three traffic lanes, which is the same configuration as the Eurocode 1 model LM1.
2. Neither the current NBR 7188 code load model (TB-450) nor the two proposed ones were able to fit traffic effects in all possible situations. Discrepancies between the target values and the effects caused by the proposed load models illustrate the difficulty in simultaneously fulfilling several requirements, a remarkable feature of multi-objective optimization problems.
3. However, the representativeness of the new proposed load models is considerably greater than the one from current NBR 7188 load model.
4. Results reiterate that TB-450 may not adequately represent the effects of the actual commercial traffic vehicles on the most representative bridges from the national highways network.  
Next work steps compass:  
1. Inclusion of longer spans (in mixed flow and jams).
2. Acquisition of more recent WIM traffic data.
3. Recalibration of the load models.
4. Calibration of load and resistance factors via structural reliability analyses.  
Conceptualization, C.E.R. and M.S.P.; methodology, C.E.R., M.S.P. and L.V.S.S.; software, C.E.R. and H.M.d.O.; formal analysis, C.E.R. and H.M.d.O.; investigation, C.E.R. and H.M.d.O.; writing--original draft preparation, C.E.R.; writing--review and editing, M.S.P.; supervision, M.S.P. and L.V.S.S.; funding acquisition, M.S.P. and L.V.S.S. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior--Brasil (CAPES)--Finance Code 001. This research has also received funding from CNPq-Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Brazil.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Conflicts of Interest:** The authors declare no conflict of interest.