<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"
	xmlns:content="http://purl.org/rss/1.0/modules/content/"
	xmlns:wfw="http://wellformedweb.org/CommentAPI/"
	xmlns:dc="http://purl.org/dc/elements/1.1/"
	xmlns:atom="http://www.w3.org/2005/Atom"
	xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
	xmlns:slash="http://purl.org/rss/1.0/modules/slash/"
	>

<channel>
	<title>kruipcoëfficiënt &#8211; BuildSoft Support</title>
	<atom:link href="https://support.buildsoft.eu/fr/article-tags/kruipcoefficient/feed/" rel="self" type="application/rss+xml" />
	<link>https://support.buildsoft.eu/fr/</link>
	<description>BuildSoft Support</description>
	<lastBuildDate>Mon, 15 Jun 2026 10:36:04 +0000</lastBuildDate>
	<language>fr-FR</language>
	<sy:updatePeriod>
	hourly	</sy:updatePeriod>
	<sy:updateFrequency>
	1	</sy:updateFrequency>
	<generator>https://wordpress.org/?v=6.2.14</generator>
	<item>
		<title>Online creep coefficient calculator</title>
		<link>https://support.buildsoft.eu/fr/knowledge-base/online-creep-coefficient-calculator/</link>
		
		<dc:creator><![CDATA[Dorien Elleboog]]></dc:creator>
		<pubDate>Mon, 15 Jun 2026 10:35:37 +0000</pubDate>
				<guid isPermaLink="false">https://support.buildsoft.eu/?post_type=ht_kb&#038;p=29833</guid>

					<description><![CDATA[Creep Coefficient &#966;(t, t&#8320;) Eurocode EN 1992-1-1:2004 &#8212; Annex B, Equations B.1 &#8211; B.9 t&#8320; &#8212; Age at loading [days] t &#8212; Age considered [days] fck &#8212; Char. strength [N/mm&#178;] RH &#8212; Relative humidity [%] u &#8212; Exposed perimeter [mm] Ac &#8212; Cross-section area [mm&#178;] Cement class S &#8212; slow...]]></description>
										<content:encoded><![CDATA[
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script> 
 <style>
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

    body {
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      font-size: 15px;
      background: #f4f4f2;
      color: #1a1a1a;
      padding: 2rem 1rem;
      line-height: 1.6;
    }

    .container {
      max-width: 820px;
      margin: 0 auto;
      background: #fff;
      border-radius: 12px;
      border: 1px solid #e0dfd8;
      padding: 2rem 2.5rem;
    }

    h1 {
      font-size: 20px;
      font-weight: 500;
      margin-bottom: 4px;
      color: #111;
    }

    .subtitle {
      font-size: 13px;
      color: #666;
      margin-bottom: 1.75rem;
    }

    /* ── Form grid ── */
    .form-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
      gap: 14px;
      margin-bottom: 1.5rem;
    }

    .field {
      display: flex;
      flex-direction: column;
      gap: 5px;
    }

    .field label {
      font-size: 13px;
      color: #555;
    }

    .field label em {
      font-style: italic;
      color: #111;
    }

    .field label .unit {
      font-size: 11px;
      color: #888;
    }

    .field input,
    .field select {
      height: 38px;
      padding: 0 10px;
      border: 1px solid #ccc;
      border-radius: 7px;
      font-size: 14px;
      color: #111;
      background: #fff;
      outline: none;
      transition: border-color 0.15s;
      width: 100%;
    }

    .field input:focus,
    .field select:focus {
      border-color: #5046e4;
      box-shadow: 0 0 0 3px rgba(80,70,228,0.12);
    }

    .field input.error {
      border-color: #e24b4a;
    }

    /* ── Divider ── */
    .divider {
      height: 1px;
      background: #eee;
      margin: 1.5rem 0;
    }

    /* ── Result area ── */
    .result-area {
      background: #f7f6f2;
      border-radius: 10px;
      padding: 1.25rem 1.5rem;
      border: 1px solid #e5e4dc;
    }

