Seismic　fragility　analysis　methods　commonly　used　for　assessing　structural　components　and　systems　have　certain　limitations.　This　paper　introduces　a　new　semi-parametric　approach　for　structural　component　fragility　analysis,　the　TKC　method.　This　method　is　based　on　log-transformed　kernel　density　estimation　(log-TKDE)　and　copula　functions,　which　establish　the　joint　probability　distribution　(JPD)　of　a　structural　response　value　(d)　and　a　disaster-inducing　factor　strength　parameter　(alpha)　using　log-TKDE　and　match　the　marginal　cumulative　distributions　(MCDs)　of　d　and　a　via　bivariate　copula　functions.　A　novel　method　for　evaluating　structural　system　fragility　is　also　proposed　based　on　the　R-vine　copula　function.　This　approach　accounts　for　the　intricate　correlations　among　different　components,　providing　a　precise　estimation　of　the　multidimensional　JPD.　The　reliability　and　accuracy　of　the　proposed　methods　are　demonstrated　through　a　seismic　fragility　analysis　of　a　sea-crossing　cable-stayed　bridge　under　earthquake　load.　Furthermore,　a　multi-hazard　fragility　analysis　of　bridge　components　and　systems　is　conducted　considering　hazards　such　as　earthquake,　wind,　and　wave　loads.　A　comparison　is　made　with　the　seismic　fragility　of　bridges　subjected　to　earthquake　loads　alone.　The　results　show　that　the　median　and　95%　confidence　of　the　damage　probability　of　structural　components　calculated　by　the　TKC　method　and　Monte　Carlo　simulation　(MCS)　closely　match,　which　validates　the　proposed　method.　The　TKC　method　is　also　more　accurate　and　computationally　efficient　than　the　MCS　method　with　the　same　Bootstrap　sample　size　and　confidence　level　(95%).　The　proposed　structural　system　fragility　assessment　method　based　on　the　R-vine　copula　accounts　for　complex　correlations　between　components　and　yields　more　accurate　results　than　the　first-order　boundary　method.　Load　spectrum　characteristics,　structural　component　characteristics,　and　other　factors　cause　the　multihazard　fragility　of　bridge　components　and　systems　to　differ　substantially　from　their　seismic　fragility.　The　difference　rate　of　system　damage　probability　can　reach　28.82%.　In　evaluating　the　anti-disaster　performance　of　seacrossing　bridges,　it　is　necessary　to　incorporate　the　marine　environmental　load　and　consider　the　dynamic　response　coupling　effect　of　the　bridge　excited　by　seafloor　ground　motions　with　extreme　wind　and　wave　loads.　This　approach　can　guide　the　optimization　of　bridge　designs　and　facilitate　multi-hazard　fragility　analysis　in　accordance　with　real　damage　probabilities.