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      <div class="title_refTopic" id="xps10_pagetitle">PLOAD </div>
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      <h4 class="refClassification">Static Pressure Load </h4>
      <p class="para_refTopic">Defines a uniform static pressure load on a triangular or quadrilateral surface comprised of surface elements and/or the faces of solid elements. </p>
      <div class="title_refCategory">Format: </div>
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                     <p class="para_td">PLOAD </p>
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                     <p class="para_td">SID </p>
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                     <p class="para_td">P </p>
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                     <p class="para_td">G1 </p>
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                     <p class="para_td">G2 </p>
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                     <p class="para_td">G3 </p>
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                     <p class="para_td">G4 </p>
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                     <p class="para_td">&nbsp; </p>
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                     <p class="para_td">&nbsp; </p>
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                     <p class="para_td">&nbsp; </p>
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      <div class="title_refCategory">Example: </div>
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                     <p class="para_td">PLOAD </p>
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                     <p class="para_td">1 </p>
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                     <p class="para_td">-4.0 </p>
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                     <p class="para_td">&nbsp; </p>
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                     <p class="para_td">&nbsp; </p>
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      <div class="title_refCategory">Fields:</div>
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                     <p class="para_th"><b class="uiTerm">Field </b></p>
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                     <p class="para_th"><b class="uiTerm">Contents </b></p>
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                     <p class="para_td">SID </p>
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                     <p class="para_td">Load set identification number.  (Integer &gt; 0) </p>
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                     <p class="para_td">P </p>
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                     <p class="para_td">Pressure.  (Real) </p>
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                     <p class="para_td">Grid point identification numbers.  (Integer &gt; 0; G4 may be zero or blank.) </p>
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      <div class="title_refCategory">Remarks: </div>
      <div class="refCategoryContent">
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            <li>
               <p class="para_item">In the static solution sequences, the load set ID (SID) is selected by the Case Control command LOAD.  In the dynamic solution sequences, SID must be referenced in the LID field of an LSEQ entry, which in turn must be selected by the Case Control command LOADSET. </p>
            </li>
            <li><a name="ref64637"></a><p class="para_item">The grid points define either a triangular or a quadrilateral surface to which a pressure is applied.  If G4 is zero or blank, the surface is triangular. </p>
            </li>
            <li>
               <p class="para_item">In the case of a triangular surface, the assumed direction of the pressure is computed according to the right-hand rule using the sequence of grid points G1, G2, G3 illustrated in <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/18topic_40.html#ref66994');return(false);">Figure 17-</a>. 
               </p><a name="ref66994"></a><div class="figure">
                  <p align="center"><img align="bottom" src="graphics/bulkp-fig15.gif"></p>
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               <div class="title_figure">Figure. Pressure Convention for Triangular Surface of Surface Elements and/or the Faces of Solid Elements </div>
               <p class="para_item">The total load on the surface (see <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/18topic_40.html#ref31607');return(false);">Figure 17-</a>), AP, is divided into three equal parts and applied to the grid points as concentrated loads.  A minus sign in field 3 reverses the direction of the load. 
               </p>
            </li>
            <li>
               <p class="para_item">In the case of a quadrilateral surface, the grid points G1, G2, G3, and G4 should form a consecutive sequence around the perimeter.  The right-hand rule is applied to find the assumed direction of the pressure.  Four concentrated loads are applied to the grid points in approximately the same manner as for a triangular surface.  The following specific procedures are adopted to accommodate irregular and/or warped surfaces: </p>
               <ul>
                  <li>
                     <p class="para_item">The surface is divided into two sets of overlapping triangular surfaces.  Each triangular surface is bounded by two of the sides and one of the diagonals of the quadrilateral. </p>
                  </li>
                  <li>
                     <p class="para_item">One-half of the pressure is applied to each triangle, which is then treated in the manner described in Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/18topic_40.html#ref64637');return(false);">63-2. </a></p><a name="ref31607"></a><div class="figure">
                        <p align="center"><img align="bottom" src="graphics/bulkp-fig16.gif"></p>
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                     <div class="title_figure">Figure. Pressure Convention for Quadrilateral Surface of Surface Elements and/or the Faces of Solid Elements </div>
                  </li>
               </ul>
            </li>
            <li>
               <p class="para_item">The follower force effects due to loads from this entry are included in the stiffness in all linear solution sequences that calculate a differential stiffness. The solution sequences are SOLs 103, 105, 107 to 112, 115 and 116 (see also the parameter <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/08ref24356_2.html#ref32029');return(false);">&ldquo;FOLLOWK&rdquo; </a>). In addition, follower force effects are included in the force balance in the nonlinear static and nonlinear transient dynamic solution sequences, SOLs 106, 129, 153, and 159, if geometric nonlinear effects are turned on with PARAM,LGDISP,1. The follower force stiffness is included in the nonlinear static solution sequences (SOLs 106 and 153) but not in the nonlinear transient dynamic solution sequences (SOLs 129 and 159). 
               </p>
            </li>
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      <div class="title_refCategory">Remarks related to SOLs 601 and 701: </div>
      <div class="refCategoryContent">
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            <li>
               <p class="para_item">To apply a pressure load with constant magnitude, SID is selected by Case Control command LOAD = SID for both static and transient analyses. </p>
            </li>
            <li>
               <p class="para_item">To apply a time-dependent pressure load, SID is referenced by the field EXCITEID = SID in the TLOAD1 entry. Time-dependent loads are selected by Case Control command DLOAD. </p>
            </li>
            <li>
               <p class="para_item">In large deformation analysis, the direction of pressure loads follows the deformation of the element by default. The use of LOADOPT = 0 in NXSTRAT entry causes pressure loads to be independent of deformation, i.e., the direction of pressure loads maintains its original direction. </p>
            </li>
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