    .result-main {
      display: flex;
      align-items: baseline;
      gap: 10px;
      margin-bottom: 1rem;
      min-height: 42px;
    }

    .result-label {
      font-size: 15px;
      color: #555;
    }

    .result-value {
      font-size: 36px;
      font-weight: 500;
      color: #111;
      letter-spacing: -0.5px;
    }

    .result-placeholder {
      font-size: 15px;
      color: #999;
      font-style: italic;
    }

    /* ── Intermediate steps grid ── */
    .steps-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
      gap: 8px;
      margin-top: 0.5rem;
    }

    .step-card {
      background: #fff;
      border: 1px solid #e5e4dc;
      border-radius: 8px;
      padding: 10px 12px;
    }

    .step-card .sc-label {
      font-size: 11px;
      color: #888;
      margin-bottom: 2px;
    }

    .step-card .sc-value {
      font-size: 15px;
      font-weight: 500;
      color: #111;
    }

    .step-card .sc-ref {
      font-size: 11px;
      color: #aaa;
      margin-top: 1px;
    }

    /* ── Notices ── */
    .notice {
      font-size: 12px;
      border-radius: 7px;
      padding: 7px 11px;
      margin-top: 10px;
      display: none;
    }

    .notice.warn  { background: #faeeda; color: #7a4b08; border: 1px solid #f5c97a; }
    .notice.error { background: #fcebeb; color: #8b2020; border: 1px solid #f5b3b3; }

    /* ── Footer ── */
    .footer {
      margin-top: 1.5rem;
      font-size: 12px;
      color: #aaa;
      text-align: center;
    }
  </style>
<div class="container">
  <h3>Creep Coefficient &phi;(t, t&#8320;)</h3>
  <p class="subtitle">Eurocode EN 1992-1-1:2004 &mdash; Annex B, Equations B.1 &ndash; B.9</p>

  <div class="form-grid">

    <div class="field">
      <label for="t0"><em>t&#8320;</em> &mdash; Age at loading <span class="unit">[days]</span></label>
      <input type="number" id="t0" value="28" min="1" step="1" placeholder="28" />
    </div>

    <div class="field">
      <label for="t"><em>t</em> &mdash; Age considered <span class="unit">[days]</span></label>
      <input type="number" id="t" value="" min="1" step="1" placeholder="e.g. 18250" />
    </div>

    <div class="field">
      <label for="fck"><em>f<sub>ck</sub></em> &mdash; Char. strength <span class="unit">[N/mm&sup2;]</span></label>
      <input type="number" id="fck" value="" min="12" max="90" step="1" placeholder="e.g. 30" />
    </div>

    <div class="field">
      <label for="rh"><em>RH</em> &mdash; Relative humidity <span class="unit">[%]</span></label>
      <input type="number" id="rh" value="50" min="40" max="100" step="1" placeholder="50" />
    </div>

    <div class="field">
      <label for="u"><em>u</em> &mdash; Exposed perimeter <span class="unit">[mm]</span></label>
      <input type="number" id="u" value="" min="1" step="1" placeholder="e.g. 1200" />
    </div>

    <div class="field">
      <label for="ac"><em>A<sub>c</sub></em> &mdash; Cross-section area <span class="unit">[mm&sup2;]</span></label>
      <input type="number" id="ac" value="" min="1" step="1" placeholder="e.g. 90000" />
    </div>

    <div class="field">
      <label for="cement">Cement class</label>
      <select id="cement">
        <option value="S">S &mdash; slow (&alpha; = &minus;1)</option>
        <option value="N" selected>N &mdash; normal (&alpha; = 0)</option>
        <option value="R">R &mdash; rapid (&alpha; = +1)</option>
      </select>
    </div>

