The invention relates to a fixed and/or stabilized fiber structure from a fibrous material as well as from an agent for its fixing and stabilizing. The agent for fixing and stabilizing is a statistical copolyester which is formed from the diacid components terepththalic acid and, optionally, isophthalic acid as well as the diol components butanediol, diethylene glycol and triethylene glycol. A method of manufacturing this fiber structure is also provided. The fiber structure is used as a reinforcement material for polymer matrices, in particular epoxy resins. A fiber composite material containing at least one thermosetting resin as well as the fiber structure in accordance with the invention is furthermore provided.