To　investigate　the　effects　of　cylinders　placed　parallel　to　the　venting　direction　on　the　structural　response　of　the　vessel　walls　to　an　explosion,　25　batches　of　vented　explosion　tests　were　conducted　in　a　1　m3　rectangular　vessel.　Two　types　of　structural　response　with　different　amplitudes　and　frequency　distributions　were　observed　and　evaluated　by　comparing　the　vibration　data　with　both　the　pressure　data　and　high-speed　videos.　A　low-amplitude　structural　response　of　approximately　150–250　m/s2,　which　increased　slightly　as　VBR　increased,　was　triggered　by　a　combination　of　the　initial　flame　propagation,　external　explosion,　Helmholtz　oscillations,　and　the　Taylor　instability.　A　high-amplitude　structural　response　of　approximately　9500　m/s2　was　also　observed,　which　decreased　sharply　as　VBR　increased.　Additionally,　the　high　amplitude　response　was　never　observed　when　more　than　two　cylinders　were　present　in　the　vessel.　The　high　amplitude　response　was　triggered　due　to　the　coupling　between　the　acoustic　wave,　the　flame,　and　the　resonance　of　the　vessel.　The　presence　of　obstacles　did　not　increase　the　severity　of　the　structural　responses　under　the　current　experimental　conditions.　To　the　contrary,　the　presence　of　obstacles　in　the　container　attenuated　or　even　inhibited　the　high-amplitude　vibration　of　the　container　caused　by　the　explosion.　©　2020　Elsevier　Ltd