  </div><!-- /.form-grid -->

  <div class="divider"></div>

  <div class="result-area">
    <div class="result-main" id="result-main">
      <span class="result-placeholder">Fill in all fields to see &phi;(t, t&#8320;)</span>
    </div>
    <div class="steps-grid" id="steps-grid" style="display:none;"></div>
    <div class="notice warn"  id="warn-msg"></div>
    <div class="notice error" id="err-msg"></div>
  </div>

  <p class="footer">Reference: EN 1992-1-1:2004 Annex B &mdash; Basic equations for determining the creep coefficient</p>
</div><!-- /.container -->


<script>
/**
 * Eurocode EN 1992-1-1 Annex B
 * Creep Coefficient φ(t, t₀) Calculator
 *
 * Equations implemented:
 *   B.1  φ(t,t₀) = φ₀ · βc(t,t₀)
 *   B.2  φ₀      = φRH · β(fcm) · β(t₀)
 *   B.3a φRH     (fcm ≤ 35 MPa)
 *   B.3b φRH     (fcm > 35 MPa)
 *   B.4  β(fcm)  = 16.8 / √fcm
 *   B.5  β(t₀)   = 1 / (0.1 + t₀^0.2)
 *   B.6  h₀      = 2Ac / u
 *   B.7  βc(t,t₀)
 *   B.8a βH      (fcm ≤ 35 MPa)
 *   B.8b βH      (fcm ≥ 35 MPa)
 *   B.8c α₁, α₂, α₃
 *   B.9  t₀ adjusted for cement class
 */

$(function () {

  /* ── bind all inputs ── */
  $('#t0, #t, #fck, #rh, #u, #ac, #cement').on('input change', calculate);

  function calculate() {

    var t0_raw = parseFloat($('#t0').val());
    var t      = parseFloat($('#t').val());
    var fck    = parseFloat($('#fck').val());
    var RH     = parseFloat($('#rh').val());
    var u      = parseFloat($('#u').val());
    var Ac     = parseFloat($('#ac').val());
    var cement = $('#cement').val();

    var $resultMain = $('#result-main');
    var $stepsGrid  = $('#steps-grid');
    var $warnMsg    = $('#warn-msg');
    var $errMsg     = $('#err-msg');

    /* reset notices */
    $warnMsg.hide().html('');
    $errMsg.hide().html('');

    /* require all numeric fields to be valid positive numbers */
    var anyMissing = [t0_raw, t, fck, RH, u, Ac].some(function (v) {
      return isNaN(v) || v <= 0;
    });

    if (anyMissing) {
      $resultMain.html('<span class="result-placeholder">Fill in all fields to see &phi;(t, t&#8320;)</span>');
      $stepsGrid.hide();
      return;
    }

    /* logical constraint: t must be > t₀ */
    if (t <= t0_raw) {
      $resultMain.html('<span class="result-placeholder">t must be greater than t&#8320;</span>');
      $stepsGrid.hide();
      $errMsg.html('The considered age <em>t</em> must be greater than the age at loading <em>t&#8320;</em>.').show();
      return;
    }

    /* ── cement class exponent (B.9) ── */
    var alphaMap = { S: -1, N: 0, R: 1 };
    var alpha    = alphaMap[cement];

    /* ── derived quantities ── */
    var f_cm = fck + 8;                                           /* mean strength          */
    var h0   = (2 * Ac) / u;                                     /* notional size  (B.6)   */

    /* adjusted age at loading (B.9) — t₀,T assumed = t₀,raw */
    var t0 = Math.max(0.5,
      t0_raw * Math.pow(9 / (2 + Math.pow(t0_raw, 1.2)) + 1, alpha)
    );

    /* β(fcm)  (B.4) */
    var beta_fcm = 16.8 / Math.sqrt(f_cm);

    /* β(t₀)   (B.5) */
    var beta_t0 = 1 / (0.1 + Math.pow(t0, 0.2));

