Significantly progress has been made in the preceding two decades in the area of seismic engineering. Design codes are very quickly migrating from prescriptive procedures intended to preserve life safety to reliability-based design with less prescription intended to quantify risk associated with designs. Probabilistic performance-based design is in between traditional prescriptive design and full reliability-based methodologies. This investigation is performed to evaluate confidence levels in concentrically braced steel frames. Two types of connections included rigid and simple beam to column connections are selected for inverted V braced frames and they are used for evaluation of the effect of such connections on the seismic behavior of chevron braced frames. Therefore, 6 frames with 3, 6 and 9 storey in height and with rigid and simple beam to column connections are selected. These frames are designed according to Iranian Code of Practice for Seismic Resistant Design of Buildings. More than 5000 time history analysis are performed in this investigation and 20 ground motion records with 2% probability of exceedance in 50 years are used. For evaluating confidence levels and estimating capacity of these braced frames, the Incremental Dynamic Analysis (IDA) is used and all are scaled to different levels of hazard. Assuming log-normal distribution of demand and capacity, uncertain and random components are computed using the logarithmic standard deviation of these parameters. By using the total probability theorem and simplified equations developed in FEMA-351, the uncertainties, randomness and finally confidence levels in each frame has been calculated. Results show that the confidence level decreses as the height of the frame increases. The level of confidence for meeting a specific performance level (CP) in braced frames with rigid beam to column connections is more than this level in such frames with simple connections. It’s perhaps because of more calculated uncertainties and randomness in such frames.