Tsunamis　pose　a　significant　threat　to　coastal　engineering.　A　comprehensive　physical　experiment　was　conducted　to　examine　the　effect　of　air　chambers　on　vertical　structures　with　overhanging　horizontal　slabs　under　tsunami　bores.　This　paper,　serving　as　the　second　part　of　the　series,　contrasts　with　conditions　without　air　chambers　(flat　slab　as　Part　I)　to　underscore　the　chamber＇s　effects.　The　experiment　employed　dam-break　waves　to　simulate　tsunamis,　and　the　collected　pressure　data　and　experimental　images　were　analyzed.　Results　show　that　the　chambers　restrict　water　flow,　thereby　enhancing　the　impact　on　the　slab.　This　focusing　effect　greatly　increases　both　maximum　uplift　and　horizontal　pressure　(by　almost　1.3　times).　The　uplift　pressure　rises　with　increasing　chamber　volume,　while　horizontal　pressure　escalates　with　greater　beam　volume.　However,　both　pressures　diminish　as　slab　height　increases.　Water　flowing　into　the　chambers　disperses　air,　generating　numerous　bubbles　that　accumulate　above,　forming　an　air　layer　that　reduces　pressure　signal　fluctuations.　This　phenomenon　of　entrained　and　trapped　air　is　compared　and　analyzed　with　existing　literature.　The　maximum　pressure　of　the　nearshore　air　chamber　is　greater　than　that　of　the　offshore　air　chamber　by　13%　(3.68　kPa　vs.　3.27　kPa),　while　the　quasi-steady　pressures　of　the　two　are　almost　equal.　Differences　in　pressure　between　chambers　result　from　the　sequence　of　water　flow　impacts　and　reflections.　New　design　envelope　equations　and　conversion　coefficients　are　proposed　based　on　experimental　data.　The　focusing　coefficient,　considering　bore　height,　slab　height,　and　chamber　parameters,　is　summarized.　Novel　equations　for　estimating　pressure　on　a　flat　slab　with　specific　chambers　are　proposed,　with　validation　results　indicating　high　accuracy.　©　2024　Elsevier　Ltd