    /* α coefficients (B.8c) — only needed when fcm > 35 */
    var alpha1 = Math.pow(35 / f_cm, 0.7);
    var alpha2 = Math.pow(35 / f_cm, 0.2);
    var alpha3 = Math.pow(35 / f_cm, 0.5);

    /* φRH  (B.3a / B.3b) */
    var phi_RH, eq_RH;
    if (f_cm <= 35) {
      phi_RH = 1 + (1 - RH / 100) / (0.1 * Math.cbrt(h0));
      eq_RH  = 'B.3a';
    } else {
      phi_RH = (1 + (1 - RH / 100) / (0.1 * Math.cbrt(h0)) * alpha1) * alpha2;
      eq_RH  = 'B.3b';
    }

    /* φ₀  (B.2) */
    var phi0 = phi_RH * beta_fcm * beta_t0;

    /* βH  (B.8a / B.8b) */
    var beta_H, eq_H;
    if (f_cm <= 35) {
      beta_H = Math.min(1500,
        1.5 * (1 + Math.pow(0.012 * RH, 18)) * h0 + 250
      );
      eq_H = 'B.8a';
    } else {
      beta_H = Math.min(1500 * alpha3,
        1.5 * (1 + Math.pow(0.012 * RH, 18)) * h0 + 250 * alpha3
      );
      eq_H = 'B.8b';
    }

    /* βc(t,t₀)  (B.7) */
    var beta_c = Math.pow((t - t0_raw) / (beta_H + t - t0_raw), 0.3);

    /* φ(t,t₀)  (B.1) */
    var phi = phi0 * beta_c;

    /* ── display result ── */
    $resultMain.html(
      '<span class="result-label">&phi;(t, t&#8320;) =</span>' +
      '<span class="result-value">' + phi.toFixed(3) + '</span>'
    );

    /* ── intermediate steps ── */
    var steps = [
      { label: 'f<sub>cm</sub>',         value: f_cm.toFixed(1)    + ' N/mm&sup2;', ref: '= f<sub>ck</sub> + 8'         },
      { label: 'h&#8320;',               value: h0.toFixed(1)      + ' mm',         ref: 'B.6'                           },
      { label: 't&#8320; adjusted',       value: t0.toFixed(2)      + ' days',       ref: 'B.9, class ' + cement         },
      { label: '&phi;<sub>RH</sub>',      value: phi_RH.toFixed(4),                  ref: eq_RH                           },
      { label: '&beta;(f<sub>cm</sub>)',  value: beta_fcm.toFixed(4),                ref: 'B.4'                           },
      { label: '&beta;(t&#8320;)',        value: beta_t0.toFixed(4),                 ref: 'B.5'                           },
      { label: '&phi;&#8320;',            value: phi0.toFixed(4),                    ref: 'B.2'                           },
      { label: '&beta;<sub>H</sub>',      value: beta_H.toFixed(2),                  ref: eq_H                            },
      { label: '&beta;<sub>c</sub>(t,t&#8320;)', value: beta_c.toFixed(4),           ref: 'B.7'                           }
    ];

    var html = '';
    $.each(steps, function (_, s) {
      html +=
        '<div class="step-card">' +
          '<div class="sc-label">'  + s.label + '</div>' +
          '<div class="sc-value">'  + s.value + '</div>' +
          '<div class="sc-ref">'    + s.ref   + '</div>' +
        '</div>';
    });
    $stepsGrid.html(html).show();

    /* ── range warnings ── */
    var warnings = [];
    if (fck < 12 || fck > 90) {
      warnings.push('f<sub>ck</sub> is outside the typical Eurocode range (12 – 90 N/mm&sup2;).');
    }
    if (RH < 40 || RH > 100) {
      warnings.push('RH is outside the recommended range (40 – 100 %).');
    }
    if (warnings.length) {
      $warnMsg.html('&#9888; ' + warnings.join(' ')).show();
    }
  }

});
</script>
]]></content:encoded>
					
		
		
			</item>
	</channel>
</rss>
